[Tutor] Range of float value
Hi all, I have a value that ranges between 48.01 and 48.57. a Float value in other words. I want to look at changes in the value. If my normal range is between 48.35 and 48.45, how will I identify the value below 48.35 and above 48.45? Something I tried was: for a in range(48.35, 48.45): print a It gives me a value of 100. Is it possible to get a range of a float value? Thanks Johan -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.17.30/674 - Release Date: 2007/02/07 03:33 PM ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Range of float value
Kent Johnson wrote: Johan Geldenhuys wrote: Hi all, I have a value that ranges between 48.01 and 48.57. a Float value in other words. I want to look at changes in the value. If my normal range is between 48.35 and 48.45, how will I identify the value below 48.35 and above 48.45? Something I tried was: for a in range(48.35, 48.45): print a It gives me a value of 100. Is it possible to get a range of a float value? You can't generate all the float values in a range. (OK, you probably could, but it would not be practical or useful.) You can test for a value in a range, e.g. if 48.35 = a = 48.45: Kent: Why does this work? In C++ this would go from if (48.35 = a = 48.45) to (assuming the right condition is met) if (48.35 = true) because it evaluates these things right to left, doesn't it? does python treat chained comparisons differently than C++ or is C++ behaving differently than I think it does? Thanks for your help, -Luke ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Range of float value
Luke Paireepinart wrote: Kent Johnson wrote: You can't generate all the float values in a range. (OK, you probably could, but it would not be practical or useful.) You can test for a value in a range, e.g. if 48.35 = a = 48.45: Kent: Why does this work? It is explicitly supported in Python. See file:///C:/Python25/Doc/ref/comparisons.html which says, Comparisons can be chained arbitrarily, e.g., x y = z is equivalent to x y and y = z, except that y is evaluated only once (but in both cases z is not evaluated at all when x y is found to be false). Kent In C++ this would go from if (48.35 = a = 48.45) to (assuming the right condition is met) if (48.35 = true) because it evaluates these things right to left, doesn't it? does python treat chained comparisons differently than C++ or is C++ behaving differently than I think it does? Thanks for your help, -Luke ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Range of float value
2007/2/8, Johan Geldenhuys [EMAIL PROTECTED]: Hi all, I have a value that ranges between 48.01 and 48.57. a Float value in other words. I want to look at changes in the value. If my normal range is between 48.35 and 48.45, how will I identify the value below 48.35 and above 48.45 ? Something I tried was: for a in range(48.35, 48.45): print a It gives me a value of 100. Is it possible to get a range of a float value? It depends. What would you like it to be? All numbers in that range? They're uncountably infinite, so no way we could ever get that out of the computer. All actual float values? Depends too much on the implementation of the specific machine you're working on to be workable. Identifying values below 48.35 and above 48.45 is simply done by: if value 48.35 or value 48.45 then... No need to first create the range of values -- Andre Engels, [EMAIL PROTECTED] ICQ: 6260644 -- Skype: a_engels ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Range of float value
Kent Johnson wrote: Luke Paireepinart wrote: Kent Johnson wrote: You can't generate all the float values in a range. (OK, you probably could, but it would not be practical or useful.) You can test for a value in a range, e.g. if 48.35 = a = 48.45: Kent: Why does this work? It is explicitly supported in Python. See file:///C:/Python25/Doc/ref/comparisons.html Do you mean http://docs.python.org/ref/comparisons.html ? :) ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Range of float value
Luke Paireepinart wrote: Kent Johnson wrote: Luke Paireepinart wrote: Kent Johnson wrote: You can't generate all the float values in a range. (OK, you probably could, but it would not be practical or useful.) You can test for a value in a range, e.g. if 48.35 = a = 48.45: Kent: Why does this work? It is explicitly supported in Python. See file:///C:/Python25/Doc/ref/comparisons.html Do you mean http://docs.python.org/ref/comparisons.html ? Jeez. I try so hard to bust out of here and every turn I take just brings me back to file://. Now where did I put that internet, anyway? Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Range of float value
OK, this what I wanted: I have a value: a = 48.41 My lowValue is: lowValue = 48.35 My highValue is : highvalue = 48.45 if a = lowValue: print 'value below limit' if a = highValue: print value above limit' I though that it could be possible to have a range between 48.35 and 48.45 that could have a step of 0.1 This works fine with normal intgers: def lookAtRange(a): ... if a in range(40, 110, 10):#Would like to have: if a in range(48.35, 48.45, 0.1): ... print 'In limits' ... else: ... print 'Out of limits' ... lookAtRange(40) In limits lookAtRange(50) In limits lookAtRange(20) Out of limits lookAtRange(120) Out of limits Johan _ From: Andre Engels [mailto:[EMAIL PROTECTED] Sent: 08 February 2007 07:17 PM To: [EMAIL PROTECTED] Cc: tutor@python.org Subject: Re: [Tutor] Range of float value 2007/2/8, Johan Geldenhuys HYPERLINK mailto:[EMAIL PROTECTED][EMAIL PROTECTED]: Hi all, I have a value that ranges between 48.01 and 48.57. a Float value in other words. I want to look at changes in the value. If my normal range is between 48.35 and 48.45, how will I identify the value below 48.35 and above 48.45? Something I tried was: for a in range(48.35, 48.45): print a It gives me a value of 100. Is it possible to get a range of a float value? It depends. What would you like it to be? All numbers in that range? They're uncountably infinite, so no way we could ever get that out of the computer. All actual float values? Depends too much on the implementation of the specific machine you're working on to be workable. Identifying values below 48.35 and above 48.45 is simply done by: if value 48.35 or value 48.45 then... No need to first create the range of values -- Andre Engels, HYPERLINK mailto:[EMAIL PROTECTED][EMAIL PROTECTED] ICQ: 6260644 -- Skype: a_engels -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.17.30/674 - Release Date: 2007/02/07 03:33 PM -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.17.30/674 - Release Date: 2007/02/07 03:33 PM ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Range of float value
Johan Geldenhuys wrote: OK, this what I wanted: I have a value: a = 48.41 My lowValue is: lowValue = 48.35 My highValue is : highvalue = 48.45 if a = lowValue: print 'value below limit' if a = highValue: print value above limit' I though that it could be possible to have a range between 48.35 and 48.45 that could have a step of 0.1 What is wrong with def lookAtRange(a): if lowValue = a = highValue: print 'In limits' ..etc ?? This works fine with normal intgers: * def lookAtRange(a): ... if a in range(40, 110, 10):*#Would like to have: if a in range(48.35, 48.45, 0.1): *... print 'In limits' ... else: ... print 'Out of limits' ... lookAtRange(40) In limits lookAtRange(50) In limits lookAtRange(20) Out of limits lookAtRange(120) Out of limits * Are you sure this is what you want? Have you tried lookAtRange(45) for example? The range function creates a list of integers: In [1]: range(40, 110, 10) Out[1]: [40, 50, 60, 70, 80, 90, 100] The 'in' operator tests for membership. 40 is in the list; 20 and 45 are not. I think even in the case of integers the range test with is what you want. Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Range of float value
On Thu, 8 Feb 2007, Johan Geldenhuys wrote: OK, this what I wanted: I have a value: a = 48.41 My lowValue is: lowValue = 48.35 My highValue is : highvalue = 48.45 Range does not work on floats: it's meant to work on integers. I though that it could be possible to have a range between 48.35 and 48.45 that could have a step of 0.1 There's an unsafe assumption here: in general, comparing floats for equality won't work unless you are very very careful. See: http://www.python.org/doc/tut/node16.html Because floats aren't directly comparable (at least under normal cases), that negates the idea of build a list of floats and comparing for equality against one of them. However, Kent mentioned a solution that should work better, a chained comparison: a = b = c which is true if b is squeezed between a and b. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
