"Paul F. Dubois" wrote:
> -------------------------------------------
> If I have a character array t:
>
> >>> t = array(['abcd','aacd','ddfa','qqcd'])
> >>> print t
> [[a b c d]
> [a a c d]
> [d d f a]
> [q q c d]]
>
> I'm trying to find the row numbers that
> have a 'c' in the third column
> (and I'm trying to avoid a 'for' loop).
>
> What's the most efficient way to
> create an array that contains the indexes
> of the rows that match a particular pattern?
> (using masks?)
>
> The answer should be an array ([0,1,3])
> The obvious approach using equal doesn't seem to work. I'll forward your
> request.
It seems that equal() does not support the char type (anyone know why
not?):
>>> equal(t,'c')
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: function not supported for these types, and can't coerce to
supported types
The following is kind of an ugly kludge, but it does work:
>>> from Numeric import *
>>> t = array(['abcd','aacd','ddfa','qqcd'])
>>> t2 = t.astype(UnsignedInt8)
>>> nonzero(equal(t2,ord('c'))[:,2])
array([0, 1, 3])
-Chris
--
Christopher Barker,
Ph.D.
cb...@jp... --- --- ---
http://www.jps.net/cbarker -----@@ -----@@ -----@@
------@@@ ------@@@ ------@@@
Water Resources Engineering ------ @ ------ @ ------ @
Coastal and Fluvial Hydrodynamics ------- --------- --------
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