melt pandas dataframe and divide two rows based on column

Question

I have a dataFrame of the form:

                   0
college     gender  
Engineering F      117
            M      2240

and I want to change it to:

college       M:F
Engineering   19:1

where M:F represents the ratio of Male to Female.

Is there anyway to do this with pandas without iterating over all rows?

Answer 1

It seems you need reshape by unstack and then divide:

df = df.unstack()[0]
#same as
#df = df[0].unstack()

df['M:F'] = df['M'] / df['F']
#same as
#df['M:F']  = df['M'].div(df['F'])

---

print (df)
                        0
college      gender      
Engineering  F        117
             M       2240
Engineering1 F        117
             M       2240

df = df.unstack()[0]
df['M:F']  = df['M'].div(df['F'])
print (df)
gender          F     M        M:F
college                           
Engineering   117  2240  19.145299
Engineering1  117  2240  19.145299

print (df[['M:F']])
gender              M:F
college                
Engineering   19.145299
Engineering1  19.145299