CODEWITHSUNDEEP
python
user3316195
user3316195

Reputation: 29

Python: Split a list into two. One list of floats, one list of strings

I have a list that contains floats and strings ex: [1.456, 'upn', 7.965, 'bvb'] How can I separate these into two lists that would read [1.456, 7.95] and ['upn' , 'bvb']

Upvotes: 1

Views: 138

Answers (6)

alvas
alvas

Reputation: 122112

If you have more than strings and float, you can try sorting the elements in a list by their type(x), see http://docs.python.org/2/library/types.html: 

>>> from collections import defaultdict
>>> lst = [1.456, 'upn', 7.965, 'bvb']
>>> ddict = defaultdict(list)
>>> for i in lst:
...     ddict[type(i)].append(i)
... 
>>> for i in ddict:
...     print i, ddict[i]
... 
<type 'float'> [1.456, 7.965]
<type 'str'> ['upn', 'bvb']

Upvotes: 0

Tanveer Alam
Tanveer Alam

Reputation: 5275

>>> mixed_list = [1.456, 'upn', 7.965, 'bvb']
>>> temp_list = sorted(mixed_list)
>>> output_tuple = next( (temp_list[:temp_list.index(i):1],temp_list[temp_list.index(i):]) for i in temp_list if type(i) == str)
>>> output_tuple[0]
[1.456, 7.965]
>>> output_tuple[1]
['bvb', 'upn']

>>> sorted(mixed_list)
[1.456, 7.965, 'bvb', 'upn']

Here first I have sorted the list which arranges them in float and string order. Then I have used next as iterator to check for first occurrence of 'string' and as soon as I get string the iterator will stop and give us the result. It seems little complicated but it is faster then other methods where you have to iterate over whole list.
It can be very efficient if you have a big input list.

Upvotes: 0

Christian Tapia
Christian Tapia

Reputation: 34146

One way would be using slicing some_list[start:end:step]:

b = a[::2]
c = a[1::2]

print b
print c

Output:

[1.456, 7.965]
['upn', 'bvb']

Note: This approach will only work if the list follows the pattern [float, str, float, str...]

Upvotes: 2

nathancahill
nathancahill

Reputation: 10850

For Python 2.x:

lst = [1.456, 'upn', 7.965, 'bvb']
[i for i in lst if isinstance(i, basestring)]
[i for i in lst if isinstance(i, float)]

For Python 3.x:

lst = [1.456, 'upn', 7.965, 'bvb']
[i for i in lst if isinstance(i, str)]
[i for i in lst if isinstance(i, float)]

Output:

['upn', 'bvb']
[1.456, 7.965]

Upvotes: 3

kylieCatt
kylieCatt

Reputation: 11039

float_list = []
string_list = []
for item in first_list:
    if isinstance(item, float):
        float_list.append(item)
    elif isinstance(item, str):
        string_list.append(item)

Upvotes: 3

markcial
markcial

Reputation: 9323

filter(lambda x:type(x) == str,[1.456, 'upn', 7.965, 'bvb'])
filter(lambda x:type(x) == float,[1.456, 'upn', 7.965, 'bvb'])

Upvotes: 1

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