Furthermore, I think there is some work being done to add functionality to the Norm to allow specifying a middle value along with a vmin and a vmax. Ben Root On Fri, Jun 5, 2015 at 3:20 PM, Eric Firing <ef...@ha...> wrote: > On 2015年06月05日 8:17 AM, Sourish Basu wrote: > > Very often the "zero" of an anomaly is not at the center of the extrema, > > and requires creating a custom diverging colormap anyway (see attached > > example). > > Reminder: in matplotlib, color mapping is done with the combination of a > colormap and a norm. This allows one to design a norm to handle the > mapping, including any nonlinearity or difference between the handling > of positive and negative values. This is more general than customizing > a colormap; once you have a norm to suit your purpose, you can use it > with any colormap. > > Maybe this is actually what you are already doing, but I wanted to point > it out here in case some readers are not familiar with this > colormap+norm strategy. > > Eric > > > ------------------------------------------------------------------------------ > _______________________________________________ > Matplotlib-users mailing list > Mat...@li... > https://lists.sourceforge.net/lists/listinfo/matplotlib-users >
<html> <head> <meta content="text/html; charset=utf-8" http-equiv="Content-Type"> </head> <body bgcolor="#FFFFFF" text="#000000"> <div class="moz-cite-prefix">On 06/05/2015 01:20 PM, Eric Firing wrote: </div> <blockquote cite="mid:557...@ha..." type="cite"> <pre wrap=""> Reminder: in matplotlib, color mapping is done with the combination of a colormap and a norm. This allows one to design a norm to handle the mapping, including any nonlinearity or difference between the handling of positive and negative values. This is more general than customizing a colormap; once you have a norm to suit your purpose, you can use it with any colormap. Maybe this is actually what you are already doing, but I wanted to point it out here in case some readers are not familiar with this colormap+norm strategy.</pre> </blockquote> <br> Actually, I didn't use norms because I never quite figured out how to use them or how to make my own. If there's a way to create a norm with a custom mid-point, I'd love to know/use that.<br> <br> -Sourish<br> <br> <blockquote cite="mid:557...@ha..." type="cite"> <pre wrap=""> Eric ------------------------------------------------------------------------------ _______________________________________________ Matplotlib-users mailing list <a class="moz-txt-link-abbreviated" href="mailto:Mat...@li...">Mat...@li...</a> <a class="moz-txt-link-freetext" href="https://lists.sourceforge.net/lists/listinfo/matplotlib-users">https://lists.sourceforge.net/lists/listinfo/matplotlib-users</a> </pre> </blockquote> <br> <br> <div class="moz-signature">-- <br> <b>Q:</b> What if you strapped C4 to a boomerang? Could this be an effective weapon, or would it be as stupid as it sounds?<br> <b>A:</b> Aerodynamics aside, I’m curious what tactical advantage you’re expecting to gain by having the high explosive fly back at you if it misses the target.<br> </div> </body> </html>
Not to plug one of my own answers to much, but here's a basic example. http://stackoverflow.com/questions/20144529/shifted-colorbar-matplotlib I've been meeting to submit a PR with a more full featured version for a few years now, but haven't. On Jun 5, 2015 4:45 PM, "Sourish Basu" <sou...@gm...> wrote: > On 06/05/2015 01:20 PM, Eric Firing wrote: > > > Reminder: in matplotlib, color mapping is done with the combination of a > colormap and a norm. This allows one to design a norm to handle the > mapping, including any nonlinearity or difference between the handling > of positive and negative values. This is more general than customizing > a colormap; once you have a norm to suit your purpose, you can use it > with any colormap. > > Maybe this is actually what you are already doing, but I wanted to point > it out here in case some readers are not familiar with this > colormap+norm strategy. > > > Actually, I didn't use norms because I never quite figured out how to use > them or how to make my own. If there's a way to create a norm with a custom > mid-point, I'd love to know/use that. > > -Sourish > > > > Eric > > ------------------------------------------------------------------------------ > _______________________________________________ > Matplotlib-users mailing lis...@li...https://lists.sourceforge.net/lists/listinfo/matplotlib-users > > > > -- > *Q:* What if you strapped C4 to a boomerang? Could this be an effective > weapon, or would it be as stupid as it sounds? > *A:* Aerodynamics aside, I’m curious what tactical advantage you’re > expecting to gain by having the high explosive fly back at you if it misses > the target. > > > ------------------------------------------------------------------------------ > > _______________________________________________ > Matplotlib-users mailing list > Mat...@li... > https://lists.sourceforge.net/lists/listinfo/matplotlib-users > >
<html> <head> <meta content="text/html; charset=utf-8" http-equiv="Content-Type"> </head> <body bgcolor="#FFFFFF" text="#000000"> <div class="moz-cite-prefix"><br> On 06/05/2015 03:57 PM, Joe Kington wrote:<br> </div> <blockquote cite="mid:CAC...@ma..." type="cite"> <p dir="ltr">Not to plug one of my own answers to much, but here's a basic example. <a moz-do-not-send="true" href="http://stackoverflow.com/questions/20144529/shifted-colorbar-matplotlib">http://stackoverflow.com/questions/20144529/shifted-colorbar-matplotlib</a></p> <p dir="ltr">I've been meeting to submit a PR with a more full featured version for a few years now, but haven't.</p> </blockquote> <br> This is great, but it has a slightly bothersome side effect on the colorbar ticks. In your original example, I changed the line 'data = 10 * (data - 0.8)' to 'data = 10 * (data - 0.85)', so that the numbers are now in between -8.5 and +1.5. As a result, when the colorbar is drawn, you get a tick at -8, as well as one at -9 (similarly at +1 and +2). Example attached. As in, the colorbar method seems intent on adding those tick marks at -9 and +2. The result is not aesthetically pleasing.<br> <br> In one of my real-data example, the minimum value of the data happened to be -4.003, and as a result there was a tick label at -4 and an overlapping tick label at -5. Why does this happen only when I specify 'norm' in imshow? How do I get matplotlib to not do that?<br> <br> Thanks,<br> Sourish<br> <br> <blockquote cite="mid:CAC...@ma..." type="cite"> <div class="gmail_quote">On Jun 5, 2015 4:45 PM, "Sourish Basu" <<a moz-do-not-send="true" href="mailto:sou...@gm...">sou...@gm...</a>> wrote:<br type="attribution"> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> <div bgcolor="#FFFFFF" text="#000000"> <div>On 06/05/2015 01:20 PM, Eric Firing wrote: </div> <blockquote type="cite"> <pre>Reminder: in matplotlib, color mapping is done with the combination of a colormap and a norm. This allows one to design a norm to handle the mapping, including any nonlinearity or difference between the handling of positive and negative values. This is more general than customizing a colormap; once you have a norm to suit your purpose, you can use it with any colormap. Maybe this is actually what you are already doing, but I wanted to point it out here in case some readers are not familiar with this colormap+norm strategy.</pre> </blockquote> <br> Actually, I didn't use norms because I never quite figured out how to use them or how to make my own. If there's a way to create a norm with a custom mid-point, I'd love to know/use that.<br> <br> -Sourish<br> <br> <blockquote type="cite"> <pre> Eric ------------------------------------------------------------------------------ _______________________________________________ Matplotlib-users mailing list <a moz-do-not-send="true" href="mailto:Mat...@li..." target="_blank">Mat...@li...</a> <a moz-do-not-send="true" href="https://lists.sourceforge.net/lists/listinfo/matplotlib-users" target="_blank">https://lists.sourceforge.net/lists/listinfo/matplotlib-users</a> </pre> </blockquote> <br> <br> <div>-- <br> <b>Q:</b> What if you strapped C4 to a boomerang? Could this be an effective weapon, or would it be as stupid as it sounds?<br> <b>A:</b> Aerodynamics aside, I’m curious what tactical advantage you’re expecting to gain by having the high explosive fly back at you if it misses the target.<br> </div> </div> <br> ------------------------------------------------------------------------------<br> <br> _______________________________________________<br> Matplotlib-users mailing list<br> <a moz-do-not-send="true" href="mailto:Mat...@li...">Mat...@li...</a><br> <a moz-do-not-send="true" href="https://lists.sourceforge.net/lists/listinfo/matplotlib-users" target="_blank">https://lists.sourceforge.net/lists/listinfo/matplotlib-users</a><br> <br> </blockquote> </div> </blockquote> <br> <br> <div class="moz-signature">-- <br> <b>Q:</b> What if you strapped C4 to a boomerang? Could this be an effective weapon, or would it be as stupid as it sounds?<br> <b>A:</b> Aerodynamics aside, I’m curious what tactical advantage you’re expecting to gain by having the high explosive fly back at you if it misses the target.<br> </div> </body> </html>