Change iteration rate on itertools

I have this iteration count using iter tools:

for i in itertools.count(start=2**68):

And I want it to bump up an exponent every time (68,69,70,71,…). Is there support for this in itertools? I have looked at the step option on the itertools documentation, but don’t see any way to change by exponential type only float, integer.

Answers:

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Method 1

There is not a function specially made for that, but it’s very easy to make what you want from basic components:

for i in map(lambda i: 2**i, itertools.count(start=68)):

Incidentally, one of the comments says map(lambda...) is an antipattern, and should instead be replaced with generator expressions. Here is how to do in case you wonder.

for i in (2**i for i in itertools.count(start=68)):

Method 2

Use itertools.count for the exponent, and do the exponentiation separately:

for exponent in itertools.count(start=68):
    i = 2 ** exponent
    print(i)

Method 3

To piggyback on the great answers by Barmar and Blackbeans, map may be used without lambda to achieve a solution.

import itertools
import functools
import math
pow_base2 = functools.partial(math.pow, 2)
for i in map(pow_base2, itertools.count(start=68)):
    print(i)

Or if you don’t want to deal with floatS (thanks Kelly Bundy for the suggestion).

import itertools
import functools
pow_base2 = functools.partial(pow, 2)
for i in map(pow_base2, itertools.count(start=68)):
    print(i)

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0