Pandas - Get first row value of a given column

Question

This seems like a ridiculously easy question... but I\'m not seeing the easy answer I was expecting.

So, how do I get the value at an nth row of a given column in Pa

Answer 1

Note that the answer from @unutbu will be correct until you want to set the value to something new, then it will not work if your dataframe is a view.

In [4]: df = pd.DataFrame({'foo':list('ABC')}, index=[0,2,1])
In [5]: df['bar'] = 100
In [6]: df['bar'].iloc[0] = 99
/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas-0.16.0_19_g8d2818e-py2.7-macosx-10.9-x86_64.egg/pandas/core/indexing.py:118: SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame

See the the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
  self._setitem_with_indexer(indexer, value)

Another approach that will consistently work with both setting and getting is:

In [7]: df.loc[df.index[0], 'foo']
Out[7]: 'A'
In [8]: df.loc[df.index[0], 'bar'] = 99
In [9]: df
Out[9]:
  foo  bar
0   A   99
2   B  100
1   C  100