pandas convert columns to percentages of the totals

You could use the .apply() method:

df = df.apply(lambda x: x/sum(x)*100, axis=1)

Tim Tian's answer pretty much worked for me, but maybe this helps if you have a df with several columns and want to do a % column wise.

df_pct = df/df[df.columns].sum()*100

I was having trouble because I wanted to have the result of a pd.pivot_table expressed as a %, but couldn't get it to work. So I just used that code on the resulting table itself and it worked.

You can do this using basic pandas operators .div and .sum, using the axis argument to make sure the calculations happen the way you want:

cols = ['<80%', '80-90', '>90']
df[cols] = df[cols].div(df[cols].sum(axis=1), axis=0).multiply(100)

• Calculate the sum of each column (df[cols].sum(axis=1). axis=1 makes the summation occur across the rows, rather than down the columns.
• Divide the dataframe by the resulting series (df[cols].div(df[cols].sum(axis=1), axis=0). axis=0 makes the division happen across the columns.
• To finish, multiply the results by 100 so they are percentages between 0 and 100 instead of proportions between 0 and 1 (or you can skip this step and store them as proportions).

df/df.sum()

If you want to divide the sum of rows, transpose it first.