我如何评估一个局部变量函数？

Question

在这部分代码中，我定义了一个函数来对感兴趣的区域进行子集。但是，我想在后面的另一个函数中使用变量latselect和lonselect。所以，我有：

def DatasetToSubset(file, LatUpbound, LatLowBound, LonUpBound, LonLowBound): 
    nc=netCDF4.Dataset(file) 
    lats=nc.variables['lat'][:]; lons=nc.variables['lon'][:] 
    latselect=np.logical_and(lats > LatLowBound, lats < LatUpBound)  
    lonselect=np.logical_and(lon > LonLowBound, lon < LonUpBound) 
    data=nc.variables['Runoff'][1000, latselect, lonselect] 
    return data; return latselect; return lonselect 

Answer 1

一旦功能达到return声明，它返回值，并立即终止，这意味着随后的两个语句将不会执行。您可以返回三个值的元组，这样

def DatasetToSubset(file, LatUpbound, LatLowBound, LonUpBound, LonLowBound): 
    nc=netCDF4.Dataset(file) 
    lats=nc.variables['lat'][:]; lons=nc.variables['lon'][:] 
    latselect=np.logical_and(lats > LatLowBound, lats < LatUpBound)  
    lonselect=np.logical_and(lon > LonLowBound, lon < LonUpBound) 
    data=nc.variables['Runoff'][1000, latselect, lonselect] 
    return (data, latselect, lonselect) 

，当你调用这个函数，你可以解开三个值这样

(a, b, c) = DatasetToSubset(...) 

a将持有的data值，blatselect和c即lonselect。