Pandas reset index is not taking effect

Question

I’m not sure where I am astray but I cannot seem to reset the index on a dataframe.

When I run test.head(), I get the output below:

test.head

As you can see, the dataframe is a slice, so the index is out of bounds.
What I’d like to do is to reset the index for this dataframe. So I run test.reset_index(drop=True). This outputs the following:

reset

That looks like a new index, but it’s not. Running test.head again, the index is still the same. Attempting to use lambda.apply or iterrows() creates problems with the dataframe.

How can I really reset the index?

Asked By: Union find

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Source

Answer 1

reset_index by default does not modify the DataFrame; it returns a new DataFrame with the reset index. If you want to modify the original, use the inplace argument: df.reset_index(drop=True, inplace=True). Alternatively, assign the result of reset_index by doing df = df.reset_index(drop=True).

Answered By: BrenBarn

Answer 2

BrenBarn’s answer works.

The following also worked via this thread, which isn’t a troubleshooting so much as an articulation of how to reset the index:

test = test.reset_index(drop=True)

Answered By: Union find

Answer 3

I would add to in code veritas’s answer:

If you already have an index column specified, then you can save the del, of course. In my hypothetical example:

    df_total_sales_customers = pd.DataFrame({'Sales': total_sales_customers['Sales'],
                              'Customers': total_sales_customers['Customers']}, index = total_sales_customers.index)

    df_total_sales_customers = df_total_sales_customers.reset_index()

Answered By: Subspacian

Answer 4

As an extension of in code veritas‘s answer… instead of doing del at the end:

test = test.reset_index()
del test['index']

You can set drop to True.

test = test.reset_index(drop=True)

Answered By: Wendao Liu

Pandas reset index is not taking effect

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