:class:`~fractions.Fraction`.) If the input iterable is empty, the
output iterable will also be empty.
- Equivalent to::
+ Roughly equivalent to::
def accumulate(iterable, func=operator.add):
'Return running totals'
Make an iterator that returns elements from the first iterable until it is
exhausted, then proceeds to the next iterable, until all of the iterables are
exhausted. Used for treating consecutive sequences as a single sequence.
- Equivalent to::
+ Roughly equivalent to::
def chain(*iterables):
# chain('ABC', 'DEF') --> A B C D E F
value. So if the input elements are unique, there will be no repeat
values in each combination.
- Equivalent to::
+ Roughly equivalent to::
def combinations(iterable, r):
# combinations('ABCD', 2) --> AB AC AD BC BD CD
value. So if the input elements are unique, the generated combinations
will also be unique.
- Equivalent to::
+ Roughly equivalent to::
def combinations_with_replacement(iterable, r):
# combinations_with_replacement('ABC', 2) --> AA AB AC BB BC CC
Make an iterator that filters elements from *data* returning only those that
have a corresponding element in *selectors* that evaluates to ``True``.
Stops when either the *data* or *selectors* iterables has been exhausted.
- Equivalent to::
+ Roughly equivalent to::
def compress(data, selectors):
# compress('ABCDEF', [1,0,1,0,1,1]) --> A C E F
Make an iterator that returns evenly spaced values starting with number *start*. Often
used as an argument to :func:`map` to generate consecutive data points.
- Also, used with :func:`zip` to add sequence numbers. Equivalent to::
+ Also, used with :func:`zip` to add sequence numbers. Roughly equivalent to::
def count(start=0, step=1):
# count(10) --> 10 11 12 13 14 ...
Make an iterator returning elements from the iterable and saving a copy of each.
When the iterable is exhausted, return elements from the saved copy. Repeats
- indefinitely. Equivalent to::
+ indefinitely. Roughly equivalent to::
def cycle(iterable):
# cycle('ABCD') --> A B C D A B C D A B C D ...
Make an iterator that drops elements from the iterable as long as the predicate
is true; afterwards, returns every element. Note, the iterator does not produce
*any* output until the predicate first becomes false, so it may have a lengthy
- start-up time. Equivalent to::
+ start-up time. Roughly equivalent to::
def dropwhile(predicate, iterable):
# dropwhile(lambda x: x<5, [1,4,6,4,1]) --> 6 4 1
Make an iterator that filters elements from iterable returning only those for
which the predicate is ``False``. If *predicate* is ``None``, return the items
- that are false. Equivalent to::
+ that are false. Roughly equivalent to::
def filterfalse(predicate, iterable):
# filterfalse(lambda x: x%2, range(10)) --> 0 2 4 6 8
groups.append(list(g)) # Store group iterator as a list
uniquekeys.append(k)
- :func:`groupby` is equivalent to::
+ :func:`groupby` is roughly equivalent to::
class groupby:
# [k for k, g in groupby('AAAABBBCCDAABBB')] --> A B C D A B
specified position. Unlike regular slicing, :func:`islice` does not support
negative values for *start*, *stop*, or *step*. Can be used to extract related
fields from data where the internal structure has been flattened (for example, a
- multi-line report may list a name field on every third line). Equivalent to::
+ multi-line report may list a name field on every third line). Roughly equivalent to::
def islice(iterable, *args):
# islice('ABCDEFG', 2) --> A B
value. So if the input elements are unique, there will be no repeat
values in each permutation.
- Equivalent to::
+ Roughly equivalent to::
def permutations(iterable, r=None):
# permutations('ABCD', 2) --> AB AC AD BA BC BD CA CB CD DA DB DC
Cartesian product of input iterables.
- Equivalent to nested for-loops in a generator expression. For example,
+ Roughly equivalent to nested for-loops in a generator expression. For example,
``product(A, B)`` returns the same as ``((x,y) for x in A for y in B)``.
The nested loops cycle like an odometer with the rightmost element advancing
repetitions with the optional *repeat* keyword argument. For example,
``product(A, repeat=4)`` means the same as ``product(A, A, A, A)``.
- This function is equivalent to the following code, except that the
+ This function is roughly equivalent to the following code, except that the
actual implementation does not build up intermediate results in memory::
def product(*args, repeat=1):
Make an iterator that returns *object* over and over again. Runs indefinitely
unless the *times* argument is specified. Used as argument to :func:`map` for
invariant parameters to the called function. Also used with :func:`zip` to
- create an invariant part of a tuple record. Equivalent to::
+ create an invariant part of a tuple record.
+
+ Roughly equivalent to::
def repeat(object, times=None):
# repeat(10, 3) --> 10 10 10
the iterable. Used instead of :func:`map` when argument parameters are already
grouped in tuples from a single iterable (the data has been "pre-zipped"). The
difference between :func:`map` and :func:`starmap` parallels the distinction
- between ``function(a,b)`` and ``function(*c)``. Equivalent to::
+ between ``function(a,b)`` and ``function(*c)``. Roughly equivalent to::
def starmap(function, iterable):
# starmap(pow, [(2,5), (3,2), (10,3)]) --> 32 9 1000
.. function:: takewhile(predicate, iterable)
Make an iterator that returns elements from the iterable as long as the
- predicate is true. Equivalent to::
+ predicate is true. Roughly equivalent to::
def takewhile(predicate, iterable):
# takewhile(lambda x: x<5, [1,4,6,4,1]) --> 1 4
The following Python code helps explain what *tee* does (although the actual
implementation is more complex and uses only a single underlying
- :abbr:`FIFO (first-in, first-out)` queue)::
+ :abbr:`FIFO (first-in, first-out)` queue).
+
+ Roughly equivalent to::
def tee(iterable, n=2):
it = iter(iterable)
Make an iterator that aggregates elements from each of the iterables. If the
iterables are of uneven length, missing values are filled-in with *fillvalue*.
- Iteration continues until the longest iterable is exhausted. Equivalent to::
+ Iteration continues until the longest iterable is exhausted. Roughly equivalent to::
class ZipExhausted(Exception):
pass
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