In python list comprehension can we look at previous values created during execution

Question

I have a dictionary and as I am creating it during list comprehension can I access the previous values created?

Example:

h = {i:1+h[i-1] for i in range(1,100))}

Answer 1

Edit: I read i:i + h[i-1] instead of i:1 + h[i-1] . The latter is always equal to i:i except in the first case, when it is 1+None

This does what you want in a dictionary comprehension. Requires Python 3.2 or higher:

from itertools import accumulate 
h = {i:v for i,v in enumerate(accumulate(range(100)))}

otherwise use this

def accumulate(r):
    next_value = 0
    for i in r:
        next_value = next_value + i
        yield next_value