How to combine characters of value in xarray dataset-CodePudding

I am extremely new to coding, so please correct me on anything I'm misunderstanding.

I need to find a way to combine the different characters in each value into a single string of characters. The data originally came from a netcdf file that I opened in xarray. The dtype was originally |S1, but I was able to convert it to a string using .astype(str) and then transposing, and this was the result.

ncases_OFCL: 2743, nchars_basin: 2

array([['a', 'l'],
       ['a', 'l'],
       ['a', 'l'],
       ...,
       ['e', 'p'],
       ['e', 'p'],
       ['e', 'p']], dtype='<U1')

Coordinates: (0)
Attributes:

long_name :
    OFCL basin
units :

Now that I've gotten to this point, is there a way to join the 'a' and 'l' and so on into just 'al'? Thank you for any help you can give!!

CodePudding user response：

Let me know if this works for you.

data  = np.array([['a', 'l'],
       ['a', 'l'],
       ['a', 'l'],
       ['e', 'p'],
       ['e', 'p'],
       ['e', 'p']])

data2 = []
for n in range(0,len(data)):
    data2.append(data[n,0]   data[n,1])

CodePudding user response：

The problem is the data is encoded as a fixed-width unicode array type, and you can't resize fixed-width character arrays.

Your data probably looks something like this:

In [16]: da = xr.DataArray(
    ...:     np.array([['a', 'l']] * 10   [['e', 'p']] * 10).astype('U'),
    ...:     dims=['ncases_OFCL', 'nchars_basin'],
    ...: )

In [17]: da
Out[17]:
<xarray.DataArray (ncases_OFCL: 20, nchars_basin: 2)>
array([['a', 'l'],
       ['a', 'l'],
       ['a', 'l'],
       ['a', 'l'],
       ['a', 'l'],
       ['a', 'l'],
       ['a', 'l'],
       ['a', 'l'],
       ['a', 'l'],
       ['a', 'l'],
       ['e', 'p'],
       ['e', 'p'],
       ['e', 'p'],
       ['e', 'p'],
       ['e', 'p'],
       ['e', 'p'],
       ['e', 'p'],
       ['e', 'p'],
       ['e', 'p'],
       ['e', 'p']], dtype='<U1')
Dimensions without coordinates: ncases_OFCL, nchars_basin

You can sum the characters along a dimension if you first convert the data to object type:

In [18]: da.astype('O').sum(dim='nchars_basin')
Out[18]:
<xarray.DataArray (ncases_OFCL: 20)>
array(['al', 'al', 'al', 'al', 'al', 'al', 'al', 'al', 'al', 'al', 'ep',
       'ep', 'ep', 'ep', 'ep', 'ep', 'ep', 'ep', 'ep', 'ep'], dtype=object)
Dimensions without coordinates: ncases_OFCL

If you'd like, you could convert back to fixed-width '<U2' type:

In [19]: da.astype('O').sum(dim='nchars_basin').astype('U')
Out[19]:
<xarray.DataArray (ncases_OFCL: 20)>
array(['al', 'al', 'al', 'al', 'al', 'al', 'al', 'al', 'al', 'al', 'ep',
       'ep', 'ep', 'ep', 'ep', 'ep', 'ep', 'ep', 'ep', 'ep'], dtype='<U2')
Dimensions without coordinates: ncases_OFCL