Python Pandas: pass column name as argument inte function

Question

I have a DataFrame, df, with article numbers as columns (hundreds) and dates as index rows. df contains the number of sold items per product and day. This is a simplified example of it:

df = pd.DataFrame({'banana': [1, 8], 'apple': [3, 6]})

which outputs:

             banana   apple
2023-01-01   1        3
2023-01-02   8        6

I have a dictionary with prices:

price_dict = {'banana': 10, 'apple': 100}

I’m trying to multiply the number of sold fruits with the price of that fruit for every given day by a function like this:

def get_sales(quantity, fruit):
    return price_dict[fruit] * quantity

and then I want to create a new DataFrame with the sales by calling that function, like this:

df_sales = df.apply(lambda x: get_sales(x, x.column)

expecting following outcome:

             banana   apple
2023-01-01   10       300
2023-01-02   80       600

However, I can’t figure out how I can pass the column name into the function. How can I use the name of the column in a dictionary, like in my example?

Asked By: Filledille

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Source

Answer 1

For pass columns names here use x.name:

df_sales = df.apply(lambda x: get_sales(x, x.name))

If need multiple by dictionary with keys by columns names simplier is:

df_sales = df.mul(price_dict)
#df_sales = df * price_dict
print (df_sales)
   banana  apple
0      10    300
1      80    600

Answered By: jezrael

Python Pandas: pass column name as argument inte function

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