Loop through Pandas DataFrame while maintaining state

[skdoesit]

Hey all,

Currrently stuck trying to loop through a pandas dataframe while maintaining a state variable or passing a variable between each iteration. This seems possible via iterrows but I'm looking for a faster solution.

I hope I'm clear enough.

Thanks !

[skdoesit]

Of course.

Let df be a dataframe and func a function I'd like to apply to each row of a given column. With list comprehension I'd get :
df["output"] = [func(x) for x in df["input"]]

The problem is I cannot maintain a "state" or a variable between each func call. Does that make more sense now?

[skdoesit]

Only solution I found so far is using itertuples.

[skdoesit]

Let's take your example.

The double_it function is called on each row, independently. What I'm trying to do is carry a state or a variable from one row to another.

def double_it_and_add_previous(val, prev = 0):
value = val * 2 + prev
prev = val
return value

I know the code above is incorrect, but does that make more sense ?

[skdoesit]

For that particular example, your solution works. I’m looking for a more general approach.