如何显示底图的颜色栏 [英] How to display a colorbar for a Basemap

问题描述

我有一个 shapefile 和类似的系列:

I have a shapefile and a series like this:

UF
Acre                     261
Alagoas                  657
Amazonas                 793
Amapá                    162
Bahia                   1867
Ceará                   5657
Distrito Federal         430
Espírito Santo          1734
Goiás                   4110
Maranhão                1421
Minas Gerais           11812
Mato Grosso do Sul      1006
Mato Grosso             1391
Pará                    1889
Paraíba                 1575
Pernambuco              4019
Piauí                   1665
Paraná                  3745
Rio de Janeiro          1613
Rio Grande do Norte     1998
Rondônia                3102
Roraima                  237
Rio Grande do Sul       5643
Santa Catarina          5372
Sergipe                  413
São Paulo               8237
Tocantins                771
Name: 0, dtype: int64

其中UF是shapefile中显示的状态名称，系列值是我要用于生成颜色以填充底图的值.这是我到目前为止所得到的:

Where UF is the state name as presented in the shapefile and the series values are the values that I want to use to generate colors to fill a basemap. This is what I got so far:

import matplotlib.pyplot as plt
from matplotlib.patches import Polygon
from mpl_toolkits.basemap import Basemap
import matplotlib.cm as cm
import matplotlib as mpl
from matplotlib.collections import PatchCollection


def make_map(ax):
    m = Basemap(projection='merc', llcrnrlat=-35, urcrnrlat=7,
                llcrnrlon=-77, urcrnrlon=-32, resolution='i', ax=ax)
    m.fillcontinents()
    return m

def drawstates(fig, ax, data, shapefile='../BRA_adm_shp/BRA_adm1'):
    shp = m.readshapefile(shapefile, 'states', drawbounds=False)

    norm = mpl.colors.Normalize(vmin=data.min(), vmax=data.max())
    cmap = cm.hot
    sm = cm.ScalarMappable(norm=norm, cmap=cmap)
    colors = []
    patches = []

    for nshape, seg in enumerate(m.states):
        uf = m.states_info[nshape]['NAME_1']
        color  = sm.to_rgba(data[uf])
        poly = Polygon(seg, facecolor=color, edgecolor='white')
        ax.add_patch(poly)
        patches.append(poly)
        colors.append(color)

    p = PatchCollection(patches, cmap=cmap)
    p.set_array(np.array(colors))
    cb = fig.colorbar(p, ax=ax, orientation='horizontal')

fig, axes = plt.subplots(1, 2, figsize=(20, 10))
m = make_map(axes[0])
drawstates(fig, m.ax, m1)

哪个会导致:

我不确定这是否是正确的方法，但是我想知道如何保留输入值的比例，即不缩放颜色条在0和1之间，以及如何防止这么大的距离在地图及其颜色栏之间.

I'm not sure if this is the correct way of doing it, but I wonder how to preserve the scale of the input values, i.e., of not scaling the colorbar between 0 and 1, and how to prevent this big distance between the map and its colorbar.

推荐答案

根据ScalaMappable sm对多边形进行着色.因此，此ScalarMappable是您要提供给颜色图的参数的那个

The polygons are colorized according to the ScalaMappable sm. Hence this ScalarMappable is the one you want to give as argument to the colormap

sm = cm.ScalarMappable(norm=norm, cmap=cmap)
sm.set_array([]) # can be an empty list, only needed for matplotlib < 3.1
# ...
cb = fig.colorbar(sm, ax=ax, orientation='horizontal')

可以使用pad参数设置轴和颜色栏之间的填充.默认值应为pad=0.15，您将需要自己找到一个不错的值.

The padding between axes and colorbar can be set with the pad argument. The default should be pad=0.15 and you will need to find a good value yourself.

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