使用if语句针对另一列在pandas数据框中创建新列

Question

I need to calculate a new column in my dataframe using a if in the calculation but have no luck with anything I have tried. This is what I have

     OrderNum  Discount  OrderQty  UnitPrice  REMAININGQTY
0    115702       0.0      25.0     145.00          25.0
1    115793       0.0      20.0     823.00          20.0
2    115793       0.0      20.0     823.00          20.0
3    116282       0.0       1.0     699.95           1.0
4    116765       0.0      36.0     295.00           6.0

This is what I need.

column = PricePer

the calculation = IIf(df.discount<>0,df.unitprice-(df.discount/df.orderqty),df.unitprice)

How do I accomplish this?

Answer 1

Try:

df['Price Per'] = pd.np.where(df.Discount != 0, df.UnitPrice - (df.Discount / df.OrderQty), df.UnitPrice)

Output:

  OrderNum  Discount  OrderQty  UnitPrice  REMAININGQTY  Price Per
0    115702       0.0      25.0     145.00          25.0     145.00
1    115793       0.0      20.0     823.00          20.0     823.00
2    115793       0.0      20.0     823.00          20.0     823.00
3    116282       0.0       1.0     699.95           1.0     699.95
4    116765       0.0      36.0     295.00           6.0     295.00

Answer 2

You might also use these 2 statements

df.loc[df['Discount'] == 0, 'PricePer'] = df['UnitPrice']
df.loc[df['Discount'] != 0, 'PricePer'] = df['UnitPrice']-df['Discount']/df['OrderQty']

But if discount equals zero, the -(discount / orderqty) would be zero, no if is needed ? So I would think this might also do:

df['PricePer'] = df['UnitPrice']-df['Discount']/df['OrderQty']