On 2014/11/19, 1:03 PM, Benjamin Root wrote: > What you are seeing is the fact that the adjacent cells share the same > coordinates, so neighboring cells overlap by one pixel. This is only > visible when alpha != 1. This is a tricky issue to solve, but I could > have sworn we made some progress on that front by setting "snap" to > False somewhere. There have been past discussions about it, for sure...
I don't think we ever made any progress; it seems like a problem with the renderer itself, agg in this case, and one that differs from one renderer to another (e.g., if the plot is saved as pdf and then rendered by different libraries). Try turning off antialiasing. Eric > > Ben Root > > On Wed, Nov 19, 2014 at 12:57 PM, Loïc Estève <loic.est...@inria.fr > <mailto:loic.est...@inria.fr>> wrote: > > Thanks for the suggestions, I have tried the easiest one for now, > namely pcolormesh, see attached plot. The alpha colormap look great > but I can't seem to figure out how to prevent the edges of the cells > from being visible. I tried using edgecolors='none' to no avail. I > guess retrospectively that is similar to the lines we see in the > colormap on the right. > > The snippet I am using: > > import numpy as np > > import matplotlib.pyplot as plt > from matplotlib.colors import LinearSegmentedColormap > > import matplotlib > > matplotlib.rcParams['figure.__facecolor'] = 'white' > > cm_dict = {'red': ((0.0, 1.0, 1.0), > (1.0, 1.0, 1.0)), > 'green': ((0.0, 0.0, 0.0), > (1.0, 0.0, 0.0)), > 'blue': ((0.0, 0.0, 0.0), > (1.0, 0.0, 0.0)), > 'alpha': ((0.0, 0.0, 0.0), > (1.0, 1.0, 1.0)) > } > > my_cm = LinearSegmentedColormap('my___cm', cm_dict) > > vals = np.tile(np.linspace(-1, 1, 30), (20, 1)) > > fig = plt.figure() > ax = plt.pcolormesh(vals, cmap=my_cm) > plt.colorbar() > plt.show() > > Cheers, > Loïc > > > > > ------------------------------------------------------------------------------ > Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server > from Actuate! Instantly Supercharge Your Business Reports and Dashboards > with Interactivity, Sharing, Native Excel Exports, App Integration & more > Get technology previously reserved for billion-dollar corporations, FREE > http://pubads.g.doubleclick.net/gampad/clk?id=157005751&iu=/4140/ostg.clktrk > > > > _______________________________________________ > Matplotlib-users mailing list > Matplotlib-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/matplotlib-users > ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=157005751&iu=/4140/ostg.clktrk _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
