python - Is there a way to copy only the structure (not the data) of a Pandas DataFrame?

Question

I received a DataFrame from somewhere and want to create another DataFrame with the same number and names of columns and rows (indexes). For example, suppose that the original data frame was created as

import pandas as pd
df1 = pd.DataFrame([[11,12],[21,22]], columns=['c1','c2'], index=['i1','i2'])

I copied the structure by explicitly defining the columns and names:

df2 = pd.DataFrame(columns=df1.columns, index=df1.index)    

I don't want to copy the data, otherwise I could just write df2 = df1.copy(). In other words, after df2 being created it must contain only NaN elements:

In [1]: df1
Out[1]: 
    c1  c2
i1  11  12
i2  21  22

In [2]: df2
Out[2]: 
     c1   c2
i1  NaN  NaN
i2  NaN  NaN

Is there a more idiomatic way of doing it?

Answer 1

That's a job for reindex_like. Start with the original:

df1 = pd.DataFrame([[11, 12], [21, 22]], columns=['c1', 'c2'], index=['i1', 'i2'])

Construct an empty DataFrame and reindex it like df1:

pd.DataFrame().reindex_like(df1)
Out: 
    c1  c2
i1 NaN NaN
i2 NaN NaN