Re: [Matplotlib-users] Histogram align 'edge' or 'center' bug?
On Sun, 2007-04-08 at 19:25 +0200, David Fokkema wrote: On Fri, 2007-04-06 at 18:32 +0300, Jouni K. Seppänen wrote: David Fokkema [EMAIL PROTECTED] writes: If I choose center, the result is that my histogram is calculated for edge values but the bars are placed at center values which is completely misleading and wrong! I'd say this is a bug, but I may be overlooking something here... Looks like a bug to me. Could you file it at http://sf.net/tracker/?group_id=80706atid=560720 so it isn't forgotten? Well... It couldn't be too hard to fix, I guess... I know python, I tracked down the source, I could try and fix it, right? I think I'll have the time next Tuesday, so hopefully I'll file a bug report with an attached patch, ;-) I fixed the bug, I think. At least it's working on my system and I think it is not invasive. Comments please? I'll send it upstream otherwise... --- matplotlib/axes.py.orig 2007-04-10 10:58:30.0 +0200 +++ matplotlib/axes.py 2007-04-10 11:14:56.0 +0200 @@ -4149,7 +4149,7 @@ hist bars if not self._hold: self.cla() -n, bins = matplotlib.mlab.hist(x, bins, normed) +n, bins = matplotlib.mlab.hist(x, bins, normed, align) if width is None: width = 0.9*(bins[1]-bins[0]) if orientation == 'horizontal': patches = self.barh(bins, n, height=width, left=bottom, align=align) --- matplotlib/mlab.py.orig 2007-04-10 11:16:23.0 +0200 +++ matplotlib/mlab.py 2007-04-10 11:24:48.0 +0200 @@ -597,7 +597,7 @@ #S = -1.0*asum(p*log(p)) return S -def hist(y, bins=10, normed=0): +def hist(y, bins=10, normed=0, align='edge'): Return the histogram of y with bins equally sized bins. If bins is an array, use the bins. Return value is @@ -626,11 +626,16 @@ dy = (ymax-ymin)/bins bins = ymin + dy*arange(bins) +if align == 'center': + hw = .5*(bins[1]-bins[0]) + nbins = [x-hw for x in bins] +else: + nbins = bins -n = searchsorted(sort(y), bins) +n = searchsorted(sort(y), nbins) n = diff(concatenate([n, [len(y)]])) if normed: - db = bins[1]-bins[0] + db = nbins[1]-nbins[0] return 1/(len(y)*db)*n, bins else: return n, bins Thanks, David - Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.phpp=sourceforgeCID=DEVDEV ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] Histogram align 'edge' or 'center' bug?
David Fokkema [EMAIL PROTECTED] writes: I fixed the bug, I think. At least it's working on my system and I think it is not invasive. Comments please? I'll send it upstream otherwise... Does this handle the case where the user has specified bins of different widths? It looks like you are only using the width of the first bin: +if align == 'center': + hw = .5*(bins[1]-bins[0]) + nbins = [x-hw for x in bins] +else: + nbins = bins At least, I've always thought that unequal bins are allowed, but from the following it seems that the probability density support also makes an incompatible assumption: if normed: - db = bins[1]-bins[0] + db = nbins[1]-nbins[0] return 1/(len(y)*db)*n, bins -- Jouni K. Seppänen http://www.iki.fi/jks - Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.phpp=sourceforgeCID=DEVDEV ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] Histogram align 'edge' or 'center' bug?
On Tue, 2007-04-10 at 16:13 +0300, Jouni K. Seppänen wrote: David Fokkema [EMAIL PROTECTED] writes: I fixed the bug, I think. At least it's working on my system and I think it is not invasive. Comments please? I'll send it upstream otherwise... Does this handle the case where the user has specified bins of different widths? It looks like you are only using the width of the first bin: +if align == 'center': + hw = .5*(bins[1]-bins[0]) + nbins = [x-hw for x in bins] +else: + nbins = bins I am only using the first width, indeed. If different widths are allowed (and why not?) some more coding has to be done. On the other hand, I use align = 'center' because I have a detector which samples timing information at 20 ns intervals. So, when binning timing information, I only have 0, 20 ns, 40 ns, 60 ns and so forth. Being able to specify those values as the center of my bin instead of calculating edges myself (-10, 10, 30, 50, etc.) is very useful. I can't think of an application where you have bins of different widths and you want to center the values... Furthermore, when plotting the histogram, the function calculates the width of the bars only for the first bin and uses that for all bars. So I think this function is highly unstable when you use variable sized bins. Matplotlib.mlab.hist only calculates the histogram and can only use variable sized bins when you want a simple histogram. Maybe add something to this effect in the docstring? At least, I've always thought that unequal bins are allowed, but from the following it seems that the probability density support also makes an incompatible assumption: if normed: - db = bins[1]-bins[0] + db = nbins[1]-nbins[0] return 1/(len(y)*db)*n, bins It does... David - Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.phpp=sourceforgeCID=DEVDEV ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] Histogram align 'edge' or 'center' bug?
David Fokkema [EMAIL PROTECTED] writes: I can't think of an application where you have bins of different widths and you want to center the values... Actually, now that I think about it, there is not enough information in the bin centers to know the widths of the bins if they may vary. For example, if your bin edges are (2, 4, 8, 16, 32) or (1, 5, 7, 17, 31), you get the same bin centers (3, 6, 12, 24). Perhaps it's best to disallow variable-width bins when align='center'. -- Jouni K. Seppänen http://www.iki.fi/jks - Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.phpp=sourceforgeCID=DEVDEV ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] Histogram align 'edge' or 'center' bug?
On Fri, 2007-04-06 at 18:32 +0300, Jouni K. Seppänen wrote: David Fokkema [EMAIL PROTECTED] writes: If I choose center, the result is that my histogram is calculated for edge values but the bars are placed at center values which is completely misleading and wrong! I'd say this is a bug, but I may be overlooking something here... Looks like a bug to me. Could you file it at http://sf.net/tracker/?group_id=80706atid=560720 so it isn't forgotten? Well... It couldn't be too hard to fix, I guess... I know python, I tracked down the source, I could try and fix it, right? I think I'll have the time next Tuesday, so hopefully I'll file a bug report with an attached patch, ;-) - Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.phpp=sourceforgeCID=DEVDEV ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] Histogram align 'edge' or 'center' bug?
David Fokkema [EMAIL PROTECTED] writes: If I choose center, the result is that my histogram is calculated for edge values but the bars are placed at center values which is completely misleading and wrong! I'd say this is a bug, but I may be overlooking something here... Looks like a bug to me. Could you file it at http://sf.net/tracker/?group_id=80706atid=560720 so it isn't forgotten? -- Jouni K. Seppänen http://www.iki.fi/jks - Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.phpp=sourceforgeCID=DEVDEV ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
[Matplotlib-users] Histogram align 'edge' or 'center' bug?
Hi group, I have the following ipython 'session': In [23]: data = [0, 0.4, 0.6, 1, 2, 3] In [24]: bins = [0, 1, 2, 3] In [25]: hist(data, bins, align='edge') Out[25]: (array([3, 1, 1, 1]), [0, 1, 2, 3], a list of 4 Patch objects) In [26]: hist(data, bins, align='center') Out[26]: (array([3, 1, 1, 1]), [0, 1, 2, 3], a list of 4 Patch objects) I would suspect that the histogram output from 'center' should be [2, 2, 1, 1]. Why is this not so? At least, the two should be different? I would say that with edge, my bins would be 0-1, 1-2, 2-3, 3-4, and that center should give me -0.5-0.5, 0.5-1.5, 1.5-2.5, 2.5-3.5, but this seems not to be the case??? Any help understanding this would be greatly appreciated! Thanks, David - Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.phpp=sourceforgeCID=DEVDEV ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] Histogram align 'edge' or 'center' bug?
On Wed, 2007-04-04 at 16:26 +0200, David Fokkema wrote: Hi group, I have the following ipython 'session': In [23]: data = [0, 0.4, 0.6, 1, 2, 3] In [24]: bins = [0, 1, 2, 3] In [25]: hist(data, bins, align='edge') Out[25]: (array([3, 1, 1, 1]), [0, 1, 2, 3], a list of 4 Patch objects) In [26]: hist(data, bins, align='center') Out[26]: (array([3, 1, 1, 1]), [0, 1, 2, 3], a list of 4 Patch objects) I would suspect that the histogram output from 'center' should be [2, 2, 1, 1]. Why is this not so? At least, the two should be different? I would say that with edge, my bins would be 0-1, 1-2, 2-3, 3-4, and that center should give me -0.5-0.5, 0.5-1.5, 1.5-2.5, 2.5-3.5, but this seems not to be the case??? Any help understanding this would be greatly appreciated! It seems that the hist function simply calls matplotlib.mlab.hist without any regard to the bins (be they edge or centered values) and passes the plotting through to the 'bar' function. This function places the bar with either the edge at the bin value or the center at the bin value. If I choose center, the result is that my histogram is calculated for edge values but the bars are placed at center values which is completely misleading and wrong! I'd say this is a bug, but I may be overlooking something here... Thanks, David Thanks, David - Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.phpp=sourceforgeCID=DEVDEV ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users - Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.phpp=sourceforgeCID=DEVDEV ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
