> On 5 Jun 2015, at 9:27 AM, Thomas Caswell <tcasw...@gmail.com> wrote: > > Jody, > > This has come up before and the consensus seemed to be that for the anomaly > data sets knowing where the zero is is very important and the default color > limits will probably get that wrong. So long as the user has to set the > limits, they can also select one of the diverging color maps.
OK, fair enough - if the consensus is that people who want diverging colormaps need to know what they are doing, and the default is only for sequential data, then that argument has merit. I do not look forward to seeing the first student talks that try to contour velocity data using one of these colormaps, but maybe the results will be so ghastly the naive user will realize they need to do something more appropriate. However, if sequential is what you have decided, then it is useful to say how the underlying data is distributed: For uniform distributions like those used in the plotted examples, I *prefer* C and D. However, for data like that in the movies, which look to be more Gaussian, I would actually prefer B, or a version of D that went to black and white to better represent the extreme values. Put another way, I’d use A and B, but most of the time I’d set my data limits so that they didn’t saturate as much as they do in the plotted examples. Hopefully that makes sense. Cheers, Jody > I also advocate for users/domains which typically plot anomaly/diverging data > sets to write helper functions like > > def im_diverging(ax, data, cmap='RbBu', *args, **kwargs): > limits = some_limit_function(data) > return ax.imshow(data, cmap=cmap, vmin=limits[0], vmax=limits[1], *args, > **kwargs) > > Tom > > On Fri, Jun 5, 2015 at 12:18 PM Jody Klymak <jkly...@uvic.ca > <mailto:jkly...@uvic.ca>> wrote: > Hi, > > This is a great initiative, I love colormaps and am always disatisfied. > > However, I am concerned about these proposed defaults. As Ben says, there > are two types of data sets: “intensity” or “density” data, and data sets with > a natural zero (i.e. positive or negative anomaly or velocity). I’d be fine > with any of the proposed colormaps for “intensity” data sets, but I would > *never* use them for anomaly data sets; I couldn’t tell where the middle > (zero) of any of those colormaps are intuitively. > > Jet and parula, for all their sins, are decent compromises for the naive user > (or the user in a rush) because they do a good job of representing both types > of data. Even in black and white jet does something reasonable, which is go > to dark at extreme values and white-ish in the middle. Jet also has a nice > central green hue between blue and yellow that signals zero (or at least it > does to me after years of looking at it). I don’t see that jet really loses > that under colorblindness; in fact I almost prefer the “Moderate Deuter” > version of jet to the actual jet. > > Anyways, I guess I am advocating trying to find a colormap with a very > obvious central hue to represent zero. Anomaly data sets are *very* common, > so having a default colormap that doesn’t do something reasonable with them > may be a turn off to new users. > > Cheers, Jody > > > >> On 5 Jun 2015, at 8:36 AM, Benjamin Root <ben.r...@ou.edu >> <mailto:ben.r...@ou.edu>> wrote: >> >> It is funny that you mention that you prefer the warmer colors over the >> cooler colors. There has been some back-n-forth about which is better. I >> personally have found myself adverse to using just cool or just warm colors, >> preferring a mix of cool and warm colors. Perhaps it is my background in >> meteorology and viewing temperature maps? >> >> Another place where a mix of cool and warm colors are useful is for severity >> indications such as radar maps. It is no accident that radar maps are >> colored greens and blues for weak precipitation, then yellow for heavier, >> and then reds for heaviest (possibly severe) precipitation -- it came from >> the old FAA color guides. While we all know that that colormap is >> fundamentally flawed, there was a rationale behind it. >> >> Hopefully I will have some time today to play around with the D option. I >> want to see if I can shift the curve a bit to include more yellows and >> orange so that it can have a mix of cool and warm colors. >> >> Ben Root >> >> >> On Fri, Jun 5, 2015 at 11:21 AM, Philipp A. <flying-sh...@web.de >> <mailto:flying-sh...@web.de>> wrote: >> I vote for A and B. Only B if i get just one vote. >> >> C is too washed out and i like the warm colors more than the cold ones in D. >> >> It’s funny that this comes up while I’m handling colormaps in my own work at >> the moment. >> >> Neal Becker <ndbeck...@gmail.com <mailto:ndbeck...@gmail.com>> schrieb am >> Fr., 5. Juni 2015 um 12:58 Uhr: >> I vote for D, although I like matlab's new default even better >> >> >> ------------------------------------------------------------------------------ >> _______________________________________________ >> Matplotlib-users mailing list >> Matplotlib-users@lists.sourceforge.net >> <mailto:Matplotlib-users@lists.sourceforge.net> >> https://lists.sourceforge.net/lists/listinfo/matplotlib-users >> <https://lists.sourceforge.net/lists/listinfo/matplotlib-users> >> >> ------------------------------------------------------------------------------ >> >> _______________________________________________ >> Matplotlib-users mailing list >> Matplotlib-users@lists.sourceforge.net >> <mailto:Matplotlib-users@lists.sourceforge.net> >> https://lists.sourceforge.net/lists/listinfo/matplotlib-users >> <https://lists.sourceforge.net/lists/listinfo/matplotlib-users> >> >> >> ------------------------------------------------------------------------------ >> _______________________________________________ >> Matplotlib-users mailing list >> Matplotlib-users@lists.sourceforge.net >> <mailto:Matplotlib-users@lists.sourceforge.net> >> https://lists.sourceforge.net/lists/listinfo/matplotlib-users >> <https://lists.sourceforge.net/lists/listinfo/matplotlib-users> > > -- > Jody Klymak > http://web.uvic.ca/~jklymak/ <http://web.uvic.ca/~jklymak/> > > > > > > ------------------------------------------------------------------------------ > _______________________________________________ > Matplotlib-users mailing list > Matplotlib-users@lists.sourceforge.net > <mailto:Matplotlib-users@lists.sourceforge.net> > https://lists.sourceforge.net/lists/listinfo/matplotlib-users > <https://lists.sourceforge.net/lists/listinfo/matplotlib-users> -- Jody Klymak http://web.uvic.ca/~jklymak/
------------------------------------------------------------------------------
_______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
