to merge lists in python

Question

I have the following python code:

import subprocess

def disk():
for i in ('/tmp' , '/usr/mware' , '/var' , '/var/mware'):
    df1 = subprocess.Popen(['df','-h', i], stdout=subprocess.PIPE).communicate()[0].split()
    df1.remove("on")
    print df1

disk()

I am getting the following output:

['Filesystem', 'Size', 'Used', 'Avail', 'Use%', 'Mounted', '/dev/mapper/rootvg-tmplv', '2.0G', '39M', '2.0G', '2%', '/tmp']
['Filesystem', 'Size', 'Used', 'Avail', 'Use%', 'Mounted', '/dev/mapper/appvg-usrmwarelv', '20G', '33M', '20G', '1%', '/usr/mware']
['Filesystem', 'Size', 'Used', 'Avail', 'Use%', 'Mounted', '/dev/mapper/rootvg-varlv', '10G', '3.8G', '6.3G', '38%', '/var']
['Filesystem', 'Size', 'Used', 'Avail', 'Use%', 'Mounted', '/dev/mapper/appvg-varmwarelv', '20G', '33M', '20G', '1%', '/var/mware']

I want to merge these lists and remove duplicates.

And what is an expecting result? You want merge lists or their elements? — Dmitry
– Dmitry, Commented Jun 9, 2017 at 10:04

frhyme · Accepted Answer · 2017-06-09 10:09:19Z

1

merging lists is so simple.

a= ['Filesystem', 'Size', 'Used', 'Avail', 'Use%', 'Mounted', '/dev/mapper/rootvg-tmplv', '2.0G', '39M', '2.0G', '2%', '/tmp']
b= ['Filesystem', 'Size', 'Used', 'Avail', 'Use%', 'Mounted', '/dev/mapper/appvg-usrmwarelv', '20G', '33M', '20G', '1%', '/usr/mware']
c= ['Filesystem', 'Size', 'Used', 'Avail', 'Use%', 'Mounted', '/dev/mapper/rootvg-varlv', '10G', '3.8G', '6.3G', '38%', '/var']
d = ['Filesystem', 'Size', 'Used', 'Avail', 'Use%', 'Mounted', '/dev/mapper/appvg-varmwarelv', '20G', '33M', '20G', '1%', '/var/mware']
remove_duplicates = list(set(a+b+c+d))

edited Jun 9, 2017 at 10:09

answered Jun 9, 2017 at 10:06

frhyme

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1 Comment

Right leg Over a year ago

+1, but I'm curious about the comparison between merging the lists first and then setting them, and setting the lists first and then taking their union...

Akshay Kandul · Accepted Answer · 2017-06-09 10:27:25Z

1

import subprocess

def disk():
    df_set = set()
    for i in ('/tmp', '/usr/mware', '/var', '/var/mware'):
        df1 = subprocess.Popen(['df','-h', i], stdout=subprocess.PIPE).communicate()[0].split()
        df1.remove("on")
        df_set = df_set.union(set(df1))
    print(list(df_set))
disk()

Above code will merge your list and remove duplicates from it.

answered Jun 9, 2017 at 10:27

Akshay Kandul

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Comments

Tbaki · Accepted Answer · 2017-06-09 10:07:28Z

0

You can concatenate and use set :

def disk():
    df = []
    for i in ('/tmp' , '/usr/mware' , '/var' , '/var/mware'):
        df1 = subprocess.Popen(['df','-h', i], stdout=subprocess.PIPE).communicate()[0].split()
        df1.remove("on")
        df = df + df1
    return set(df)

answered Jun 9, 2017 at 10:07

Tbaki

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Comments

Sachin · Accepted Answer · 2017-06-09 10:13:44Z

import subprocess

# prepare a list of columns in the beginning
df_out = [['Filesystem', 'Size', 'Used', 'Avail', 'Use%', 'Mounted']]

def disk():
    for i in ('/tmp' , '/usr/mware' , '/var' , '/var/mware'):
        df1 = subprocess.Popen(['df','-h', i], 
                    stdout=subprocess.PIPE).communicate()[0].split()
        df1.remove("on")

        # append the remaining columns in the list 'df1'
        df_out.append(df1[6:])

disk()

# print the final output
print df_out

This will give you the output as -

[['Filesystem', 'Size', 'Used', 'Avail', 'Use%', 'Mounted'],
 ['/dev/mapper/rootvg-tmplv', '2.0G', '39M', '2.0G', '2%', '/tmp'],
 ['/dev/mapper/appvg-usrmwarelv', '20G', '33M', '20G', '1%', '/usr/mware'],
 ['/dev/mapper/rootvg-varlv', '10G', '3.8G', '6.3G', '38%', '/var'],
 ['/dev/mapper/appvg-varmwarelv', '20G', '33M', '20G', '1%', '/var/mware']]

MSeifert · Accepted Answer · 2017-06-09 10:17:20Z

0

You could use the set.union method:

list(set(df1).union(df2, df3, df4))  # assuming the invidual lists are called df1, df2, ...

a set is an unordered collection of unique objects. You'll lose the duplicates but also lose your order. In case you want it ordered and without duplicates you could use OrderedDict:

from collections import OrderedDict
from itertools import chain

list(OrderedDict.fromkeys(chain(a, b, c, d)))

answered Jun 9, 2017 at 10:17

MSeifert

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Comments

Błotosmętek · Accepted Answer · 2017-06-09 10:08:43Z

-1

Why do you spawn separate processes for every filesystem to check, while df is able to check all of them in one run?

df1 = subprocess.Popen(['df','-h', '/tmp' , '/usr/mware' , '/var' , '/var/mware'], stdout=subprocess.PIPE).communicate()[0].split()

answered Jun 9, 2017 at 10:08

Błotosmętek

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2 Comments

Right leg Over a year ago

Although that's a good remark, this is not the point of the question. You should post this as a comment instead.

user3640472 Over a year ago

Thanks, It worked for me, i edited the code like:

import subprocess  def disk():     df = []     for i in ('/tmp' , '/usr/mware' , '/var' , '/var/mware'):         df1 = subprocess.Popen(['df','-h', '/tmp' , '/usr/mware' , '/var' , '/var/mware'], stdout=subprocess.PIPE).communicate()[0].split()     df1.remove("on")     print df1   disk()

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