Plotly Choropleth地图：自定义颜色字典无法正确映射颜色

嘿，我看你遇到的问题很典型——自定义颜色没生效反而出现了奇怪的默认色，核心原因是你对Plotly的color_discrete_map参数用法理解错啦！

咱们先拆解下原代码里的问题：
你先给州名映射了颜色，生成了color列（值是'green'/'red'/'gray'），然后在px.choropleth里指定color='color'，这时候Plotly是把color列里的这三个字符串当成类别来处理的。但你传的color_discrete_map还是原来的州名-颜色字典，Plotly找不到对应'green'/'red'/'gray'这些类别的颜色映射，就自动用了默认的离散色板，所以才出现了粉色、浅蓝这些奇怪的颜色。

给你两种解决思路，选哪种都行：

思路1：修正color_discrete_map的映射关系 #

既然你已经生成了color列，那color_discrete_map需要对应color列里的三个类别，直接把每个颜色字符串映射到自身就行：

import geopandas as gpd
import plotly.express as px

# Path to the shapefile of Brazilian states
shapefile_path = 'brasil_estados.json'

# Load the shapefile using geopandas
brasil_mapa = gpd.read_file(shapefile_path, encoding='utf-8')

# Custom color dictionary (red and green)
color_dict = {
    'Minas Gerais': 'green',
    'Tocantins': 'red',
    'Amapá': 'red',
    'Roraima': 'red',
    'Goiás': 'red',
    'Distrito Federal': 'red'
}

# Map colors according to the dictionary
# If the state is not in the dictionary, it will be colored 'gray'
brasil_mapa['color'] = brasil_mapa['name'].map(color_dict).fillna('gray')

# 修正color_discrete_map：对应color列的三个类别
color_discrete_map = {
    'green': 'green',
    'red': 'red',
    'gray': 'gray'
}

# Plot the map using Plotly
fig = px.choropleth(
    brasil_mapa,
    geojson=brasil_mapa.geometry.__geo_interface__,
    locations=brasil_mapa.index,
    color='color',
    color_discrete_map=color_discrete_map,  # 用修正后的映射
    labels={'color': 'State'},
    scope='south america',
    title='Map of Brazilian States with Custom Colors',
    width=1200,
    height=800
)

# Adjusting map visualization
fig.update_geos(fitbounds="locations", visible=False)

# Show the plot
fig.show()

思路2：直接用州名作为颜色类别（更简洁） #

其实不需要额外生成color列，直接把州名作为颜色分类，然后在color_discrete_map里把你指定的州映射到对应颜色，再用'default'参数设置未指定州的默认灰色，这样代码更精简：

import geopandas as gpd
import plotly.express as px

# Path to the shapefile of Brazilian states
shapefile_path = 'brasil_estados.json'

# Load the shapefile using geopandas
brasil_mapa = gpd.read_file(shapefile_path, encoding='utf-8')

# Custom color dictionary (red and green)
color_dict = {
    'Minas Gerais': 'green',
    'Tocantins': 'red',
    'Amapá': 'red',
    'Roraima': 'red',
    'Goiás': 'red',
    'Distrito Federal': 'red'
}

# Plot the map using Plotly
fig = px.choropleth(
    brasil_mapa,
    geojson=brasil_mapa.geometry.__geo_interface__,
    locations=brasil_mapa.index,
    color='name',  # 直接用州名作为颜色分类依据
    # 合并自定义颜色和默认灰色
    color_discrete_map={**color_dict, 'default': 'gray'},
    labels={'name': 'State'},
    scope='south america',
    title='Map of Brazilian States with Custom Colors',
    width=1200,
    height=800
)

# Adjusting map visualization
fig.update_geos(fitbounds="locations", visible=False)

# Show the plot
fig.show()

这两种方法都能让你指定的州显示红/绿色，其他州显示灰色，不会再出现奇怪的默认色啦！

备注：内容来源于stack exchange，提问作者Mário Henrique