Re: [Numpy-discussion] Silent Broadcasting considered harmful
Yeah Im aware of that, thats the reason why I suggested a warning level as an alternative. Setting no warnings as default would avoid breaking existing code. Gesendet:Sonntag, 08. Februar 2015 um 22:08 Uhr Von:Eelco Hoogendoorn hoogendoorn.ee...@gmail.com An:Discussion of Numerical Python numpy-discussion@scipy.org Betreff:Re: [Numpy-discussion] Silent Broadcasting considered harmful I personally use Octave and/or Numpy for several years now and never ever needed braodcasting. But since it is still there there will be many users who need it, there will be some use for it. Uhm, yeah, there is some use for it. Im all for explicit over implicit, but personally current broadcasting rules have never bothered me, certainly not to the extent of justifying massive backwards compatibility violations. Take It from someone who relies on broadcasting for every other line of code. ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Silent Broadcasting considered harmful
On Sun, Feb 8, 2015 at 4:08 PM, Eelco Hoogendoorn hoogendoorn.ee...@gmail.com wrote: I personally use Octave and/or Numpy for several years now and never ever needed braodcasting. But since it is still there there will be many users who need it, there will be some use for it. Uhm, yeah, there is some use for it. Im all for explicit over implicit, but personally current broadcasting rules have never bothered me, certainly not to the extent of justifying massive backwards compatibility violations. Take It from someone who relies on broadcasting for every other line of code. On Sun, Feb 8, 2015 at 10:03 PM, Stefan Reiterer dom...@gmx.net wrote: Hi! As shortly discussed on github: https://github.com/numpy/numpy/issues/5541 I personally think that silent Broadcasting is not a good thing. I had recently a lot of trouble with row and column vectors which got bradcastet toghether altough it was more annoying than useful, especially since I had to search deep down into the code to find out that the problem was nothing else than Broadcasting... I personally use Octave and/or Numpy for several years now and never ever needed braodcasting. But since it is still there there will be many users who need it, there will be some use for it. So I suggest that the best would be to throw warnings when arrays get Broadcasted like Octave do. Python warnings can be catched and handled, that would be a great benefit. Another idea would to provide warning levels for braodcasting, e.g 0 = Never, 1=Warn once, 2=Warn always, 3 = Forbid aka throw exception, with 0 as default. This would avoid breaking other code, and give the user some control over braodcasting. Kind regards, Stefan Numpy broadcasting is the greatest feature of numpy !!! It just takes a bit of getting used to coming from another matrix language. Josef what 3!? ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Silent Broadcasting considered harmful
On Sun, Feb 8, 2015 at 2:14 PM, Stefan Reiterer dom...@gmx.net wrote: Yeah I'm aware of that, that's the reason why I suggested a warning level as an alternative. Setting no warnings as default would avoid breaking existing code. *Gesendet:* Sonntag, 08. Februar 2015 um 22:08 Uhr *Von:* Eelco Hoogendoorn hoogendoorn.ee...@gmail.com *An:* Discussion of Numerical Python numpy-discussion@scipy.org *Betreff:* Re: [Numpy-discussion] Silent Broadcasting considered harmful I personally use Octave and/or Numpy for several years now and never ever needed braodcasting. But since it is still there there will be many users who need it, there will be some use for it. Uhm, yeah, there is some use for it. Im all for explicit over implicit, but personally current broadcasting rules have never bothered me, certainly not to the extent of justifying massive backwards compatibility violations. Take It from someone who relies on broadcasting for every other line of code. It's how numpy works. It would be like getting into your car and being warned that it has wheels. Chuck ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Silent Broadcasting considered harmful
I dont think this is a good comparison, especially since broadcasting is a feature not a necessity... Its more like turning off/on driving assistance. And as already mentioned: other matrix languages also allow it, but they warn about its usage. This has indeed its merits. Gesendet:Sonntag, 08. Februar 2015 um 22:17 Uhr Von:Charles R Harris charlesr.har...@gmail.com An:Discussion of Numerical Python numpy-discussion@scipy.org Betreff:Re: [Numpy-discussion] Silent Broadcasting considered harmful On Sun, Feb 8, 2015 at 2:14 PM, Stefan Reiterer dom...@gmx.net wrote: Yeah Im aware of that, thats the reason why I suggested a warning level as an alternative. Setting no warnings as default would avoid breaking existing code. Gesendet:Sonntag, 08. Februar 2015 um 22:08 Uhr Von:Eelco Hoogendoorn hoogendoorn.ee...@gmail.com An:Discussion of Numerical Python numpy-discussion@scipy.org Betreff:Re: [Numpy-discussion] Silent Broadcasting considered harmful I personally use Octave and/or Numpy for several years now and never ever needed braodcasting. But since it is still there there will be many users who need it, there will be some use for it. Uhm, yeah, there is some use for it. Im all for explicit over implicit, but personally current broadcasting rules have never bothered me, certainly not to the extent of justifying massive backwards compatibility violations. Take It from someone who relies on broadcasting for every other line of code. Its how numpy works. It would be like getting into your car and being warned that it has wheels. Chuck ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Silent Broadcasting considered harmful
Hi, On Sun, Feb 8, 2015 at 1:24 PM, Stefan Reiterer dom...@gmx.net wrote: I don't think this is a good comparison, especially since broadcasting is a feature not a necessity ... It's more like turning off/on driving assistance. And as already mentioned: other matrix languages also allow it, but they warn about it's usage. This has indeed it's merits. Gesendet: Sonntag, 08. Februar 2015 um 22:17 Uhr Von: Charles R Harris charlesr.har...@gmail.com An: Discussion of Numerical Python numpy-discussion@scipy.org Betreff: Re: [Numpy-discussion] Silent Broadcasting considered harmful On Sun, Feb 8, 2015 at 2:14 PM, Stefan Reiterer dom...@gmx.net wrote: Yeah I'm aware of that, that's the reason why I suggested a warning level as an alternative. Setting no warnings as default would avoid breaking existing code. Gesendet: Sonntag, 08. Februar 2015 um 22:08 Uhr Von: Eelco Hoogendoorn hoogendoorn.ee...@gmail.com An: Discussion of Numerical Python numpy-discussion@scipy.org Betreff: Re: [Numpy-discussion] Silent Broadcasting considered harmful I personally use Octave and/or Numpy for several years now and never ever needed braodcasting. But since it is still there there will be many users who need it, there will be some use for it. Uhm, yeah, there is some use for it. Im all for explicit over implicit, but personally current broadcasting rules have never bothered me, certainly not to the extent of justifying massive backwards compatibility violations. Take It from someone who relies on broadcasting for every other line of code. It's how numpy works. It would be like getting into your car and being warned that it has wheels. I agree. I knew about broadcasting as soon as I started using numpy, so I can honestly say this has never surprised me. There are other major incompatibilities between Matlab and numpy, such as 0-based indices, and array views. I think the matrix class would solve this for you, although most of us don't use that very much. It would be a major change to warn about broadcasting by default, and it would be odd, because we encourage broadcasting in our docs and common code, rightly I think. The naive user would not know to turn on this warning. I could imagine a non-default warning, but I doubt it would be much used. Cheers, Matthew ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Silent Broadcasting considered harmful
On Sun, Feb 8, 2015 at 4:24 PM, Stefan Reiterer dom...@gmx.net wrote: I don't think this is a good comparison, especially since broadcasting is a feature not a necessity ... It's more like turning off/on driving assistance. And as already mentioned: other matrix languages also allow it, but they warn about it's usage. This has indeed it's merits. *Gesendet:* Sonntag, 08. Februar 2015 um 22:17 Uhr *Von:* Charles R Harris charlesr.har...@gmail.com *An:* Discussion of Numerical Python numpy-discussion@scipy.org *Betreff:* Re: [Numpy-discussion] Silent Broadcasting considered harmful On Sun, Feb 8, 2015 at 2:14 PM, Stefan Reiterer dom...@gmx.net wrote: Yeah I'm aware of that, that's the reason why I suggested a warning level as an alternative. Setting no warnings as default would avoid breaking existing code. *Gesendet:* Sonntag, 08. Februar 2015 um 22:08 Uhr *Von:* Eelco Hoogendoorn hoogendoorn.ee...@gmail.com *An:* Discussion of Numerical Python numpy-discussion@scipy.org *Betreff:* Re: [Numpy-discussion] Silent Broadcasting considered harmful I personally use Octave and/or Numpy for several years now and never ever needed braodcasting. But since it is still there there will be many users who need it, there will be some use for it. Uhm, yeah, there is some use for it. Im all for explicit over implicit, but personally current broadcasting rules have never bothered me, certainly not to the extent of justifying massive backwards compatibility violations. Take It from someone who relies on broadcasting for every other line of code. It's how numpy works. It would be like getting into your car and being warned that it has wheels. Chuck ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion I agree, I do not think this is a good comparison. All cars have wheels, there are no surprises there. This is more like a car that decides to do something completely different from everything that you learned about in driving school. I find the broadcasting aspect of Numpy a turn off. If I go to add a 1x3 vector to a 3x1 vector, I want the program to warn me or error out. I don't want it to do something under the covers that has no mathematical basis or definition. Also, Octave may provide a warning, but Matlab errors out...Matrix dimensions must agree. Which they must, at least in my world. ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Silent Broadcasting considered harmful
On Sun, 8 Feb 2015, Stefan Reiterer wrote: And as already mentioned: other matrix languages also allow it, but they warn about it's usage. This has indeed it's merits. numpy isn't a matrix language. They're arrays. Storing numbers that you are thinking of as a vector in an array doesn't turn the array into a vector. There are linear algebra modules; I haven't used them. w ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Silent Broadcasting considered harmful
Hi, On Sun, Feb 8, 2015 at 1:39 PM, Simon Wood sgwoo...@gmail.com wrote: On Sun, Feb 8, 2015 at 4:24 PM, Stefan Reiterer dom...@gmx.net wrote: I don't think this is a good comparison, especially since broadcasting is a feature not a necessity ... It's more like turning off/on driving assistance. And as already mentioned: other matrix languages also allow it, but they warn about it's usage. This has indeed it's merits. Gesendet: Sonntag, 08. Februar 2015 um 22:17 Uhr Von: Charles R Harris charlesr.har...@gmail.com An: Discussion of Numerical Python numpy-discussion@scipy.org Betreff: Re: [Numpy-discussion] Silent Broadcasting considered harmful On Sun, Feb 8, 2015 at 2:14 PM, Stefan Reiterer dom...@gmx.net wrote: Yeah I'm aware of that, that's the reason why I suggested a warning level as an alternative. Setting no warnings as default would avoid breaking existing code. Gesendet: Sonntag, 08. Februar 2015 um 22:08 Uhr Von: Eelco Hoogendoorn hoogendoorn.ee...@gmail.com An: Discussion of Numerical Python numpy-discussion@scipy.org Betreff: Re: [Numpy-discussion] Silent Broadcasting considered harmful I personally use Octave and/or Numpy for several years now and never ever needed braodcasting. But since it is still there there will be many users who need it, there will be some use for it. Uhm, yeah, there is some use for it. Im all for explicit over implicit, but personally current broadcasting rules have never bothered me, certainly not to the extent of justifying massive backwards compatibility violations. Take It from someone who relies on broadcasting for every other line of code. It's how numpy works. It would be like getting into your car and being warned that it has wheels. Chuck ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion I agree, I do not think this is a good comparison. All cars have wheels, there are no surprises there. This is more like a car that decides to do something completely different from everything that you learned about in driving school. I find the broadcasting aspect of Numpy a turn off. If I go to add a 1x3 vector to a 3x1 vector, I want the program to warn me or error out. I don't want it to do something under the covers that has no mathematical basis or definition. Also, Octave may provide a warning, but Matlab errors out...Matrix dimensions must agree. Which they must, at least in my world. In a previous life, many of us were very serious users of Matlab, myself included. Matlab / Octave have a model of the array as being a matrix, but numpy does not have this model. There is a Matrix class that implements this model, but usually experienced numpy users either never use this, or stop using it. I can only say - subjectively I know - that I did not personally suffer from this when I switched to numpy from Matlab, partly because I was fully aware that I was going to have to change the way I thought about arrays, for various reasons. After a short while getting used to it, broadcasting seemed like a huge win. I guess the fact that other languages have adopted it means that others have had the same experience. So, numpy is not a straight replacement of Matlab, in terms of design. To pursue the analogy, you have learned to drive an automatic car. Numpy is a stick-shift car. There are good reasons to prefer a stick-shift, but it does mean that someone trained on an automatic is bound to feel that a stick-shift is uncomfortable for a while. Best, Matthew ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
[Numpy-discussion] Silent Broadcasting considered harmful
Hi! As shortly discussed on github: https://github.com/numpy/numpy/issues/5541 I personally think that silent Broadcasting is not a good thing. I had recently a lot of trouble with row and column vectors which got bradcastet toghether altough it was more annoying than useful, especially since I had to search deep down into the code to find out that the problem was nothing else than Broadcasting... I personally use Octave and/or Numpy for several years now and never ever needed braodcasting. But since it is still there there will be many users who need it, there will be some use for it. So I suggest that the best would be to throw warnings when arrays get Broadcasted like Octave do. Python warnings can be catched and handled, that would be a great benefit. Another idea would to provide warning levels for braodcasting, e.g 0 = Never, 1=Warn once, 2=Warn always, 3 = Forbid aka throw exception, with 0 as default. This would avoid breaking other code, and give the user some control over braodcasting. Kind regards, Stefan ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Silent Broadcasting considered harmful
I personally use Octave and/or Numpy for several years now and never ever needed braodcasting. But since it is still there there will be many users who need it, there will be some use for it. Uhm, yeah, there is some use for it. Im all for explicit over implicit, but personally current broadcasting rules have never bothered me, certainly not to the extent of justifying massive backwards compatibility violations. Take It from someone who relies on broadcasting for every other line of code. On Sun, Feb 8, 2015 at 10:03 PM, Stefan Reiterer dom...@gmx.net wrote: Hi! As shortly discussed on github: https://github.com/numpy/numpy/issues/5541 I personally think that silent Broadcasting is not a good thing. I had recently a lot of trouble with row and column vectors which got bradcastet toghether altough it was more annoying than useful, especially since I had to search deep down into the code to find out that the problem was nothing else than Broadcasting... I personally use Octave and/or Numpy for several years now and never ever needed braodcasting. But since it is still there there will be many users who need it, there will be some use for it. So I suggest that the best would be to throw warnings when arrays get Broadcasted like Octave do. Python warnings can be catched and handled, that would be a great benefit. Another idea would to provide warning levels for braodcasting, e.g 0 = Never, 1=Warn once, 2=Warn always, 3 = Forbid aka throw exception, with 0 as default. This would avoid breaking other code, and give the user some control over braodcasting. Kind regards, Stefan ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Silent Broadcasting considered harmful
Actually I use numpy for several years now, and I love it. The reason that I think silent broadcasting of sums is bad comes simply from the fact, that I had moretrouble with it, than it helped me. I wont stop using numpy because of that, but I think this behavior may backfire, and thats the reason I started this discussion. Till now the only way out of the misery is to make proper unit tests, and to be careful as hell with dimensions and shape checks. Providing optional warnings just would be an elegant way out of this. Cheers, Stefan Gesendet:Sonntag, 08. Februar 2015 um 22:56 Uhr Von:Matthew Brett matthew.br...@gmail.com An:Discussion of Numerical Python numpy-discussion@scipy.org Betreff:Re: [Numpy-discussion] Silent Broadcasting considered harmful Hi, On Sun, Feb 8, 2015 at 1:39 PM, Simon Wood sgwoo...@gmail.com wrote: On Sun, Feb 8, 2015 at 4:24 PM, Stefan Reiterer dom...@gmx.net wrote: I dont think this is a good comparison, especially since broadcasting is a feature not a necessity ... Its more like turning off/on driving assistance. And as already mentioned: other matrix languages also allow it, but they warn about its usage. This has indeed its merits. Gesendet: Sonntag, 08. Februar 2015 um 22:17 Uhr Von: Charles R Harris charlesr.har...@gmail.com An: Discussion of Numerical Python numpy-discussion@scipy.org Betreff: Re: [Numpy-discussion] Silent Broadcasting considered harmful On Sun, Feb 8, 2015 at 2:14 PM, Stefan Reiterer dom...@gmx.net wrote: Yeah Im aware of that, thats the reason why I suggested a warning level as an alternative. Setting no warnings as default would avoid breaking existing code. Gesendet: Sonntag, 08. Februar 2015 um 22:08 Uhr Von: Eelco Hoogendoorn hoogendoorn.ee...@gmail.com An: Discussion of Numerical Python numpy-discussion@scipy.org Betreff: Re: [Numpy-discussion] Silent Broadcasting considered harmful I personally use Octave and/or Numpy for several years now and never ever needed braodcasting. But since it is still there there will be many users who need it, there will be some use for it. Uhm, yeah, there is some use for it. Im all for explicit over implicit, but personally current broadcasting rules have never bothered me, certainly not to the extent of justifying massive backwards compatibility violations. Take It from someone who relies on broadcasting for every other line of code. Its how numpy works. It would be like getting into your car and being warned that it has wheels. Chuck ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion I agree, I do not think this is a good comparison. All cars have wheels, there are no surprises there. This is more like a car that decides to do something completely different from everything that you learned about in driving school. I find the broadcasting aspect of Numpy a turn off. If I go to add a 1x3 vector to a 3x1 vector, I want the program to warn me or error out. I dont want it to do something under the covers that has no mathematical basis or definition. Also, Octave may provide a warning, but Matlab errors out...Matrix dimensions must agree. Which they must, at least in my world. In a previous life, many of us were very serious users of Matlab, myself included. Matlab / Octave have a model of the array as being a matrix, but numpy does not have this model. There is a Matrix class that implements this model, but usually experienced numpy users either never use this, or stop using it. I can only say - subjectively I know - that I did not personally suffer from this when I switched to numpy from Matlab, partly because I was fully aware that I was going to have to change the way I thought about arrays, for various reasons. After a short while getting used to it, broadcasting seemed like a huge win. I guess the fact that other languages have adopted it means that others have had the same experience. So, numpy is not a straight replacement of Matlab, in terms of design. To pursue the analogy, you have learned to drive an automatic car. Numpy is a stick-shift car. There are good reasons to prefer a stick-shift, but it does mean that someone trained on an automatic is bound to feel that a stick-shift is uncomfortable for a while. Best, Matthew ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Silent Broadcasting considered harmful
On Sun, Feb 8, 2015 at 4:56 PM, Matthew Brett matthew.br...@gmail.com wrote: Hi, On Sun, Feb 8, 2015 at 1:39 PM, Simon Wood sgwoo...@gmail.com wrote: On Sun, Feb 8, 2015 at 4:24 PM, Stefan Reiterer dom...@gmx.net wrote: I don't think this is a good comparison, especially since broadcasting is a feature not a necessity ... It's more like turning off/on driving assistance. And as already mentioned: other matrix languages also allow it, but they warn about it's usage. This has indeed it's merits. Gesendet: Sonntag, 08. Februar 2015 um 22:17 Uhr Von: Charles R Harris charlesr.har...@gmail.com An: Discussion of Numerical Python numpy-discussion@scipy.org Betreff: Re: [Numpy-discussion] Silent Broadcasting considered harmful On Sun, Feb 8, 2015 at 2:14 PM, Stefan Reiterer dom...@gmx.net wrote: Yeah I'm aware of that, that's the reason why I suggested a warning level as an alternative. Setting no warnings as default would avoid breaking existing code. Gesendet: Sonntag, 08. Februar 2015 um 22:08 Uhr Von: Eelco Hoogendoorn hoogendoorn.ee...@gmail.com An: Discussion of Numerical Python numpy-discussion@scipy.org Betreff: Re: [Numpy-discussion] Silent Broadcasting considered harmful I personally use Octave and/or Numpy for several years now and never ever needed braodcasting. But since it is still there there will be many users who need it, there will be some use for it. Uhm, yeah, there is some use for it. Im all for explicit over implicit, but personally current broadcasting rules have never bothered me, certainly not to the extent of justifying massive backwards compatibility violations. Take It from someone who relies on broadcasting for every other line of code. It's how numpy works. It would be like getting into your car and being warned that it has wheels. Chuck ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion I agree, I do not think this is a good comparison. All cars have wheels, there are no surprises there. This is more like a car that decides to do something completely different from everything that you learned about in driving school. I find the broadcasting aspect of Numpy a turn off. If I go to add a 1x3 vector to a 3x1 vector, I want the program to warn me or error out. I don't want it to do something under the covers that has no mathematical basis or definition. Also, Octave may provide a warning, but Matlab errors out...Matrix dimensions must agree. Which they must, at least in my world. In a previous life, many of us were very serious users of Matlab, myself included. Matlab / Octave have a model of the array as being a matrix, but numpy does not have this model. There is a Matrix class that implements this model, but usually experienced numpy users either never use this, or stop using it. I can only say - subjectively I know - that I did not personally suffer from this when I switched to numpy from Matlab, partly because I was fully aware that I was going to have to change the way I thought about arrays, for various reasons. After a short while getting used to it, broadcasting seemed like a huge win. I guess the fact that other languages have adopted it means that others have had the same experience. So, numpy is not a straight replacement of Matlab, in terms of design. To pursue the analogy, you have learned to drive an automatic car. Numpy is a stick-shift car. There are good reasons to prefer a stick-shift, but it does mean that someone trained on an automatic is bound to feel that a stick-shift is uncomfortable for a while. I think the analogy is Python printing at the start and all the time a warning We use indentation, not braces, brackets or `end` to indicate blocks of code. Josef Best, Matthew ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Silent Broadcasting considered harmful
On Sun, Feb 8, 2015 at 5:17 PM, Stefan Reiterer dom...@gmx.net wrote: Actually I use numpy for several years now, and I love it. The reason that I think silent broadcasting of sums is bad comes simply from the fact, that I had more trouble with it, than it helped me. I won't stop using numpy because of that, but I think this behavior may backfire, and thats the reason I started this discussion. Till now the only way out of the misery is to make proper unit tests, and to be careful as hell with dimensions and shape checks. I fully agree with the last part. We need a lot more checks and be a lot more careful in numpy than in matlab. But that's a fundamental difference between the array versus matrix approach. For me the main behavior I had to adjust to was loosing a dimension in any reduce operation, mean, sum, ... if x is 2d x - x.mean(1) we loose a dimension, and it doesn't broadcast in the right direction x - x.mean(0) perfect, no `repeat` needed, it just broadcasts the way we need. Josef Providing optional warnings just would be an elegant way out of this. Cheers, Stefan Gesendet: Sonntag, 08. Februar 2015 um 22:56 Uhr Von: Matthew Brett matthew.br...@gmail.com An: Discussion of Numerical Python numpy-discussion@scipy.org Betreff: Re: [Numpy-discussion] Silent Broadcasting considered harmful Hi, On Sun, Feb 8, 2015 at 1:39 PM, Simon Wood sgwoo...@gmail.com wrote: On Sun, Feb 8, 2015 at 4:24 PM, Stefan Reiterer dom...@gmx.net wrote: I don't think this is a good comparison, especially since broadcasting is a feature not a necessity ... It's more like turning off/on driving assistance. And as already mentioned: other matrix languages also allow it, but they warn about it's usage. This has indeed it's merits. Gesendet: Sonntag, 08. Februar 2015 um 22:17 Uhr Von: Charles R Harris charlesr.har...@gmail.com An: Discussion of Numerical Python numpy-discussion@scipy.org Betreff: Re: [Numpy-discussion] Silent Broadcasting considered harmful On Sun, Feb 8, 2015 at 2:14 PM, Stefan Reiterer dom...@gmx.net wrote: Yeah I'm aware of that, that's the reason why I suggested a warning level as an alternative. Setting no warnings as default would avoid breaking existing code. Gesendet: Sonntag, 08. Februar 2015 um 22:08 Uhr Von: Eelco Hoogendoorn hoogendoorn.ee...@gmail.com An: Discussion of Numerical Python numpy-discussion@scipy.org Betreff: Re: [Numpy-discussion] Silent Broadcasting considered harmful I personally use Octave and/or Numpy for several years now and never ever needed braodcasting. But since it is still there there will be many users who need it, there will be some use for it. Uhm, yeah, there is some use for it. Im all for explicit over implicit, but personally current broadcasting rules have never bothered me, certainly not to the extent of justifying massive backwards compatibility violations. Take It from someone who relies on broadcasting for every other line of code. It's how numpy works. It would be like getting into your car and being warned that it has wheels. Chuck ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion I agree, I do not think this is a good comparison. All cars have wheels, there are no surprises there. This is more like a car that decides to do something completely different from everything that you learned about in driving school. I find the broadcasting aspect of Numpy a turn off. If I go to add a 1x3 vector to a 3x1 vector, I want the program to warn me or error out. I don't want it to do something under the covers that has no mathematical basis or definition. Also, Octave may provide a warning, but Matlab errors out...Matrix dimensions must agree. Which they must, at least in my world. In a previous life, many of us were very serious users of Matlab, myself included. Matlab / Octave have a model of the array as being a matrix, but numpy does not have this model. There is a Matrix class that implements this model, but usually experienced numpy users either never use this, or stop using it. I can only say - subjectively I know - that I did not personally suffer from this when I switched to numpy from Matlab, partly because I was fully aware that I was going to have to change the way I thought about arrays, for various reasons. After a short while getting used to it, broadcasting seemed like a huge win. I guess the fact that other languages have adopted it means that others have had the same experience. So, numpy is not a straight replacement of Matlab, in terms of design. To pursue the analogy, you have learned to drive an automatic car. Numpy is a stick-shift car. There are good reasons to prefer a stick-shift, but it does mean that someone trained on an automatic is bound to feel that a stick-shift is uncomfortable for a while. Best, Matthew
Re: [Numpy-discussion] Silent Broadcasting considered harmful
On 8 Feb 2015 13:39, Simon Wood sgwoo...@gmail.com wrote: I find the broadcasting aspect of Numpy a turn off. If I go to add a 1x3 vector to a 3x1 vector, I want the program to warn me or error out. I don't want it to do something under the covers that has no mathematical basis or definition. Also, Octave may provide a warning, but Matlab errors out...Matrix dimensions must agree. Which they must, at least in my world. There may be another matlab/numpy idiom clash here that's affecting this: in MATLAB, vectors are always 1 x n or n x 1, because of the matrix focused history. In numpy the idiomatic thing to do is to make vectors one-dimensional, and then this confusion cannot arise. Indeed, the only cases I'm thinking of where I even create a 3x1 or 1x3 vector in the first place are when I'm about to do something clever with broadcasting. -n ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Silent Broadcasting considered harmful
On Sun, Feb 8, 2015 at 5:28 PM, josef.p...@gmail.com wrote: On Sun, Feb 8, 2015 at 4:56 PM, Matthew Brett matthew.br...@gmail.com wrote: Hi, On Sun, Feb 8, 2015 at 1:39 PM, Simon Wood sgwoo...@gmail.com wrote: On Sun, Feb 8, 2015 at 4:24 PM, Stefan Reiterer dom...@gmx.net wrote: I don't think this is a good comparison, especially since broadcasting is a feature not a necessity ... It's more like turning off/on driving assistance. And as already mentioned: other matrix languages also allow it, but they warn about it's usage. This has indeed it's merits. Gesendet: Sonntag, 08. Februar 2015 um 22:17 Uhr Von: Charles R Harris charlesr.har...@gmail.com An: Discussion of Numerical Python numpy-discussion@scipy.org Betreff: Re: [Numpy-discussion] Silent Broadcasting considered harmful On Sun, Feb 8, 2015 at 2:14 PM, Stefan Reiterer dom...@gmx.net wrote: Yeah I'm aware of that, that's the reason why I suggested a warning level as an alternative. Setting no warnings as default would avoid breaking existing code. Gesendet: Sonntag, 08. Februar 2015 um 22:08 Uhr Von: Eelco Hoogendoorn hoogendoorn.ee...@gmail.com An: Discussion of Numerical Python numpy-discussion@scipy.org Betreff: Re: [Numpy-discussion] Silent Broadcasting considered harmful I personally use Octave and/or Numpy for several years now and never ever needed braodcasting. But since it is still there there will be many users who need it, there will be some use for it. Uhm, yeah, there is some use for it. Im all for explicit over implicit, but personally current broadcasting rules have never bothered me, certainly not to the extent of justifying massive backwards compatibility violations. Take It from someone who relies on broadcasting for every other line of code. It's how numpy works. It would be like getting into your car and being warned that it has wheels. Chuck ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion I agree, I do not think this is a good comparison. All cars have wheels, there are no surprises there. This is more like a car that decides to do something completely different from everything that you learned about in driving school. I find the broadcasting aspect of Numpy a turn off. If I go to add a 1x3 vector to a 3x1 vector, I want the program to warn me or error out. I don't want it to do something under the covers that has no mathematical basis or definition. Also, Octave may provide a warning, but Matlab errors out...Matrix dimensions must agree. Which they must, at least in my world. In a previous life, many of us were very serious users of Matlab, myself included. Matlab / Octave have a model of the array as being a matrix, but numpy does not have this model. There is a Matrix class that implements this model, but usually experienced numpy users either never use this, or stop using it. I can only say - subjectively I know - that I did not personally suffer from this when I switched to numpy from Matlab, partly because I was fully aware that I was going to have to change the way I thought about arrays, for various reasons. After a short while getting used to it, broadcasting seemed like a huge win. I guess the fact that other languages have adopted it means that others have had the same experience. So, numpy is not a straight replacement of Matlab, in terms of design. To pursue the analogy, you have learned to drive an automatic car. Numpy is a stick-shift car. There are good reasons to prefer a stick-shift, but it does mean that someone trained on an automatic is bound to feel that a stick-shift is uncomfortable for a while. I think the analogy is Python printing at the start and all the time a warning We use indentation, not braces, brackets or `end` to indicate blocks of code. Josef Not quite the same. This is not so much about language semantics as mathematical definitions. You (the Numpy community) have decided to overload certain mathematical operators to act in a way that is not consistent with linear algebra teachings. This can be a bit confusing for people who develop and implement mathematical algorithms that have a strong foundation in linear algebra, irrespective of the language they are migrating from. With that said, I do appreciate the comments by Matthew, Eelco and others. Numpy is *not* a linear algebra package, so it does not adhere to the same mathematical definitions. This realization has cleared some things up. -Simon Best, Matthew ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion ___ NumPy-Discussion mailing list
Re: [Numpy-discussion] Silent Broadcasting considered harmful
Simon Wood sgwoo...@gmail.com wrote: Not quite the same. This is not so much about language semantics as mathematical definitions. You (the Numpy community) have decided to overload certain mathematical operators to act in a way that is not consistent with linear algebra teachings. We have overloaded the operators to make them work like Fortran 90. That is about as hardcore numerical computing semantics as you get. This can be a bit confusing for people who develop and implement mathematical algorithms that have a strong foundation in linear algebra, irrespective of the language they are migrating from. Those who develop such algorithms are probably going to use BLAS and LAPACK. Then by deduction they know about Fortran, and then by deduction they know about array broadcasting. Sturla ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Silent Broadcasting considered harmful
On 08/02/15 23:17, Stefan Reiterer wrote: Actually I use numpy for several years now, and I love it. The reason that I think silent broadcasting of sums is bad comes simply from the fact, that I had more trouble with it, than it helped me. In Fortran 90, broadcasting allows us to write concise expressions which are compiled into very efficient machine code. This would be very difficult for the compiler if the code used explicit repeats and reshapes instead of broadcasting. In NumPy and Matlab, this aspect is not equally important. But broadcasting makes array expressions more terse, and is save some redundant array copies. NumPy code tends to be memory bound; broadcasting can therefore improve performance, particularly when arrays are large. But the effect is not as dramatic as it is in Fortran. Readability is also important. Vectorized Matlab code quickly degenerates into a mess of reshapes and repmats, and can be very hard to read. NumPy and Fortran 90 codes do not loose the readability like this even in the most complicated array expressions. Sturla ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Silent Broadcasting considered harmful
Ok that are indeed some good reasons to keep the status quo, especially since performance is crucial for numpy. Its a dillemma: Using the matrix class for linear algebra would be the correct way for such thing, but the matrix API is not that powerful and beautiful as the one of arrays. On the other hand arrays are beautiful, but not exactly intended to use for linear algebra. So maybe the better way would be not to add warnings to braodcasting operations, but to overhaul the matrix class to make it more attractive for numerical linear algebra(?) Cheers, Stefan Gesendet:Sonntag, 08. Februar 2015 um 23:52 Uhr Von:Nathaniel Smith n...@pobox.com An:Discussion of Numerical Python numpy-discussion@scipy.org Betreff:Re: [Numpy-discussion] Silent Broadcasting considered harmful On 8 Feb 2015 13:04, Stefan Reiterer dom...@gmx.net wrote: So I suggest that the best would be to throw warnings when arrays get Broadcasted like Octave do. Python warnings can be catched and handled, that would be a great benefit. Another idea would to provide warning levels for braodcasting, e.g 0 = Never, 1=Warn once, 2=Warn always, 3 = Forbid aka throw exception, with 0 as default. This would avoid breaking other code, and give the user some control over braodcasting. Unfortunately adding warnings is a non-starter for technical reasons, even before we get into the more subjective debate about ideal API design: issuing a warning is extremely slow (relative to typical array operations), EVEN IF the warning is disabled. (By the time you can figure out its disabled, its too late.) So this would cause massive slowdowns in existing code. Note also that in numpy, even simple expressions like 2 * arr rely on broadcasting. Do you really want warnings for all these cases? -n ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Silent Broadcasting considered harmful
On 2015/02/08 12:43 PM, josef.p...@gmail.com wrote: For me the main behavior I had to adjust to was loosing a dimension in any reduce operation, mean, sum, ... if x is 2d x - x.mean(1) we loose a dimension, and it doesn't broadcast in the right direction Though you can use: x_demeaned = x - np.mean(x, axis=1, keepdims=True) x - x.mean(0) perfect, no `repeat` needed, it just broadcasts the way we need. Josef ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
