Re: [Tutor] sorting data from multiple arrays
Jeff Peery wrote:
> ... what is '*' in '*temp'? thanks!
Say you have a function of 3 arguments:
In [1]: def add(a, b, c):
...: return a+b+c
Normally to call it, you just specify the three arguments:
In [2]: add(1, 2, 3)
Out[2]: 6
Suppose the arguments were already in a list, what would you do? You
can't just pass the list, that is a single argument and you need three:
In [3]: data=[1, 2, 3]
In [4]: add(data)
Traceback (most recent call last):
File "", line 1, in
: add() takes exactly 3 arguments (1 given)
You could unpack the data yourself:
In [5]: a, b, c = data
In [6]: add(a, b, c)
Out[6]: 6
Or you can use the * notation, which basically means, "treat each
element of this list as a separate argument", or "use this list as the
argument list directly":
In [7]: add(*data)
Out[7]: 6
If the length of the argument list (data, in the example above) can
change, manually unpacking the list won't work and the * syntax is the
only alternative.
Kent
> Decorate-sort-undecorate
> (http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/52234)
> to the rescue:
>
> In [12]: a = [3,2,1,4]
> In [13]: b = ['hi', 'my','name', 'is']
> In [14]: c = [5,2,4,2]
> In [15]: temp = zip(a, b, c)
> In [16]: temp
> Out[16]: [(3, 'hi', 5), (2, 'my', 2), (1, 'name', 4), (4, 'is', 2)]
> In [17]: temp.sort()
> In [18]: _, b, c = zip(*temp)
> In [19]: b
> Out[19]: ('name', 'my', 'hi', 'is')
> In [20]: c
> Out[20]: (4, 2, 5, 2)
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Re: [Tutor] sorting data from multiple arrays
... what is '*' in '*temp'? thanks!
J
Kent Johnson <[EMAIL PROTECTED]> wrote: Jeff Peery wrote:
> hello, I typically run into this problem and I'm not always sure of the
> most efficient way to handle it. I often work with multiple arrays of
> data, say arrays a, b, and c, and I want to sort the elements of b and c
> based on a. for example:
>
> a = [3,2,1,4]
> b = ['hi', 'my','name', 'is']
> c = [5,2,4,2]
>
> I order 'a' from small to large and do the same rearrangement to 'b' and
> 'c':
> a = [1,2,3,4]
> b = ['name', 'my','hi', 'is']
> c = [4,2,5,2]
>
> usually I do some terrible looking for loops and iterate over the whole
> mess is there a clean, efficient way to do this, or is there a nice
> function that would reorder the elements of b and c based on the soring
> of a?
Decorate-sort-undecorate
(http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/52234)
to the rescue:
In [12]: a = [3,2,1,4]
In [13]: b = ['hi', 'my','name', 'is']
In [14]: c = [5,2,4,2]
In [15]: temp = zip(a, b, c)
In [16]: temp
Out[16]: [(3, 'hi', 5), (2, 'my', 2), (1, 'name', 4), (4, 'is', 2)]
In [17]: temp.sort()
In [18]: _, b, c = zip(*temp)
In [19]: b
Out[19]: ('name', 'my', 'hi', 'is')
In [20]: c
Out[20]: (4, 2, 5, 2)
Or, if you are a fan of one-liners:
In [21]: _, b, c = zip(*sorted(zip(a, b, c)))
Methinks there should be a clever way to do this with the key= argument
to sort, but I can't think of it at the moment...
Kent
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Re: [Tutor] sorting data from multiple arrays
Thanks for all the responses, that is a huge help!
Jeff
Kent Johnson <[EMAIL PROTECTED]> wrote: Jeff Peery wrote:
> hello, I typically run into this problem and I'm not always sure of the
> most efficient way to handle it. I often work with multiple arrays of
> data, say arrays a, b, and c, and I want to sort the elements of b and c
> based on a. for example:
>
> a = [3,2,1,4]
> b = ['hi', 'my','name', 'is']
> c = [5,2,4,2]
>
> I order 'a' from small to large and do the same rearrangement to 'b' and
> 'c':
> a = [1,2,3,4]
> b = ['name', 'my','hi', 'is']
> c = [4,2,5,2]
>
> usually I do some terrible looking for loops and iterate over the whole
> mess is there a clean, efficient way to do this, or is there a nice
> function that would reorder the elements of b and c based on the soring
> of a?
Decorate-sort-undecorate
(http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/52234)
to the rescue:
In [12]: a = [3,2,1,4]
In [13]: b = ['hi', 'my','name', 'is']
In [14]: c = [5,2,4,2]
In [15]: temp = zip(a, b, c)
In [16]: temp
Out[16]: [(3, 'hi', 5), (2, 'my', 2), (1, 'name', 4), (4, 'is', 2)]
In [17]: temp.sort()
In [18]: _, b, c = zip(*temp)
In [19]: b
Out[19]: ('name', 'my', 'hi', 'is')
In [20]: c
Out[20]: (4, 2, 5, 2)
Or, if you are a fan of one-liners:
In [21]: _, b, c = zip(*sorted(zip(a, b, c)))
Methinks there should be a clever way to do this with the key= argument
to sort, but I can't think of it at the moment...
Kent
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Re: [Tutor] sorting data from multiple arrays
Jeff Peery wrote:
> hello, I typically run into this problem and I'm not always sure of the
> most efficient way to handle it. I often work with multiple arrays of
> data, say arrays a, b, and c, and I want to sort the elements of b and c
> based on a. for example:
>
> a = [3,2,1,4]
> b = ['hi', 'my','name', 'is']
> c = [5,2,4,2]
>
> I order 'a' from small to large and do the same rearrangement to 'b' and
> 'c':
> a = [1,2,3,4]
> b = ['name', 'my','hi', 'is']
> c = [4,2,5,2]
>
> usually I do some terrible looking for loops and iterate over the whole
> mess is there a clean, efficient way to do this, or is there a nice
> function that would reorder the elements of b and c based on the soring
> of a?
Decorate-sort-undecorate
(http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/52234)
to the rescue:
In [12]: a = [3,2,1,4]
In [13]: b = ['hi', 'my','name', 'is']
In [14]: c = [5,2,4,2]
In [15]: temp = zip(a, b, c)
In [16]: temp
Out[16]: [(3, 'hi', 5), (2, 'my', 2), (1, 'name', 4), (4, 'is', 2)]
In [17]: temp.sort()
In [18]: _, b, c = zip(*temp)
In [19]: b
Out[19]: ('name', 'my', 'hi', 'is')
In [20]: c
Out[20]: (4, 2, 5, 2)
Or, if you are a fan of one-liners:
In [21]: _, b, c = zip(*sorted(zip(a, b, c)))
Methinks there should be a clever way to do this with the key= argument
to sort, but I can't think of it at the moment...
Kent
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Re: [Tutor] sorting data from multiple arrays
> hello, I typically run into this problem and I'm not always sure of the most
> efficient way to handle it. I often work with multiple arrays of data, say
> arrays a, b, and c, and I want to sort the
> elements of b and c based on a. for example:
> a = [3,2,1,4]
> b = ['hi', 'my','name', 'is']
> c = [5,2,4,2]
> I order 'a' from small to large and do the same rearrangement to 'b' and 'c':
> a = [1,2,3,4]
> b = ['name', 'my','hi', 'is']
> c = [4,2,5,2]
> usually I do some terrible looking for loops and iterate over the whole
> mess is there a clean, efficient way to do this, or is there a nice
> function that would reorder the elements of b and c
> based on the soring of a?
Is switching to a dictionary an option?
mystuff = {3: ('hi', 5),
2: ('my', 2),
1: ('name', 4),
4: ('is', 2)}
You can get a list of the keys, sort _that_, then fetch from the dict
based on the sorted list.
Alan
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