I have a df with the following values:
| id | Count | Exposure | pct_affected |
|---|---|---|---|
| 104 | 4 | 150,000 | 1.2 |
| 104 | 0 | 150,000 | 1.2 |
When I merged my 2 dataframes, the values from one carried onto the other. I need to set both columns Exposure & pct_affected to 0, when count = 0. Otherwise they retain their values.
I tried the mask option & that doesn't work. Thanks for your help.
You can use Numpy's np.where() to check if Count==0 and set the value of each column to 0 or to keep the original.
Full code (including importing libraries and data):
# Import libraries import numpy as np import pandas as pd # Add data to a DataFrame df = pd.DataFrame({'id':[104, 104], 'Count':[4, 0], 'Exposure':[150000, 150000], 'pct_affected':[1.2, 1.2]}).set_index("id") # Define list of columns to set 0 if Count==0 lst_cols_to_set_to_0 = ["Exposure", "pct_affected"] # If Count==0, set value to 0, else keep original value for c in lst_cols_to_set_to_0: df[c] = np.where( df["Count"] == 0, # check 0, # if check true, set to 0 df[c] # if check false, keep original ) a = {'id':[104, 104], 'count':[4, 0], 'exposure':[150000, 150000], 'pct affected':[1.2, 1.2]}
b = pd.DataFrame(a)
b.loc[b['count'] == 0, ['exposure', 'pct affected']] = 0
print(b)
| id | count | exposure | pct affected |
|---|---|---|---|
| 104 | 4 | 150000 | 1.2 |
| 104 | 0 | 0 | 0.0 |
