# help regarding extracting a smaller list from larger one

Gary Herron gherron at digipen.edu
Fri Sep 16 00:25:18 CEST 2011

```On 09/15/2011 11:55 AM, neeru K wrote:
> Dear Gary,
> thank you for the reply.
> I will be more specific and take the same example that you have given
> and tell you what is my problem -
> array([0.0, 1.3, 2.45, 3.87, 4.54, 5.11, 6.90, 7.78, 8.23, 9.01])
> from this array I want to a sub-list with lower and upper indexes that
> are not present in the above array for example - sub-list[3, 8]
> Is there a function for this?
> thank you
> niranjan

You say "index", but I think that is not what you mean.  An index is in
integer referring to an element's position in the array.   The "value"
at an index is what I believe you are referring to.

Nevertheless, I think list comprehension is what you want:
[ x  for x in A  if 3.0 <= x <= 8.0 ]
will extract all the values between 3 and 8 from the array A and create
a new list containing them.

If you want the new list to be a numpy array then
numpy.array([ x  for x in A  if 3.0 <= x <= 8.0 ])

>
>
> On Thu, Sep 15, 2011 at 10:54 PM, Gary Herron <gherron at digipen.edu
> <mailto:gherron at digipen.edu>> wrote:
>
>     On 09/15/2011 09:40 AM, neeru K wrote:
>
>         Dear Python Users,
>         I am trying to write a code for visualization (raster plots
>         and peri-event time histogram) of time series
>         electrophysiological data using numpy, scipy and matlplotlib
>         in python. I am importing the data into list using loadtext
>         command.
>         I was curious if anyone is aware of a function in numpy that
>         can *extract a smaller list containing numbers from a larger
>         list* given the upper and lower limit of the values between
>         which the smaller list lies.
>         Sincerely,
>         niranjan
>
>         --
>         Niranjan Kambi
>         Senior Research Fellow,
>         Neeraj Lab,
>         National Brain Research Centre,
>         Manesar, Gurgaon-122050
>         Haryana, INDIA
>         Ph:+919818654846 <tel:%2B919818654846>
>         website:-
>         http://www.nbrc.ac.in/faculty/neeraj/Lab_webpage/Niranjan_Kambi.html
>         email:- neuro.niru at nbrc.res.in <mailto:neuro.niru at nbrc.res.in>
>         <mailto:neuro.niru at nbrc.res.in
>         <mailto:neuro.niru at nbrc.res.in>>, neuroniru at gmail.com
>         <mailto:neuroniru at gmail.com> <mailto:neuroniru at gmail.com
>         <mailto:neuroniru at gmail.com>>
>
>     Do mean to extract a sub-list from a list based on lower and upper
>     indexes into the list?  Python has a standard notation for
>     indicating sub-lists, and numpy implements them:
>
>     >>> a = numpy.array(range(10))
>     >>> a
>     array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
>     >>> a[3:6]
>     array([3, 4, 5])
>
>     If you mean something else, please be more specific, and we'll try
>     again.
>
>     Gary Herron
>
>
>     --
>     Gary Herron, PhD.
>     Department of Computer Science
>     DigiPen Institute of Technology
>     (425) 895-4418 <tel:%28425%29%20895-4418>
>
>     --
>     http://mail.python.org/mailman/listinfo/python-list
>
>
>
>
>
>

--
Gary Herron, PhD.
Department of Computer Science
DigiPen Institute of Technology
(425) 895-4418

```