CODEWITHSUNDEEP
pythonpython-2.7
user765443
user765443

Reputation: 1892

elegant way to filter list

I have two list like following way.I need to extract value from after = i.e. xyz and .81. I am trying to make one general solution for both list or make for future also. As of now, I was doing join and find int the list than split. But I feel it can be done in better way.

a = ['.TITLE', "'=", 'xyz', 'vdd', '=', '0.81', 'temp', "-40'"]
b = ['.TITLE', "'$", 'abc', '=', 'xyz', 'vdd', '=', '0.99', 'temp', "125'"]

Upvotes: 5

Views: 137

Answers (3)

ychaouche
ychaouche

Reputation: 5092

A non elegant way would be to use flags : 

a = ['.TITLE', "=", 'xyz', 'vdd', '=', '0.81', 'temp', "-40'"]
b = ['.TITLE', "'$", 'abc', '=', 'xyz', 'vdd', '=', '0.99', 'temp', "125'"]

def extract(L,sep="="):
    pick_this_one = False
    for item in L :
        if pick_this_one:
            pick_this_one = False
            yield item
        if item == sep :
            pick_this_one = True

for value in extract(a+b):
    print value

>>> xyz
0.81
xyz
0.99
>>>

Upvotes: 0

Inbar Rose
Inbar Rose

Reputation: 43437

As a function:

import itertools

def extract_items_after(lst, marker='='):
    for x, y in itertools.izip_longest(lst, lst[1:]):
        if marker in x:
            yield y

Using your data:

a = ['.TITLE', "'=", 'xyz', 'vdd', '=', '0.81', 'temp', "-40'"]
b = ['.TITLE', "'$", 'abc', '=', 'xyz', 'vdd', '=', '0.99', 'temp', "125'"]

for l in [a, b]:
    print list(extract_items_after(l))

Results:

>>> 
['xyz', '0.81']
['xyz', '0.99']

Upvotes: 4

TerryA
TerryA

Reputation: 59974

You could use next() with a generator:

a = ['.TITLE', "'=", 'xyz', 'vdd', '=', '0.81', 'temp', "-40'"]
a1 = iter(a)
for item in a1:
    if '=' in item:
        print next(a1)

Prints:

xyz
0.81

Note that if = is the last item, this will raise a StopIteration error.

You could also use enumerate():

a = ['.TITLE', "'=", 'xyz', 'vdd', '=', '0.81', 'temp', "-40'"]
for i, j in enumerate(a):
    if '=' in j:
        print a[i+1]

Prints:

xyz
0.81

Once again this will raise an error (IndexError) if = is the last item.

Upvotes: 6

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