[Tutor] Assessing local variable outside function

[Peter Otten]

nils wagenaar wrote:

> Hello,
> 
> 
> Could i use a variable defined in a function in another function?
> 
> I have now:
> 
> 
> 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

It doesn't help that you put all return statements on the same line, only 
the first

       return data

is executed; the other two are unreachable code.

> So, i want to use latselect and lonselect in a different function where i
> interpolate for the subsetted area.

In Python while you can return only one value you can easily combine 
multiple values into one tuple. Instead of

>      return data; return latselect; return lonselect

write

       return data, latselect, lonselect

When you call the function you can either access the parts of the tuple with 
their respective index

result = DatasetToSubset(...)

lat = result[1]

or use a language feature called "unpacking" to break the tuple into the 
individual values:

data, lat, lon = DatasetToSubset(...)