numpy.where

[Carl Banks]

On Apr 9, 1:33 am, Neil Crighton <neilcrigh... at gmail.com> wrote:
> heidi taynton <heidihannah <at> mac.com> writes:
>
>
>
> > Hi,  
>
> > I'm fairly new to programming and am having a probably cutting my arrays.  I
>
> have two different 1d arrays, one> of time, and the second energy.    I want to cut both arrays of time
>
> min<=time<=max  .   I've created a 2d array> with [time,energy] and I believe numpy.where is what I am looking for, but
>
> haven't been able to get the
>
> > conditions in right for it to work.  
>
> I'm not sure exactly what you're trying to do, but maybe you want a boolean
> array to select the right elements? So if time and energy are 1-d numpy arrays
> of the same length:
>
> >>> condition = (min_time <= time) & (time <= max_time)
> >>> new_time = time[condition]
> >>> new_energy = energy[condition]

Won't work: condition is an array of ones and zeros, but you need to
index the arrays with indices.  So, add a call to nonzero to get the
indices of the elements.

elements = nonzero(logical_and(min_time<=time,max_time>=time))

new_time = time[elements]
new_energy = energy[elements]


Carl Banks