Random Pandas Notes, Note 1

To change a row value based on more than one conditions, use the following:

df['A'] = np.where(((df['B'] == 'some_value') & (df['C'] == 'some_other_value')), true_value, false_value)

Another equally efficient approach is using loc:
Note that this method does not give a default value when the condition is not met. So, the same code might be required to run twice or using .fillna() method.

df.loc[(df.B == 'some_value') | (df.C == 'some_other_value'), 'A'] = true_value

ps: for ‘and’ or ‘or’ operation, use symbol ‘&’ or ‘|’.