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## matplotlib-users

 [Matplotlib-users] scientific notation in ticklabels for linear plot From: Jonathan Slavin - 2010-10-18 18:43:51 Hi, I'm wondering if there's some relatively automatic way to have the ticklabels to come out in scientific notation for an axis that uses a linear scale (and has a range that warrants scientific notation)? For example, an axis that goes from 0 to 2.E18 by default uses the labels 0, 0.5, 1.0, 1.5, 2.0 and puts 1e18 at the end of the axis. To me this is unappealing. 1e18 is a computer programming way to write the 10^{18} (in LaTeX formatting). In IDL the ticklabels are 5.0x10^{17}, 1.0x10^{18}, 1.5x10^{18}, 2.0x10^{18}. This is one instance where I think IDL gets it right and matplotlib gets it wrong. So, as far as I can tell, one can give the ticklabels by hand, and so I could achieve my desired labels that way, but it'd be nice to have a more automatic way to do it. Searching the examples, I've come up empty so far. I would also advocate changing the default format for labeling axes that fall in this category. Do the developers have any opinions on this? Regards, Jon 
 Re: [Matplotlib-users] scientific notation in ticklabels for linear plot From: Friedrich Romstedt - 2010-10-19 17:08:13 2010/10/18 Jonathan Slavin : > I'm wondering if there's some relatively automatic way to have the > ticklabels to come out in scientific notation for an axis that uses a > linear scale (and has a range that warrants scientific notation)?  For > example, an axis that goes from 0 to 2.E18 by default uses the labels 0, > 0.5, 1.0, 1.5, 2.0 and puts 1e18 at the end of the axis.  To me this is > unappealing. 1e18 is a computer programming way to write the 10^{18} (in > LaTeX formatting).  In IDL the ticklabels are 5.0x10^{17}, 1.0x10^{18}, > 1.5x10^{18}, 2.0x10^{18}.  This is one instance where I think IDL gets > it right and matplotlib gets it wrong.  So, as far as I can tell, one > can give the ticklabels by hand, and so I could achieve my desired > labels that way, but it'd be nice to have a more automatic way to do it. > Searching the examples, I've come up empty so far.  I would also > advocate changing the default format for labeling axes that fall in this > category.  Do the developers have any opinions on this? There's a thread some monthes ago about this, I provided code to do this. Currently, this Formatter class didn't make it into matplotlib due a lack of providing a patch by me. If others agree that this would be a good feature, I'll clean the code if necessary and provide another patch for this. Looking for the thread ... http://article.gmane.org/gmane.comp.python.matplotlib.general/23824/match=scientific+notation+friedrich IIRC, the formatter class does NOT provide automatic choice of appropriate exponent, i.e. you have to provide this in instantiation time. hth, and let me know about any progress, Friedrich P.S.: I just gave the thread link and didn't look into it further. But it should be the message I remembered. 
 Re: [Matplotlib-users] scientific notation in ticklabels for linear plot From: David Pine - 2010-10-19 18:46:18 I agree with Jonathan and would very much like to see this feature implemented. The example shown in the thread didn't show the "×" symbol, however, which would be nice to have -- e.g. it should read 2.0 × 10² rather than 2.0 10². David On Oct 19, 2010, at 1:08 PM, Friedrich Romstedt wrote: > 2010/10/18 Jonathan Slavin : >> I'm wondering if there's some relatively automatic way to have the >> ticklabels to come out in scientific notation for an axis that uses a >> linear scale (and has a range that warrants scientific notation)? For >> example, an axis that goes from 0 to 2.E18 by default uses the labels 0, >> 0.5, 1.0, 1.5, 2.0 and puts 1e18 at the end of the axis. To me this is >> unappealing. 1e18 is a computer programming way to write the 10^{18} (in >> LaTeX formatting). In IDL the ticklabels are 5.0x10^{17}, 1.0x10^{18}, >> 1.5x10^{18}, 2.0x10^{18}. This is one instance where I think IDL gets >> it right and matplotlib gets it wrong. So, as far as I can tell, one >> can give the ticklabels by hand, and so I could achieve my desired >> labels that way, but it'd be nice to have a more automatic way to do it. >> Searching the examples, I've come up empty so far. I would also >> advocate changing the default format for labeling axes that fall in this >> category. Do the developers have any opinions on this? > > There's a thread some monthes ago about this, I provided code to do > this. Currently, this Formatter class didn't make it into matplotlib > due a lack of providing a patch by me. If others agree that this > would be a good feature, I'll clean the code if necessary and provide > another patch for this. > > Looking for the thread ... > http://article.gmane.org/gmane.comp.python.matplotlib.general/23824/match=scientific+notation+friedrich > > IIRC, the formatter class does NOT provide automatic choice of > appropriate exponent, i.e. you have to provide this in instantiation > time. > > hth, and let me know about any progress, > Friedrich > > P.S.: I just gave the thread link and didn't look into it further. > But it should be the message I remembered. > > ------------------------------------------------------------------------------ > Download new Adobe(R) Flash(R) Builder(TM) 4 > The new Adobe(R) Flex(R) 4 and Flash(R) Builder(TM) 4 (formerly > Flex(R) Builder(TM)) enable the development of rich applications that run > across multiple browsers and platforms. Download your free trials today! > http://p.sf.net/sfu/adobe-dev2dev > _______________________________________________ > Matplotlib-users mailing list > Matplotlib-users@... > https://lists.sourceforge.net/lists/listinfo/matplotlib-users 
 Re: [Matplotlib-users] scientific notation in ticklabels for linear plot From: Friedrich Romstedt - 2010-10-19 19:23:54 What about inserting \cdot, that's the scientific notation I do prefer? If I'm not mistaken that's what I did that time, might be unreadable in the preview? I checked, when you look close you see the dot in gmane preview. We can make this customisable, with \times as an alternative option. Friedrich 
 Re: [Matplotlib-users] scientific notation in ticklabels for linear plot From: David Pine - 2010-10-19 19:30:37 I like the times symbol but others prefer the dot (which I missed in the gmane preview!). So I like your suggestion of providing an option to use either \cdot or \times. David On Oct 19, 2010, at 3:23 PM, Friedrich Romstedt wrote: > What about inserting \cdot, that's the scientific notation I do prefer? > > If I'm not mistaken that's what I did that time, might be unreadable > in the preview? I checked, when you look close you see the dot in > gmane preview. > > We can make this customisable, with \times as an alternative option. > > Friedrich 
 Re: [Matplotlib-users] scientific notation in ticklabels for linear plot From: Friedrich Romstedt - 2010-10-19 19:41:35 2010/10/19 David Pine : > I like the times symbol but others prefer the dot (which I missed in the gmane preview!).  So I like your suggestion of providing an option to use either \cdot or \times. Okay, I'll try to look into it next week, is that okay with you both? I don't want to do it now since there might be more under the hood, just thinking about automatic exponent choice, I have a module for that, but it needs to pick up all the range the formatter spans over. I'd say we also have use for three other configs of the exponent choice: a) largest b) smallest c) mean d) dynamic exponent. Examples: (a) 0.001 10^2 ... 2.0 10^2 (b) 1.0 10^-1 ... 200.0 10^-1 (c) 0.01 10^1 ... 20.0 10^1 (d) 1.0 10^-1 ... 2.0 10^2 Sorry if there's some mistake but you see the principle. Also the number of digits present need to be configurable ... enough for a week. I favour (c) as the default, and 2 digits precision. Friedrich 
 Re: [Matplotlib-users] scientific notation in ticklabels for linear plot From: Jonathan Slavin - 2010-10-19 19:59:05 Friedrich, Our e-mails crossed. I don't think the numbers need to have the same exponent. I would go with (d) as my example does. The more difficult part to my mind is the number of significant digits to use. The current code that determines whether to use an offset or not must look at the number of significant digits needed to represent the ticklabels. To me what would be optimal is to, by default, use scientific notation (when the ticklabel numbers are larger or smaller than some range, say 10^3 and 10^-3) except when an offset is called for, say more than 3 significant digits are needed to represent the ticklabel numbers in scientific notation. Jon On Tue, 2010-10-19 at 21:41 +0200, Friedrich Romstedt wrote: > 2010/10/19 David Pine : > > I like the times symbol but others prefer the dot (which I missed in the gmane preview!). So I like your suggestion of providing an option to use either \cdot or \times. > > Okay, I'll try to look into it next week, is that okay with you both? > I don't want to do it now since there might be more under the hood, > just thinking about automatic exponent choice, I have a module for > that, but it needs to pick up all the range the formatter spans over. > > I'd say we also have use for three other configs of the exponent choice: > a) largest > b) smallest > c) mean > d) dynamic > exponent. > > Examples: > (a) 0.001 10^2 ... 2.0 10^2 > (b) 1.0 10^-1 ... 200.0 10^-1 > (c) 0.01 10^1 ... 20.0 10^1 > (d) 1.0 10^-1 ... 2.0 10^2 > Sorry if there's some mistake but you see the principle. > > Also the number of digits present need to be configurable ... enough for a week. > > I favour (c) as the default, and 2 digits precision. > > Friedrich -- ______________________________________________________________ Jonathan D. Slavin Harvard-Smithsonian CfA jslavin@... 60 Garden Street, MS 83 phone: (617) 496-7981 Cambridge, MA 02138-1516 cell: (781) 363-0035 USA ______________________________________________________________ 
 Re: [Matplotlib-users] scientific notation in ticklabels for linear plot From: Jonathan Slavin - 2010-10-19 19:42:47 I think that'd be fine -- i.e. the option of \cdot or \times (though in the gmane preview the dot looks a bit low). In the mean time, I came up with the method below that worked for my purpose. Jon import matplotlib.pyplot as plt import numpy as np from matplotlib.ticker import FuncFormatter def scinot(x,pos=None): if x == 0: s = '0' else: xp = int(np.floor(np.log10(np.abs(x)))) mn = x/10.**xp # Here we truncate to 2 significant digits -- may not be enough # in all cases s = '$'+str('%.1f'%mn) +'\\times 10^{'+str(xp)+'}$' return s x = np.linspace(0.,2.,10)*1.E18 y = 2.*(x/1.E18) - 1. fig = plt.figure() ax = fig.add_subplot(111) ax.plot(x,y) ax.xaxis.set_major_formatter(FucFormatter(scinot)) plt.show() On Tue, 2010-10-19 at 15:30 -0400, David Pine wrote: > I like the times symbol but others prefer the dot (which I missed in the gmane preview!). So I like your suggestion of providing an option to use either \cdot or \times. > > David > > On Oct 19, 2010, at 3:23 PM, Friedrich Romstedt wrote: > > > What about inserting \cdot, that's the scientific notation I do prefer? > > > > If I'm not mistaken that's what I did that time, might be unreadable > > in the preview? I checked, when you look close you see the dot in > > gmane preview. > > > > We can make this customisable, with \times as an alternative option. > > > > Friedrich > -- ______________________________________________________________ Jonathan D. Slavin Harvard-Smithsonian CfA jslavin@... 60 Garden Street, MS 83 phone: (617) 496-7981 Cambridge, MA 02138-1516 cell: (781) 363-0035 USA ______________________________________________________________ 
 Re: [Matplotlib-users] scientific notation in ticklabels for linear plot From: Friedrich Romstedt - 2010-10-19 19:50:24 2010/10/19 Jonathan Slavin : > I think that'd be fine -- i.e. the option of \cdot or \times (though in > the gmane preview the dot looks a bit low).  In the mean time, I came up > with the method below that worked for my purpose. Okay thx > import matplotlib.pyplot as plt > import numpy as np > from matplotlib.ticker import FuncFormatter > > def scinot(x,pos=None): >    if x == 0: >        s = '0' >    else: >        xp = int(np.floor(np.log10(np.abs(x)))) >        mn = x/10.**xp >        # Here we truncate to 2 significant digits -- may not be enough >        # in all cases >        s = '$'+str('%.1f'%mn) +'\\times 10^{'+str(xp)+'}$' >    return s > > x = np.linspace(0.,2.,10)*1.E18 > y = 2.*(x/1.E18) - 1. > fig = plt.figure() > ax = fig.add_subplot(111) > ax.plot(x,y) > ax.xaxis.set_major_formatter(FucFormatter(scinot)) typo for the records although abvious: FuncFormatter > plt.show() Okay I can do the tedious work of changing my code ASAP but with low priority ... Friedrich