CODEWITHSUNDEEP
pythonpandaspython-3.6
acakaliman
acakaliman

Reputation: 83

Why is this simple reindex Panda df function not working?

I'm trying to reindex dataframes within a function but it's not working. It works outside of the function so I'm totally lost. Here's what I'm doing:

Reindexing df2 based on index from df1

Outside of function:

df2 = df2.reindex(df1.index)

This result is what I want ,and works. However, within this function:

def reindex_df(a,b):
    a = a.reindex(b.index)

where a = df2 and b = df1.

What's going on here? I've researched and thought something to do with local vs. global variables, but tweaked code (to this) and still not working. What am I missing????

Upvotes: 0

Views: 121

Answers (1)

Valdi_Bo
Valdi_Bo

Reputation: 30991

Compare 2 following examples:

  1. A function substituting a new value under a parameter:

    def f1(a):
    a = a + 1

a = 10
print(f'Before: {a}')
f1(a)
print(f'After:  {a}')

    The result is:

    Before: 10
After:  10

    so that the substitution in f1 is not visible outside this function.

  2. A function returning the new value:

    def f2(a):
    return a + 1

a = 10
print(f'Before: {a}')
a = f2(a)
print(f'After:  {a}')

    This time the result is:

    Before: 10
After:  11

So change your function the same way. It should return the new (reindexed) DataFrame and when you call it, substitute the result under the same variable.

Upvotes: 1

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