Struggling to insert values into a new column-CodePudding

I am facing a problem. I have created a new column in my csv file and I am trying to add values in the column but don't know what functions to use. The column is called 'Discounted_Price' and I have to mentioned that for Ford and Chevrolet, the prices have a ten percent discount. This is the code up to this point:

CarPrices_discount=pd.read_csv('C:\\Users\\Jon\\Desktop\\data science\\car_prices.csv')
CarPrices_discount
CarPrices_discount.insert(15,'Discounted_Price',np.nan)
CarPrices_discount.head()
Ford_Chev=CarPrices_discount[(CarPrices_discount.make=='Ford')|(CarPrices_discount.make=='Chevrolet')]  
#Ford_Chev['Discounted_Price']=Ford_Chev['sellingprice']*0.9
CarPrices_discount.loc[CarPrices_discount.Ford_Chev['Discounted_Price']=Ford_Chev['sellingprice']*0.9

I know the last line is wrong but I do not how to insert it with dataframe.loc.

CodePudding user response：

Data:

>>> import pandas as pd
>>> import numpy as np
>>> CarPrices_discount = pd.DataFrame({"make" : ['Chevrolet', 'a', 'b', 'Ford', 'Chevrolet', 'Ford'],
                                       "sellingprice" : [900, 10,20,20,40,30]})
>>> CarPrices_discount

    make        sellingprice
0   Chevrolet   900
1   a           10
2   b           20
3   Ford        20
4   Chevrolet   40
5   Ford        30


>>> CarPrices_discount['Discounted_Price'] = CarPrices_discount.apply(lambda x:x.sellingprice*0.9 if x.make in ['Ford', 'Chevrolet'] else np.nan, axis=1)
>>> CarPrices_discount
    make        sellingprice    Discounted_Price
0   Chevrolet   900             810.0
1   a           10              NaN
2   b           20              NaN
3   Ford        20              18.0
4   Chevrolet   40              36.0
5   Ford        30              27.0

CodePudding user response：

Ok, I found an answer of some sort but it is highly flawed:

Ford_Chev=CarPrices_discount[(CarPrices_discount.make=='Ford'(CarPrices_discount.make=='Chevrolet')] print(Ford_Chev) 
  Ford_Chev['Discounted_Price']=Ford_Chev["sellingprice"]*0.9 
  print(Ford_Chev)