numpy question (fairly basic, I think)

Gregory Ewing greg.ewing at canterbury.ac.nz
Sun Dec 14 17:26:19 EST 2014


Albert-Jan Roskam wrote:
> I was trying to change the one-dim array into a two-dim array so
> I could easily retrieve columns. I now use a pandas DataFrame to do that.

Numpy can do that, if I understand what you want correctly,
but it requires an unintuitive trick.

The trick is to index the array with the name of a field,
and *only* the name of the field. For example, the following
gives you a slice containing all the values from the 'v02'
fields of your data:

   array['v02']

Note: Indexing with a field name generally seems to follow
a different set of rules. Some things that you'd think would
work don't, e.g.

    array[:, 'v02']

fails with a rather confusing error message. Also,

    array[0, 'v02']

doesn't work either, and has to be written

    array[0]['v02']

instead.

-- 
Greg



More information about the Python-list mailing list