Thanks I'll give this a try. numpy.min(grid) reports 0.0 (no negative) yet it labels as -0.0, BTW, but let me give this a try.
Bruce --------------------------------------- Bruce W. Ford Clear Science, Inc. br...@clearscienceinc.com http://www.ClearScienceInc.com http://www.facebook.com/clearscience http://www.twitter.com/ROVs_rule Phone: (904) 796-8101 Fax: (904) 379-9704 8241 Parkridge Circle N. Jacksonville, FL 32211 Skype: bruce.w.ford --------------------------------------- To schedule a meeting with Bruce, Go to: http://tungle.me/bruceford ---------------------------------------- On Fri, Aug 20, 2010 at 4:44 PM, Eric Firing <efir...@hawaii.edu> wrote: > On 08/20/2010 10:14 AM, Bruce Ford wrote: >> This effect is happening within an web app that displays gridded >> fields from multiple datasets (~4500 lines of code). So I it's tricky >> to create an example. Although if I use numpy.min(grid) the minimum >> is 0. So, I think colorbar or matplotlib is interpreting the 0 as -0. > > > You are talking about the colorbar tick labels, correct? The lowest > tick label is coming out as -0.0? > > >> (Matplotlib version 0.99.0 RC0) >> >> The colorbar call that I'm using is: >> >> cbar = pyplot.colorbar(plot,shrink=0.7, format="%1.1f", >> spacing='proportional',orientation='vertical') > > This means your colorbar tick values are simply being formatted by > python, like this: > > In [1]: "%1.1f" % -0.0000001 > Out[1]: '-0.0' > > In [2]: "%1.1f" % 0.0000001 > Out[2]: '0.0' > > In [3]: "%1.1f" % 0.0 > Out[3]: '0.0' > > In [4]: "%1.1f" % -0.0 > Out[4]: '-0.0' > > In [5]: import numpy > > In [6]: numpy.min(-0.0) > Out[6]: -0 > > In [7]: -0.0 == 0.0 > Out[7]: True > > > So I suspect the problem is that a small negative value, or a negative > zero, is becoming the tick value. I don't know why. You may or may not > want to investigate. > > I dimly recall a problem like this cropping up on the list before--but I > don't remember anything else about it. > > Here is a workaround (untested, but should be close): > > from matplotlib.ticker import FormatStrFormatter > class MyCBFormatter(FormatStrFormatter): > def __call__(self, x, pos=None): > xstr = self.fmt % x > if float(xstr) == 0: > return self.fmt % 0 > return xstr > cbar = pyplot.colorbar(plot,shrink=0.7, format=MyCBFormatter("%1.1f"), > spacing='proportional',orientation='vertical') > > > Eric > >> >> cbar.ax.set_ylabel(cbar_label(param,unit)) >> >> The function cbar_label is: >> >> def cbar_label(param,unit): >> #Helper function for making colorbar label >> if param == "sig": >> if unit==1: >> cbar_label = "Feet" >> else: >> cbar_label = "Meters" >> elif param == "dir": >> cbar_label = "Radial Direction" >> elif param == "per": >> cbar_label = "Seconds" >> elif param[-5:] == "_wind": >> if unit == 3: >> cbar_label = "Kts" >> else: >> cbar_label = "M/S" >> elif param[-4:] == "_hgt": >> if unit == 5: >> cbar_label = "GPFt" >> else: >> cbar_label = "GPM" >> elif param == "slp": >> cbar_label = "Millibars" >> elif param == "1000_rh": >> cbar_label = "%" >> elif param == "1000_temp": >> if unit == 9: >> cbar_label = "Degrees F" >> else: >> cbar_label = "Degrees C" >> else: >> cbar_label = param >> return cbar_label >> >> If this doesn't offer anything, I'll try to generate a >> compartmentalized example of the issue. >> >> Bruce > > ------------------------------------------------------------------------------ > This SF.net email is sponsored by > > Make an app they can't live without > Enter the BlackBerry Developer Challenge > http://p.sf.net/sfu/RIM-dev2dev > _______________________________________________ > Matplotlib-users mailing list > Matplotlib-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/matplotlib-users > ------------------------------------------------------------------------------ This SF.net email is sponsored by Make an app they can't live without Enter the BlackBerry Developer Challenge http://p.sf.net/sfu/RIM-dev2dev _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
