[Numpy-discussion] Deleting a row from a matrix
Travis Oliphant
oliphant.travis at ieee.org
Fri Aug 25 10:01:58 CDT 2006
Travis Oliphant wrote:
>> Now of course: I often needed to "insert" a column, row or section, ... ?
>> I made a quick and dirty implementation for that myself:
>> def insert(arr, i, entry, axis=0):
>> """returns new array with new element inserted at index i along axis
>> if arr.ndim>1 and if entry is scalar it gets filled in (ref. broadcasting)
>>
>> note: (original) arr does not get affected
>> """
>> if i > arr.shape[axis]:
>> raise IndexError, "index i larger than arr size"
>> shape = list(arr.shape)
>> shape[axis] += 1
>> a= N.empty(dtype=arr.dtype, shape=shape)
>> aa=N.transpose(a, [axis]+range(axis)+range(axis+1,a.ndim))
>> aarr=N.transpose(arr, [axis]+range(axis)+range(axis+1,arr.ndim))
>> aa[:i] = aarr[:i]
>> aa[i+1:] = aarr[i:]
>> aa[i] = entry
>> return a
>>
>>
>
> Sure, it makes sense to parallel the delete function.
>
Although there is already and insert function present in numpy....
-Travis
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