cartopy学习笔记-练习1

JOJOweibo

Task:1)绘等值线（以SLP为例）；2）画出两幅子图

仍需改进的地方：colorbar的大小和方向需要调整；地图调整为函数形式；地图调整为区域地图；叠加等值线（希望有高手回帖指点，谢谢）

参考资料：1）matoplot画等值线 https://matplotlib.org/gallery/images_contours_and_fields/pcolormesh_levels.html
2）cartopy入门 http://bbs.06climate.com/forum.p ... 3601&extra=page%3D1
3）官网例子 http://scitools.org.uk/cartopy/docs/latest/matplotlib/advanced_plotting.html
4）axes与subplot的区别 https://www.zhihu.com/question/51745620

1. import matplotlib.pyplot as plt
   
2. import cartopy.crs as ccrs
   
3. import cartopy.feature as cfeature
   
4. from cartopy.mpl.ticker import LongitudeFormatter, LatitudeFormatter
   
5. from netCDF4 import Dataset
   
6. from matplotlib.ticker import MaxNLocator
   
7. from matplotlib.colors import BoundaryNorm
   
8. #==============================================================================
   
9. #读入数据
   
10. f = Dataset('...slp.nc')
    
11. #print(f)
    
12. 
    
13. slp1    = f.variables['slp1'][0,:,:]
    
14. slp2    = f.variables['slp2'][0,:,:]
    
15. lat          = f.variables['lat'][:]
    
16. lon          = f.variables['lon'][:]
    
17. 
    
18. #==============================================================================
    
19. #创建图纸，子图
    
20. fig = plt.figure(figsize=(8, 10))
    
21. #set colormap
    
22. levels = MaxNLocator(nbins=16).tick_values(-2.0, 2.0) #设置等值线值
    
23. cmap   = plt.get_cmap('bwr')  #选择coloarmap
    
24. norm   = BoundaryNorm(levels, ncolors=cmap.N, clip=True) #标准化coloarmap
    
25. #画第一个子图
    
26. # Label axes of a Plate Carree projection with a central longitude of 180:
    
27. ax1 = plt.subplot(211, projection=ccrs.PlateCarree(central_longitude=180))
    
28. ax1.set_global() #使得轴域（Axes即两条坐标轴围城的区域）适应地图的大小
    
29. ax1.coastlines() #画出海岸线
    
30. 
    
31. ax1.set_xticks([0, 60, 120, 180, 240, 300, 360], crs=ccrs.PlateCarree()) #标注坐标轴
    
32. ax1.set_yticks([-90, -60, -30, 0, 30, 60, 90], crs=ccrs.PlateCarree())
    
33. lon_formatter = LongitudeFormatter(zero_direction_label=True) #zero_direction_label=False 用来设置经度的0度加不加E和W
    
34. lat_formatter = LatitudeFormatter()
    
35. ax1.xaxis.set_major_formatter(lon_formatter)
    
36. ax1.yaxis.set_major_formatter(lat_formatter) #标注坐标轴
    
37. 
    
38. #画等值线
    
39. plt.contourf(lon,lat,slp1,15, levels=levels, cmap=cmap,transform=ccrs.PlateCarree())
    
40. 
    
41. plt.colorbar()
    
42. #==============================================================================
    
43. #画第二个子图
    
44. # Label axes of a Mercator projection without degree symbols in the labels
    
45. # and formatting labels to include 1 decimal place:
    
46. ax2 = plt.subplot(212, projection=ccrs.PlateCarree(central_longitude=180))
    
47. ax2.set_global()
    
48. ax2.coastlines()
    
49. ax2.set_xticks([-180, -120, -60, 0, 60, 120, 180], crs=ccrs.PlateCarree())
    
50. ax2.set_yticks([-90, -60, -30, 0, 30, 60, 90], crs=ccrs.PlateCarree())
    
51. lon_formatter = LongitudeFormatter(zero_direction_label=True) #zero_direction_label=False 用来设置经度的0度加不加E和W
    
52. lat_formatter = LatitudeFormatter()
    
53. ax2.xaxis.set_major_formatter(lon_formatter)
    
54. ax2.yaxis.set_major_formatter(lat_formatter)
    
55. 
    
56. #画等值线
    
57. plt.contourf(lon,lat,slp2,15, levels=levels, cmap=cmap,transform=ccrs.PlateCarree())
    
58. plt.colorbar(ax=ax2)
    
59. fig.tight_layout()
    
60. plt.savefig("./fig/06carotpy.contourf.png")

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weinihou

感谢分享~

临过年都这么努力，一定进步大大滴有~~
{:5_235:}

zyr

楼主好棒！

zhangqqqf

很不错，标记一下留着以后用

天狼007

楼主 你太厉害了

zyr

楼主好强大！向你学习！

geotail

不错不错！！！

junyang517

Very Good ~ & ~ Thanks~

hector

向楼主学习一下ヾ()~

Paranoia

楼主好棒！