CODEWITHSUNDEEP
pythonpandas
sanguineturtle
sanguineturtle

Reputation: 1455

Pandas: Why does DataFrame.drop(labels) return a DataFrame with removed label name

When I drop some variables from a DataFrame, dataframe return as I expect except the when index.name is removed. Why would this be?

Example:

test = pd.DataFrame([[1,2,3],[3,4,5],[5,6,7]], index=['a','b','c'], columns=['d','e','f'])
test

Out[20]:
second  d   e   f
first           
a   1   2   3
b   3   4   5
c   5   6   7
#test.index.name = first
#test.columns.name=second
In [27]:

test.drop(['b'])

Out[27]:
second  d   e   f
a   1   2   3
c   5   6   7

After 'b' is dropped the returned dataframe (index.name) is no longer 'first' but None.

Q1. Is it because the .drop() method returns a dataframe that has a new index object which by default would have no name?
Q2. Is there anyway to preserve the index.name during drop operations as the newindex is still correctly named - it is just a subset of the original index

Expected Output would be: 

 Out[20]:
    second  d   e   f
    first           
    a   1   2   3
    c   5   6   7

Upvotes: 0

Views: 3104

Answers (1)

sanguineturtle
sanguineturtle

Reputation: 1455

One way to achieve the intended behavior is:

row_name = test.index.name
test = test.drop('b')
test.index.name = row_name

But this isn't ideal.

Upvotes: 1

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