[Numpy-discussion] Matlab page on scipy wiki

Travis Oliphant oliphant at ee.byu.edu
Fri Feb 10 14:29:05 CST 2006


Christopher Barker wrote:

> Colin J. Williams wrote:
>
>>> numpy.r_[1,0,range(1,5),0,1]
>>
>
>> This seems to be a neat idea but not in the usual Python style.
>
>
> Exactly. couldn't it at least get a meaningful, but short, name?

It is meaningful :-)  r_ means row concatenation...  (but, it has taken 
on more functionality than that).  What name do you suggest?

>
> And is there a way to use it to concatenate along other axis? I 
> couldn't see a way.

Yes, add a string at the end with the number of the axis you want to 
concatenate along.  But, you have to have that axis to start with or the 
result is no different.  The default is to concatenate along the last axis.

Thus  (the ndmin keyword forces the array to have a minimum number of 
dimensions --- prepended).

a = array([1,2,3],ndmin=2)  
b = array([1,2,3],ndmin=2)


c = r_[a,b,'0']

print c

[[1 2 3]
 [1 2 3]]


print r_[a,b,'1']

[[1 2 3 1 2 3]]


-Travis





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