如何在Dataframe中查找字段的百分比份额？

Question

I have a Pandas DataFrame like below

df = pd.DataFrame({"ID" : [1,2,3,4],
                   "Amt" : [100, 200,  300, 400]})

My obejective is to find the percentage share of each amount and create a new field in this dataframe with it. My final DataFrame should look like

ID Amt Avg
1  100 10
2  200 20
3  300 30
4  400 40

To achieve this, I concatenated the Amt field to same DF. Then renamed it to Avg. and then calculated the perc using iterator

   df = pd.concat([df, df['Amt']], axis=1)
   df.columns=(['ID', 'Amt', 'Avg'])
   for i in range(0,len(df)):
       df['Avg'] = ((df['Avg']/df['Amt'].sum())*100)

I'm new to this. I've seen many achieve difficult objective with much simpler code.
So can someone please help me to know the better approach than this one?

Answer 1

I believe you need:

df['Avg'] = df['Amt']/df['Amt'].sum()*100
print (df)
   ID  Amt   Avg
0   1  100  10.0
1   2  200  20.0
2   3  300  30.0
3   4  400  40.0