BUG/ERR: read_csv(header=[0]) should raise/warn · Issue #7757 · pandas-dev/pandas (original) (raw)
read_csv with a single-row header either breaks any names that might be on the index, or reads all data as NaN. This problem might exist because pd.read_csv hasn't caught up to #7589.
In [1]: import pandas as pd
In [2]: from StringIO import StringIO
In [3]: pd.read_csv(StringIO('''
alpha,,A,B
foo,bar,,
this,x,1,2
this,y,5,6
that,x,3,4
that,y,7,8'''), header=0, index_col=[0,1])
Out[3]:
A B
alpha Unnamed: 1
foo bar NaN NaN
this x 1 2
y 5 6
that x 3 4
y 7 8
In [4]: pd.read_csv(StringIO('''
alpha,,A,B
foo,bar,,
this,x,1,2
this,y,5,6
that,x,3,4
that,y,7,8'''), header=[0], index_col=[0,1])
Out[4]:
alpha A B
foo bar
this x NaN NaN
y NaN NaN
that x NaN NaN
y NaN NaN
In [5]: pd.read_csv(StringIO('''
alpha,,A,B
beta,,Y,Z
foo,bar,,
this,x,1,2
this,y,5,6
that,x,3,4
that,y,7,8'''), header=[0,1], index_col=[0,1])
Out[5]:
alpha A B
beta Y Z
foo bar
this x 1 2
y 5 6
that x 3 4
y 7 8