在mpl_toolkits.basemap.Basemap獲取工作的分散點的alpha值

Question

基於here的示例，我想繪製具有不同alpha值和不同顏色（我打算更新它們）的地圖上的點。然而，alpha值似乎沒有更新（它們似乎也被忽略了）。

首先，創建一個地圖，繪製三個點，按照這個例子：

from mpl_toolkits.basemap import Basemap 
import matplotlib.pyplot as plt 
import numpy as np 

fig, ax = plt.subplots() 

map = Basemap(projection='merc', lat_0 = 57, lon_0 = -135, 
    resolution = 'h', area_thresh = 0.1, 
    llcrnrlon=-136.25, llcrnrlat=56.0, 
    urcrnrlon=-134.25, urcrnrlat=57.75) 

map.drawcoastlines() 
map.drawcountries() 
map.fillcontinents(color = 'lightgray', zorder = 0) 
map.drawmapboundary() 

lons = [-135.3318, -134.8331, -134.6572] 
lats = [57.0799, 57.0894, 56.2399] 
x,y = map(lons, lats) 
pts = map.scatter(x, y, c ='r', marker = 'o', s = 80, alpha = 1.0) 

然後更新與新的RGBA值facecolors。

pts.set_facecolor([(0.7, 0.3, 0.3, 1.0), (1, 0.0, 1, 0.5), (1.0, 1.0, 0.2, 0.2)]) 
fig.canvas.draw() 

顏色更新但Alpha值不正確打印。我也嘗試過使用pts.set_alpha，但這不允許列表作爲參數。

Answer 1

所以，after posting this as an issue on github，看來如果你不擺在首位設置alpha值alpha值可以被更新。

from mpl_toolkits.basemap import Basemap 
import matplotlib.pyplot as plt 
import numpy as np 
import matplotlib 
matplotlib.interactive(True) 

fig, ax = plt.subplots() 

map = Basemap(projection='merc', lat_0 = 57, lon_0 = -135, 
    resolution = 'i', area_thresh = 0.1, 
    llcrnrlon=-136.25, llcrnrlat=56.0, 
    urcrnrlon=-134.25, urcrnrlat=57.75) 

map.drawcoastlines(zorder = 0) 
map.drawcountries(zorder = 0) 
map.fillcontinents(color = 'lightgray', zorder = 0) 
map.drawmapboundary(zorder = 0) 

lons = [-135.3318, -134.8331, -134.6572] 
lats = [57.0799, 57.0894, 56.2399] 
x,y = map(lons, lats) 
pts = map.scatter(x, y, c ='r', marker = 'o', s = 600) 

而且這些α值可以通過使用set_facecolor，像這樣被更新：

pts.set_facecolor([(0.7, 0.3, 0.3, 1.0), (1, 0.0, 1, 0.5), (1.0, 1.0, 0.2, 0.2)]) 
fig.canvas.draw() 

Answer 2

目前還不清楚您是否可以單獨爲每個點設置alpha值，但是如果使用多個plot命令，則它可以工作。

pts = bmap.scatter(x[0], y[0], c ='b', marker = 'o', s = 80, alpha = 0.7) 
pts = bmap.scatter(x[1], y[1], c ='g', marker = 'o', s = 80, alpha = 0.3) 
pts = bmap.scatter(x[2], y[2], c ='r', marker = 'o', s = 80, alpha = 0.5)