Problem with assignment. Python error or mine?
Tim Williams
tjandacw at cox.net
Fri Dec 22 08:52:10 EST 2017
On Friday, December 22, 2017 at 8:41:29 AM UTC-5, Tim Williams wrote:
> On Thursday, December 21, 2017 at 12:18:11 PM UTC-5, MarkA wrote:
> > On Thu, 21 Dec 2017 07:05:33 -0800, rafaeltfreire wrote:
> > From docs.python.org:
> >
> > 8.10. copy — Shallow and deep copy operations
> >
> > Source code: Lib/copy.py
> >
> > Assignment statements in Python do not copy objects, they create bindings
> > between a target and an object. For collections that are mutable or
> > contain mutable items, a copy is sometimes needed so one can change one
> > copy without changing the other. This module provides generic shallow and
> > deep copy operations (explained below)...
> >
> >
> > > Dear community, I am having the following problem when I am assigning
> > > the elements of a vector below a certain number to zero or any other
> > > value.
> > > I am creating a new variable but Python edits the root variable. Why?
> > >
> > > import numpy as np
> > >
> > > X=np.arange(1, 10000, 1) #root variable x1=X x1[x1<10000]=0
> > >
> > > print(X)
> > > Out[1]: array([ 0., 0., 0., ..., 0., 0., 0.])
> > >
> > > Why????????? It is supposed to be the original value Thank you for your
> > > time Rafael
> >
> >
> >
> > --
> > MarkA
> >
> > We hang petty theives, and appoint the great theives to public office
> > -- Aesop
>
> Shouldn't the OP just create a list for what he want's to do?
>
> X = list(np.arange(1, 10000, 1)) #root variable x1=X x1[x1<10000]=0
>
> Then I think his other statements would do what he expects, no?
Disregard what I just posted. I didn't think this through enough.
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