Maximum bins allowed for different color brewer palettes, in choropleth?

[manubhatt3]

Please add a code sample or a nbviewer link, copy-pastable if possible

# Your code here

Problem description

Are there maximum no. of bins for different color brewer palettes in choropleth? Because if I am overriding the default 6 bins and setting it to 12, I am getting the message "Check to make sure that it is not a qualitative scheme." with some color brewer palettes.

Expected Output

Output of folium.__version__

[Conengmo]

Hi, could you share a bit more on what happened please. What was the full error? Can you share a short, self-contained code snippet that produces the same error?

[alessioarena]

Hi,
I encountered the same issue.
Each ColorBrewer colormap has a certain set of colors, for example Accent is composed of 8 colors.
You can see the full list of colors here

If you are using a specific colormap and request more bins than the individual colors you will end up with a non descriptive KeyError raised in branca

---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<ipython-input-1-5209f8da3457> in <module>
      1 import csiro_spatial as spatial
      2 data = 'test/RunDelivery/Step15 - RunEmberSimulation(LONG_TASK)/short_distance_embers_simulation_smoothed_23457de7a62.tif'
----> 3 spatial.plot.interactive(
      4     [
      5 #         (r"C:\House loss database\AireysInlet\test\RunDelivery\Input_data\CadastreParcels.shp", 'POSTCODE', 0.7, 'Reds'),

c:\house loss database\house_loss_model\libs\spatial\csiro_spatial\plot.py in interactive(data, provider, cmap, alpha, zoom, **kwargs)
    239                     # if 'bins' in kwargs:
    240                     #     colormap = _brew_colors(colormap, len(kwargs['bins']))
--> 241                     geo_j = folium.Choropleth(
    242                         geo_data=plot_d.to_json(),
    243                         data=plot_d,

~\Miniconda3\envs\houselossmodel\lib\site-packages\folium\features.py in __init__(self, geo_data, data, columns, key_on, bins, fill_color, nan_fill_color, fill_opacity, nan_fill_opacity, line_color, line_weight, line_opacity, name, legend_name, overlay, control, show, topojson, smooth_factor, highlight, **kwargs)
   1223             # We add the colorscale
   1224             nb_bins = len(bin_edges) - 1
-> 1225             color_range = color_brewer(fill_color, n=nb_bins)
   1226             self.color_scale = StepColormap(
   1227                 color_range,

~\Miniconda3\envs\houselossmodel\lib\site-packages\branca\utilities.py in color_brewer(color_code, n)
    150     if not explicit_scheme:
    151         # Check to make sure that it is not a qualitative scheme.
--> 152         if scheme_info[base_code] == 'Qualitative':
    153             matching_quals = []
    154             for key in schemes:

KeyError: 'RdYlBu'

The same error can be raised by doing

branca.utilities.color_brewer('RdYlBu', 30) #that colormap has only 11 colors

A workaround can be

branca.utilities.linear_gradient(branca.utilities.color_brewer('RdYlBu'), 30)

However there is no way that I can see to have color_brewer returning all available colors in that colormap unless you know how many there are. For example, branca.utilities.color_brewer('Accent') will return only the first 6 colors of Accent omitting the last two.
For this reason I reckon fixing this issue is better placed within branca more than folium

For the moment, and going forward I guess would be nice to be able to provide a list of hex colors of same length as bins when creating a Choropleth object