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

russel russel@appliedminds....
Fri Jan 27 11:12:30 CST 2012

```In [12]: a=np.arange(10)

In [13]: b=np.ones((10,))

In [14]: b[[3,4,7,8]] = np.nan

In [15]: a
Out[15]: array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

In [16]: b
Out[16]: array([  1.,   1.,   1.,  nan,  nan,   1.,   1.,  nan,  nan,   1.])

In [17]: nans = np.isnan(b)

In [18]: a[~nans]
Out[18]: array([0, 1, 2, 5, 6, 9])

In [19]: b[~nans]
Out[19]: array([ 1.,  1.,  1.,  1.,  1.,  1.])

On 01/27/2012 08:56 AM, Fabien Lafont wrote:
> thanks a lot. Is there a way to do so but acting on elements array? I
> explain you why. I have a vector with some 'nan' elements. I want to
> remove them and to know the position on the array to remove another
> element on another array but at the same 'place(position number)'
>
>
> 2012/1/27 Warren Weckesser<warren.weckesser@enthought.com>:
>>
>>
>> On Fri, Jan 27, 2012 at 10:49 AM, Fabien Lafont<lafont.fabien@gmail.com>
>> wrote:
>>>
>>> I have that [3,2,4,8,7,8,9] and I want [3,2,8,7,8] how can I do?  I've
>>> tried remove() but it works only on lists not on np.array.
>>
>>
>>
>> In [21]: a = array([3,2,4,8,7,8,9])
>>
>> In [22]: b = a[(a != 4)&  (a != 9)]
>>
>> In [23]: b
>> Out[23]: array([3, 2, 8, 7, 8])
>>
>>
>> Warren
>>
>>
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```