Multiply dataframe with series having index duplicates and excluding one column-CodePudding

A shortened version of my dataframe looks like this:

df_crop = pd.DataFrame({
    'Name' : ['Crop1', 'Crop1', 'Crop1', 'Crop1', 'Crop2', 'Crop2', 'Crop2', 'Crop2'],
    'Type' : ['Area', 'Diesel', 'Fert', 'Pest', 'Area', 'Diesel', 'Fert', 'Pest'],
    'GHG':   [14.9, 0.0007, 0.145, 0.1611, 2.537, 0.011, 0.1825, 0.115],
    'Acid':  [0.0125, 0.0005, 0.0029, 0.0044, 0.013, 0.00014, 0.0033, 0.0055],
    'Terra Eutro': [0.053, 0.0002, 0.0077, 0.0001, 0.0547, 0.00019, 0.0058, 0.0002]
})

I now need to normalise all values in the dataframe with yield, which is different per crop, but not per Type:

s_yield = pd.Series([0.388, 0.4129], 
                    index=['Crop1', 'Crop2'])

I need to preserve the information in 'Type'. If I try to use .mul() I receive an error due to the duplicated indices: ValueError: cannot reindex from a duplicate axis.

The only other idea I have is using .loc() but I have a lot of columns (16 with values to normalise) and nothing efficient came to mind. Any suggestions?

Edit: The following table might help to show what I try to achieve:

CodePudding user response：

Get the numeric data and multiply using the series

numeric_df = df_crop.select_dtypes('number')
df_crop[numeric_df.columns] = numeric_df.mul(df_crop.Name.map(s_yield), axis=0)

Output

    Name    Type       GHG      Acid  Terra Eutro
0  Crop1    Area  5.781200  0.004850     0.020564
1  Crop1  Diesel  0.000272  0.000194     0.000078
2  Crop1    Fert  0.056260  0.001125     0.002988
3  Crop1    Pest  0.062507  0.001707     0.000039
4  Crop2    Area  1.047527  0.005368     0.022586
5  Crop2  Diesel  0.004542  0.000058     0.000078
6  Crop2    Fert  0.075354  0.001363     0.002395
7  Crop2    Pest  0.047483  0.002271     0.000083

CodePudding user response：

Starting from pandas 0.24.0 you can merge series to a dataframe directly as long as the series is named:

df_merged = df_crop.merge(s_yield.rename('yield'), left_on = 'Name', right_index = True)

then multiply columns as needed.

CodePudding user response：

You can use s_yield.map to extend the Series to the length of the dataframe, and you can use df.select_dtypes to find all the columns of a specific dtype(s) and multiple on them:

cols = df_crop.select_dtypes('number').columns
df_crop[cols] = df_crop[cols].mul(df_crop['Name'].map(s_yield), axis=0)

Output:

>>> df_crop
    Name    Type       GHG      Acid  Terra Eutro
0  Crop1    Area  5.781200  0.004850     0.020564
1  Crop1  Diesel  0.000272  0.000194     0.000078
2  Crop1    Fert  0.056260  0.001125     0.002988
3  Crop1    Pest  0.062507  0.001707     0.000039
4  Crop2    Area  1.047527  0.005368     0.022586
5  Crop2  Diesel  0.004542  0.000058     0.000078
6  Crop2    Fert  0.075354  0.001363     0.002395
7  Crop2    Pest  0.047483  0.002271     0.000083