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
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