Python - how to replace values greater and smaller than a particular value

Question

How can I replace the values of a DataFrame if are smaller or greater than a particular value?

print(df)

name            seq1   seq11
0     seq102    -14     -5.99   
1     seq103    -5.25   -7.94

I want to set the values < than -8.5 to 1 and > than -8.5 to 0.

I tried this but all the values gets zero;

import pandas as pd
df = pd.read_csv('df.csv')
num = df._get_numeric_data() 
num[num < -8.50] = 1
num[num > -8.50] = 0

The desired output should be:

name            seq1   seq11
0     seq102      1       0   
1     seq103      0       0

Thank you

semblable · Accepted Answer · 2021-04-12 22:51:18Z

1

Try

num.iloc[:,1:] = num.iloc[:,1:].applymap(lambda x: 1 if x < -8.50 else 0)

Note that values equal to -8.50 will be set to zero here.

answered Apr 12, 2021 at 22:51

semblable

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Comments

ssnk001 · Accepted Answer · 2021-04-12 22:54:00Z

0

def thresh(x):
    if(x < -8.5):
        return 1
    elif(x > -8.5):
        return 0
    return x

print(df[["seq1", "seq2"]].apply(thresh))

answered Apr 12, 2021 at 22:52

ssnk001

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It's probably more efficient (and less verbose) to do this with a lambda function, especially since you're using apply.

I just assumed that it was strictly less than or strictly greater than, so there would be an elif. I don't think lambda functions can do elif right?

You can do it by inserting another if/else after the else operator, or just by stacking two applymaps.