[SciPy-user] Question about trick index functions.
Travis Oliphant
oliphant.travis at ieee.org
Thu Jan 5 21:05:53 CST 2006
Hugo Gamboa wrote:
>So what is the difference between r_ and c_ ?
>
>
>
c_ is deprecated (it's there only for compatibility) :-)
For 1-d arrays there was never any difference.
For 2-d arrays c_ and r_ stacked along different dimensions.
Now, the r_ constructor can stack along any dimension by using a string
integer as the last element, but note this has the same limitation as
concatenate: the arrays stacked together must actually have the
dimension to stack along....
Compare the output of
a = arange(6).reshape(2,3)
r_[a,a]
with
r_[a,a,'-1']
c_[a,a] # not recommended for use anymore...
The real use of r_[] is to quickly concatenate arrays together to build
up complicated arrays. It was developed when I was using SciPy to teach
a signal processing course and the student lab-manuals had Matlab
exercises where they used matlab to build up compilcated arrays quickly
using bracket notation:
-Travis
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