Conditional If Statement: If value in row contains string ... set another column equal to string

I assume you are using pandas, then you can use numpy.where, which is a vectorized version of if/else, with the condition constructed by str.contains:

df['Activity_2'] = pd.np.where(df.Activity.str.contains("email"), "email",                   pd.np.where(df.Activity.str.contains("conference"), "conference",                   pd.np.where(df.Activity.str.contains("call"), "call", "task")))df#   Activity            Activity_2#0  email personA       email#1  attend conference   conference#2  send email          email#3  call Sam            call#4  random text         task#5  random text         task#6  lwantto call        call

This also works:

df.loc[df['Activity'].str.contains('email'), 'Activity_2'] = 'email'df.loc[df['Activity'].str.contains('conference'), 'Activity_2'] = 'conference'df.loc[df['Activity'].str.contains('call'), 'Activity_2'] = 'call'

The current solution behaves wrongly if your df contains NaN values. In that case I recommend using the following code which worked for me

temp=df.Activity.fillna("0")df['Activity_2'] = pd.np.where(temp.str.contains("0"),"None",                   pd.np.where(temp.str.contains("email"), "email",                   pd.np.where(temp.str.contains("conference"), "conference",                   pd.np.where(temp.str.contains("call"), "call", "task"))))