基于其他列添加条件列：根据x、y值生成新列z

Hey there! Your requirement is essentially to create a column z that takes the minimum value between x and y — since when x > y you want z=y, otherwise z=x, that's exactly picking the smaller of the two values. Let's cover a few common ways to do this depending on what tool you're using:

1. Using Pandas (Python) #

If you're working with data in Python, Pandas makes this super straightforward. Here's a complete example:

import pandas as pd

# Set up your sample data
df = pd.DataFrame({
    'x': [3, 5, 6, 1, 9],
    'y': [4, 2, 6, 7, 4]
})

# Create the z column by taking the minimum of x and y row-wise
df['z'] = df[['x', 'y']].min(axis=1)

# Print the result
print(df)

Running this will output exactly what you need:

x  y  z
0  3  4  3
1  5  2  2
2  6  6  6
3  1  7  1
4  9  4  4

2. Using Excel/Google Sheets #

For spreadsheet tools, it's even simpler. In the first cell of your z column (say, cell C2 if x is in column A and y in column B), enter the formula:
=MIN(A2,B2)
Then just drag the fill handle down to apply it to all rows — that's it!

3. Using SQL #

If you're working with a database table, you can use either a CASE statement (which works across all SQL dialects) or the LEAST function (supported in most major databases like MySQL, PostgreSQL):

Using CASE statement (universal):

SELECT
    x,
    y,
    CASE
        WHEN x > y THEN y
        ELSE x
    END AS z
FROM your_table;

Using LEAST (shorter, if supported):

SELECT x, y, LEAST(x, y) AS z FROM your_table;

Whichever tool you pick, you'll end up with the desired result:

内容的提问来源于stack exchange，提问作者iGada