Sort a list with np.arrays python

Question

I want to sort a list with four numpy arrays.

import numpy as np 
import datetime

time_origin=[]

filelist=['3.csv','2.csv','1.csv','4.csv'] 

for i in np.arange(4):
    time_origin.append(np.loadtxt(
        filelist[i],delimiter=',',skiprows=1,usecols=(0,),unpack=True)) 

time_origin.sort()

However, it doesn't work.

The expected result:

for example:

a=[array[1,2,3,4],array[6,2],array[0,12,1,4,5]]

I want to sort a based on the length of each array

the expected result is:

a=[array[6,2],array[1,2,3,4],array[0,12,1,4,5]]

Padraic Cunningham · Accepted Answer · 2015-03-04 01:00:52Z

5

sort using len as the sort key:

 time_origin.sort(key=len)

Python sorts lists element by element, if all elements are the same the longer list will get sorted after but [1,2,3] will get sorted before [12] because 12 > 1.

edited Mar 4, 2015 at 1:00

answered Mar 4, 2015 at 0:55

Padraic Cunningham

181k30 gold badges264 silver badges327 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

ericmjl Over a year ago

Actually, in retrospect, a more relevant answer than my one.

ericmjl · Accepted Answer · 2015-03-04 00:55:19Z

3

Try using the built-in sorted function as such:

arrays = [np.array([1,2,3,4]), np.array([1,2]), np.array([1,2,3,4,5])
a = sorted(arrays, key=lambda x:len(x))

The core idea here is to use the lambda function.

answered Mar 4, 2015 at 0:55

ericmjl

14.9k13 gold badges57 silver badges83 bronze badges

Collectives™ on Stack Overflow

Sort a list with np.arrays python

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related