dask.bag.Bag.starmap

dask.bag.Bag.starmap¶

Bag.starmap(func, **kwargs)[source]¶

Apply a function using argument tuples from the given bag.

This is similar to itertools.starmap, except it also accepts keyword arguments. In pseudocode, this is could be written as:

>>> def starmap(func, bag, **kwargs):
...     return (func(*args, **kwargs) for args in bag)

Parameters

funccallable
**kwargsItem, Delayed, or object, optional: Extra keyword arguments to pass to func. These can either be normal objects, dask.bag.Item, or dask.delayed.Delayed.

Examples

>>> import dask.bag as db
>>> data = [(1, 2), (3, 4), (5, 6), (7, 8), (9, 10)]
>>> b = db.from_sequence(data, npartitions=2)

Apply a function to each argument tuple:

>>> from operator import add
>>> b.starmap(add).compute()
[3, 7, 11, 15, 19]

Apply a function to each argument tuple, with additional keyword arguments:

>>> def myadd(x, y, z=0):
...     return x + y + z
>>> b.starmap(myadd, z=10).compute()
[13, 17, 21, 25, 29]

Keyword arguments can also be instances of dask.bag.Item or dask.delayed.Delayed:

>>> max_second = b.pluck(1).max()
>>> max_second.compute()
10
>>> b.starmap(myadd, z=max_second).compute()
[13, 17, 21, 25, 29]

dask.bag.Bag.repartition

dask.bag.Bag.std