Hi, I am trying to make a choropleth map from a shapefile using pygmt. I followed one answer on how to plot polygons using pygmt from geodataframe, but when I specify color=gdf.aal_com to color each polygon by column vasues I get an error:
GMTInvalidInput: Can’t use arrays for color if data is matrix or file.
import geopandas as gpd
import pygmt
import os
#%%
gdf = gpd.read_file('../Albania_loss.shp')
gdf.head()
hex_id
pop
square_pop
NAME_0
aal_com
geometry
0
7310
9749.987529
98.742025
Albania
41208.410919
POLYGON ((19.58093 40.88737, 19.52319 40.88737…
1
8112
476.375406
21.826026
Albania
3317.674009
POLYGON ((20.01394 40.13737, 19.95620 40.13737…
# collect extent region
bound = gdf.total_bounds
region = [bound[0], bound[2], bound[1], bound[3]]
# write to (tmp) file
# !geopandas (fiona) is not able to overwrite this format
filename = '../albania.gmt'
gdf.to_file(filename, driver='OGR_GMT')
# plot
fig = pygmt.Figure()
fig.basemap(region=region, projection="M20c", frame=True)
fig.plot(data='albania.gmt',color=gdf.aal_com)
fig.show(method='external')
Is there another way to achieve like the following in pygmt?
Choropleth maps are not easy to do in GMT. I’m able to do them from Julia but I use the -Z option and some helping functions to set the zvals. Not very helpful I know, sorry.
fig = pygmt.Figure()
fig.basemap(region=region, projection="M20c", frame=True)
pygmt.makecpt(cmap="batlow", series=[0, 50000, 100], reverse=True, continuous=True)
fig.plot(
data="albania.gmt", # input OGR data file
pen="0.05p,yellow,-", # set outline colour
cmap=True, # use colormap from makecpt
color="+z", # color based on the Z column
close=True, # force close polygons
a="Z=aal_com", # set aspatial column to 'aal_com'
)
fig.colorbar(position="jMR+jMR+w5c+o0.5c/1c+e")
fig.show()
