Creating new Pandas column based on conditions, but the values do not generate

You can use numpy.select():

df['col']=np.select([df.x.eq(1),df.x.eq(2),df.x.eq(3)],['small','medium','large'],\
                                                                  'something')

you can replace 'something' with the value which should appear when the conditions are not met.

print(df)

   x    size
0  1   small
1  2  medium
2  3   large

You can try more simple version:

import pandas as pd
import numpy as np

df = pd.read_csv('blah.csv')

def size(x):
    if x == 1:
        return 'Small'
    if x == 2:
        return 'Medium'
    if x == 3:
        return 'Large'
    return -99 

# maybe your row type is"string"
df['size'] = df['rQ7'].apply (lambda x: size(int(x)))