[SciPy-User] [scipy-user] How to remove a value from an np array?

Fabien Lafont lafont.fabien at gmail.com
Fri Jan 27 13:28:38 EST 2012


Thx,

I have another. First I expose my problem I have datas like that. Is
it possible to create an array with two columns and then do something
to erase the entire line(both time and points) where nan appears?


X(Time)     Points
1                  5
2                 nan
3                  3
4                  4
5                 nan
...


2012/1/27 David Warde-Farley <wardefar at iro.umontreal.ca>:
> On Fri, Jan 27, 2012 at 06:48:45PM +0100, Fabien Lafont wrote:
>> And how can I remove a specific element designated by its position
>> numer? like remove(a[8]) for exemple.
>
> This is generally not something you want to be doing with NumPy arrays. NumPy
> arrays represent fixed blocks of memory, removing an element means
> reallocating the array and copying values before and after position 8 is the
> only way.
>
> If a is one-dimensional, then np.concatenate(a[:8], a[9:]) will do the job,
> but if you are going to be frequently performing this kind of operation you
> will get better performance out of a plain Python list.
>
> David
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