Trying to change a single value in pandas dataframe

Question

I've seen a bunch of questions with similar titles but I still cant figure it out. All I want to do is replace the value thats in my dataframe in the fifth row and 5th column with the value 100. I thought simply this would do the trick

df.loc['cheerios','rating']= 100

since cheerios is the row and rating is the column

    name        sugar  sodium rating
0   fruit loop       x      x     x
1   trix             x      x     x
2   oreo             x      x     x
3  cocoa puff        x      x     x
4  cheerio           x      x     100

Answer 1

.loc is an indexer. It looks for an entry in the index, but the column name is not an index. It is simply a column. The following solutions would work:

df.loc[4, 'rating'] = 100 # Because 4 is in the index, but how do you know?

or:

df.loc[df['name']=='cheerio', 'rating'] = 100 # Find the row by column

or:

df.set_index('name', inplace=True) # Make 'name' the index
df.loc['cheerios', 'rating'] = 100     # Use the indexer