python equivalent of filter() getting two output lists (i.e. partition of a list)

by

Try this:

def partition(pred, iterable):
    trues = []
    falses = []
    for item in iterable:
        if pred(item):
            trues.append(item)
        else:
            falses.append(item)
    return trues, falses

Usage:

>>> trues, falses = partition(lambda x: x > 10, [1,4,12,7,42])
>>> trues
[12, 42]
>>> falses
[1, 4, 7]

There is also an implementation suggestion in itertools recipes:

from itertools import filterfalse, tee

def partition(pred, iterable):
    'Use a predicate to partition entries into false entries and true entries'
    # partition(is_odd, range(10)) --> 0 2 4 6 8   and  1 3 5 7 9
    t1, t2 = tee(iterable)
    return filterfalse(pred, t1), filter(pred, t2)

The recipe comes from the Python 3.x documentation. In Python 2.x filterfalse is called ifilterfalse.

More Related Contents:

  1. Can we implement our own reduce and filter functions? [closed]
  2. Select nan column in pandas
  3. How to filter a dictionary according to an arbitrary condition function?
  4. Using strides for an efficient moving average filter
  5. How can I remove non-ASCII characters but leave periods and spaces?
  6. Efficient way to apply multiple filters to pandas DataFrame or Series
  7. List comprehension vs. lambda + filter
  8. Django filter queryset __in for *every* item in list
  9. Calling filter returns [duplicate]
  10. How to use filter, map, and reduce in Python 3
  11. How can I filter a date of a DateTimeField in Django?
  12. how do you filter pandas dataframes by multiple columns
  13. How to check if one dictionary is a subset of another larger dictionary?
  14. Python pandas – filter rows after groupby
  15. Python: filter list of list with another list
  16. SqlAlchemy – Filtering by Relationship Attribute
  17. Efficient thresholding filter of an array with numpy
  18. Filter string data based on its string length
  19. how to keep elements of a list based on another list [duplicate]
  20. remove None value from a list without removing the 0 value
  21. Dynamically filtering a pandas dataframe
  22. Python: filtering lists by indices
  23. Why does foo = filter(…) return a , not a list? [duplicate]
  24. Pandas slicing FutureWarning with 0.21.0
  25. Python’s in (__contains__) operator returns a bool whose value is neither True nor False
  26. Removing u in list
  27. Fully transparent windows in Pygame?
  28. How to update/upgrade a package using pip?
  29. Change bar color according to hue name
  30. urllib2 and json

Leave a Comment