Cartopy 和 PIL 的问题

Question

我在新系统上安装了 Anaconda Spyder，我收到以下错误消息：

C:\ProgramData\Anaconda3\lib\site-packages\PIL\Image.py:973: 用户警告：透明度以字节表示的调色板图像应转换为 RGBA 图像 警告.warn(

下面是我正在使用的代码。

Python 3.8.8（默认，2021 年 4 月 13 日，15:08:03）[MSC v.1916 64 位 (AMD64)] 输入“copyright”、“credits”或“license”了解更多信息。

IPython 7.22.0 -- 增强的交互式 Python。

正在重启内核...

import matplotlib.pyplot as plt
import cartopy.crs as ccrs
import cartopy.feature as cfeature
import cartopy 
import cartopy.io.img_tiles as cimgt
from cartopy.mpl.gridliner import LONGITUDE_FORMATTER, LATITUDE_FORMATTER

cartopy.config['pre_existing_data_dir']='C:/Users/***<USER>***/.local/share/cartopy'

mapSize = '10m'
zoom = 8
rivers = cfeature.NaturalEarthFeature('physical', 'rivers_lake_centerlines', mapSize)
states_provinces = cfeature.NaturalEarthFeature(category='physical', 
name='admin_1_states_provinces_lines', scale=mapSize, facecolor='none')
request = cimgt.OSM()
stamen_terrain = cimgt.Stamen('terrain-background')

longMax = 126.38765
longMin = -132.80147
latMax = 54.03728
latMin = 34.90657

# Create a Stamen terrain background instance.
stamen_terrain = cimgt.Stamen('terrain-background')
fig = plt.figure(figsize=(90, 50))
ax = fig.add_subplot(1, 1, 1, projection=request.crs)

gl = ax.gridlines(crs=ccrs.PlateCarree(), draw_labels=True, linewidth=2, color='gray', 
alpha=0.5, linestyle='--')
gl.top_labels = gl.right_labels = False
gl.xformatter = LONGITUDE_FORMATTER
gl.yformatter = LATITUDE_FORMATTER
gl.xlabel_style = {'size': 22, 'color': 'black', 'weight': 'bold'}
gl.ylabel_style = {'size': 22, 'color': 'black', 'weight': 'bold'}

# Limit the extent of the map to a small longitude/latitude range.
extent = [longMax, longMin, latMax, latMin]
ax.set_extent(extent, crs=ccrs.PlateCarree())

# Set the Stamen data zoom level
ax.add_image(stamen_terrain, zoom)

此错误/警告并不总是发生，但当它发生时，程序似乎冻结并且没有其他任何事情发生。即使我停止当前命令，也不会发生任何事情。我唯一能做的就是重启内核。

非常感谢任何帮助解决此问题。

Answer 1

鉴于地图的面积，缩放级别似乎太高了。将缩放级别更改为 7 解决了该问题。

我还注意到，如果地图区域缩小，则缩放级别 8 有效。

为解决此问题，地图大小和缩放级别基于地图区域。代码如下：

import matplotlib.pyplot as plt
import cartopy.crs as ccrs
import cartopy.feature as cfeature
import cartopy 
import cartopy.io.img_tiles as cimgt
from cartopy.mpl.gridliner import LONGITUDE_FORMATTER, LATITUDE_FORMATTER
import numpy as np
from pyproj import Proj

cartopy.config['pre_existing_data_dir']='C:/Users/Examiner/.local/share/cartopy'

####################################################################
# Calculate Map Area
####################################################################
def areaCalc(longMax, longMin, latMax, latMin):
    co = {"type": "Polygon", "coordinates": [[(longMax,latMax), 
        (longMax,latMin), (longMin,latMin), (longMin,latMax), 
        (longMax,latMax)]]}
    lon, lat = zip(*co['coordinates'][0])
    pa = Proj("+proj=aea +lat_1="+str(latMin)+" +lat_2=" + str(latMax) + " 
       +lat_0=" + str((latMax+latMin)/2) + " +lon_0=" + 
       str((longMax+longMin)/2))
    x, y = pa(lon, lat)
    area = np.abs(0.5*np.sum(y[:-1]*np.diff(x) - x[:-1]*np.diff(y)))
    return(area)
####################################################################

longMax = 126.38765
longMin = -132.80147
latMax = 54.03728
latMin = 34.90657

area = areaCalc(longMax, longMin, latMax, latMin)
if area <= 210000000000:
    mapSize = '10m'
    zoom = 8
elif area > 210000000000 and area <= 14500000000000:
    mapSize = '50m'
    zoom = 6  
else:
    mapSize = '110m'
    zoom = 4

rivers = cfeature.NaturalEarthFeature('physical', 'rivers_lake_centerlines', 
    mapSize)
states_provinces = cfeature.NaturalEarthFeature(category='physical', 
    name='admin_1_states_provinces_lines', scale=mapSize, facecolor='none')
request = cimgt.OSM()
stamen_terrain = cimgt.Stamen('terrain-background')

# Create a Stamen terrain background instance.
stamen_terrain = cimgt.Stamen('terrain-background')
fig = plt.figure(figsize=(90, 50))
ax = fig.add_subplot(1, 1, 1, projection=request.crs)

gl = ax.gridlines(crs=ccrs.PlateCarree(), draw_labels=True, linewidth=2, 
   color='gray', alpha=0.5, linestyle='--')
gl.top_labels = gl.right_labels = False
gl.xformatter = LONGITUDE_FORMATTER
gl.yformatter = LATITUDE_FORMATTER
gl.xlabel_style = {'size': 22, 'color': 'black', 'weight': 'bold'}
gl.ylabel_style = {'size': 22, 'color': 'black', 'weight': 'bold'}

# Limit the extent of the map to a small longitude/latitude range.
extent = [longMax, longMin, latMax, latMin]
ax.set_extent(extent, crs=ccrs.PlateCarree())

# Set the Stamen data zoom level
ax.add_image(stamen_terrain, zoom)