How to change value for rows that meet specific conditions in pandas?

Question

I want to change the name in the name column to default for only rows that meet a specific condition (name == None and weight == 1). As you can see weight can be 10, but I do not want to change the names for weights of 10. Here is a small example dataframe:

post   name  weight  response
blah1  None       1       yes
blah2  None      10        no
blah3  Annie      1       yes

How can I achieve this in a simple way?

Answer 1

a fast, solid, robust Panda-esque solution:

df.loc[(df.name == None) & (df.weight == 1), 'name'] = 'defaut'