how do I match an element with a list?

Question

I am trying to match id with id_list using a one-liner,following doesnt seem to work,how do I fix it?

id  = 77bb1b03
id_list = ['List of devices attached ', '572ea01e\tdevice', '77bb1b03\tdevice', '']
if id in id_list:
     print "id present"
else:
     print "id not present"

score 2 · Accepted Answer · answered Jul 01 '16 at 06:08

2

You aren't matching on equality but on a substring of the values in the list, assuming you just want to match the start:
Note: assuming id is actually a string because it isn't a valid literal.

id  = '77bb1b03'
id_list = ['List of devices attached ', '572ea01e\tdevice', '77bb1b03\tdevice', '']
if any(i.startswith(id) for i in id_list):
    print "id present"
else:
    print "id not present"

answered Jul 01 '16 at 06:08

AChampion

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2

Or ``any(id in i for i in id_list)`` if the id can also appear in the middle of one of the strings. – lballes Jul 01 '16 at 06:11
Indeed, I made the assumption of just matching the start. – AChampion Jul 01 '16 at 06:12
Sure, just adding this as an extra piece of information – lballes Jul 01 '16 at 06:13

score 0 · Answer 2 · answered Jul 01 '16 at 06:12

First, fix your code:

id  = "77bb1b03" # needs to be a string
id_list = ['List of devices attached ', '572ea01e\tdevice', '77bb1b03\tdevice', '']

Then loop over the list and compare each string individually:

for s in id_list:
    if id in s:
        print "id %s present"%id
        break
else:
    print "id %s not present"%id

Devi Prasad Khatua · Answer 3 · 2016-07-01T06:38:48.770

0

Check this out:
Single liner as you demanded and id is a string!

>>> from __future__ import print_function
... id  = '77bb1b03'
... id_list = ['List of devices attached ', '572ea01e\tdevice', '77bb1b03\tdevice', '']
... [print(item, 'ID present') for item in id_list if item and item.find(id)!=-1]
77bb1b03    device ID present

Thanks @Achampion for the left -> right execution !

edited Jul 01 '16 at 06:38

answered Jul 01 '16 at 06:15

Devi Prasad Khatua

1,185
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Cause check for `''` and `None` – Devi Prasad Khatua Jul 01 '16 at 06:33
For `None` you would need `item and item.find()` or it will error. And it's unnecessary for `''` the `find()` will already have failed the `!= -1`. – AChampion Jul 01 '16 at 06:35
Yes right you are, I was mainly skeptical for `''` thanks! – Devi Prasad Khatua Jul 01 '16 at 06:38

score 0 · Answer 4 · answered Jul 01 '16 at 08:55

A nasty, obscure, slower alternative to those that will/are shown. The id var seems to prefix list items, but not sure if you would ever have need to find the id "somewhere" inside a list element.

id  = 77bb1b03
id_list = ['List of devices attached ', '572ea01e\tdevice', '77bb1b03\tdevice', '']
if len(filter(lambda id_list_item: id_list_item.find(id) >=0 , id_list)):
    print "id present"
else:
    print "id not present"

how do I match an element with a list?

4 Answers4