Anaconda读取nc数据出现问题？三维数组之间的加法运算。

LemonTree007

1. import netCDF4
   
2. import matplotlib.pyplot as plt
   
3. import numpy as np
   
4. from mpl_toolkits.basemap import Basemap
   
5. from eofs.standard import Eof
   
6. 
   
7. # read uwind
   
8. nc_obj = netCDF4.Dataset('D:\\wind_u_v\\ERA\\u.mon.mean.1958.2016.nc', 'r')
   
9. print(nc_obj.variables.keys())
   
10. lon = nc_obj.variables['longitude'][:]
    
11. lat = nc_obj.variables['latitude'][:]
    
12. time = nc_obj.variables['time'][:]
    
13. level = nc_obj.variables['level'][2]
    
14. u = nc_obj.variables['u'][:, :, :]
    
15. nc_obj.close()
    
16. 
    
17. # 截取研究区域和时段u风数据
    
18. lat_bounds = [-5, 40]
    
19. lon_bounds = [80, 130]
    
20. # latitude lower and upper index
    
21. lat_li = np.argmin(np.abs(lat - lat_bounds[0]))  # argmin(array):返回范围内最小值的位置索引号
    
22. lat_ui = np.argmin(np.abs(lat - lat_bounds[1]))
    
23. # longitude lower and upper index
    
24. lon_li = np.argmin(np.abs(lon - lon_bounds[0]))
    
25. lon_ui = np.argmin(np.abs(lon - lon_bounds[1]))
    
26. <b><font color="#008080">uSubset = u[:, lat_ui:lat_li, lon_li:lon_ui]</font></b>
    
27. 
    
28. # 处理缺测数据
    
29. u[u <= -32767] = np.nan
    
30. 
    
31. # 计算u风夏季平均值
    
32. u_JJA = np.zeros((59, lat_li-lat_ui, lon_ui-lon_li), dtype=np.float32)
    
33. for i in range(59):
    
34.      for j in range(5, 8):
    
35.      u_JJA[i, :, :] = u_JJA[i, :, :] + uSubset[12*i+j, :, :]
    
36. 
    
37.      u_JJA[i, :, :] = u_JJA[i, :, :]/3.

复制代码

Traceback (most recent call last):
  File "C:/Python_course/pygrads/test_eof.py", line 35, in <module>
    u_JJA[i, :, :] = u_JJA[i, :, :] + uSubset[12*i+j, :, :]
  File "C:\ProgramData\Anaconda3\lib\site-packages\numpy\ma\core.py", line 4077, in __radd__
    return add(other, self)
  File "C:\ProgramData\Anaconda3\lib\site-packages\numpy\ma\core.py", line 1019, in __call__
    result = self.f(da, db, *args, **kwargs)
ValueError: operands could not be broadcast together with shapes (18,20) (3,20,144)


大概明白是因为两个数组之间的维数不同无法进行运算，但感觉维数都是三维，一样的呀

LemonTree007

找到问题所在了，代码13，14行，改成
level = nc_obj.variables['level']
u = nc_obj.variables['u'][:,2, :, :]
因为nc文件中的变量u是四维的，只能通过这样的方式固定level