How to get a single value as a string from pandas dataframe

If you can guarantee only one result is returned, use loc and call item:

>>> df.loc[df['Host'] == 'a', 'Port'].item()
'b'

Or, similarly,

>>> df.loc[df['Host'] == 'a', 'Port'].values[0]
'b'

…to get the first value (similarly, .values[1] for the second). Which is better than df.loc[df['Host'] == 'a', 'Port'][0] because, if your DataFrame looks like this,

  Host Port
1    a    b

Then “KeyError: 0” will be thrown—

df.loc[df['Host'] == 'a', 'Port'][0]
---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)

Alternatively, use at:

>>> df.at[df['Host'].eq('a').idxmax(), 'Port']
'b'

The drawback is that if ‘a’ doesn’t exist, idxmax will return the first index (and return an incorrect result).