2

这是我试图可视化的数据示例

Prince Edward Island    2.333
Manitoba                2.529
Alberta                 2.6444
British Columbia        2.7902
Saskatchewan            2.9205
Ontario                 3.465
New Brunswick           3.63175
Newfoundland and Labrador   3.647
Nova Scotia             4.25333333333
Quebec                  4.82614285714
Nunavut                 NaN
Yukon                   NaN
Northwest Territories   NaN

我想通过根据与之关联的数字为每个省着色来可视化数据。当我这样做时，Nan 的颜色就像颜色图的最小值一样。有没有一种简单的方法可以将 Nan 映射到白色？

这是我的代码：

plt.figure(figsize=(15,15)) 


vmin, vmax = canada.Partying.min(), canada.Partying.max()

ax = canada.plot(column='Partying', cmap='viridis', vmin=vmin, vmax=vmax)

# add colorbar
fig = ax.get_figure()
cax = fig.add_axes([0.9, 0.1, 0.03, 0.8])
sm = plt.cm.ScalarMappable(cmap='viridis', norm=plt.Normalize(vmin=vmin, vmax=vmax))
# fake up the array of the scalar mappable. Urgh...
sm._A = []
fig.colorbar(sm, cax=cax)
plt.savefig('Canada.pdf')
4

2 回答 2

5

更新：geopandas解决您的问题的新功能：您现在可以使用：

ax = canada.plot(column='Partying', cmap='viridis', vmin=vmin, vmax=vmax,
     missing_kwds= dict(color = "lightgrey",) )

使所有缺失的数据区域变为浅灰色。

请参阅https://geopandas.readthedocs.io/en/latest/mapping.html （实际上，文档可能会说参数是missing_kwdsdict，但以上对我有用）

于 2020-01-12T21:15:25.740 回答
1

您可以合并两层：

## import statements
import geopandas as gpd
import numpy as np
import matplotlib.pyplot as plt

## load the Natural Earth data set 
world = gpd.read_file(gpd.datasets.get_path('naturalearth_lowres'))

## add a column with NaNs
## here we set all countries with a population > 10e7 to nan
world["pop_est_NAN"] = world.pop_est.apply(lambda x: x if x <10e7 else np.nan)

## first layer, all geometries included 
ax = world.plot(color="grey")

## second layer, NaN geometries excluded
## we skip the entries with NaNs by calling .dropna() on the dataframe
## we reference the first layer by ax=ax
## we specify the values we want to plot (column="pop_est")
world.dropna().plot(ax=ax, column="pop_est")

## add title
ax.set_title("Countries with a population > 10e7 (= missing values) \nare plotted in grey");

## save fig
plt.savefig("geopandas_nan_plotting.png", dpi=200)

geopandas_nan_plotting

查看geopandasmatplotlib文档，了解使用对象的替代方法。

于 2017-12-16T21:26:22.703 回答