I am trying to read a column in python, and create a new column using python.

import pandas as pd 
df = pd.read_csv (r'C:\Users\User\Documents\Research\seqadv.csv') 
print (df)

df = pd.DataFrame(data={'WT_RESIDUE':['']})
codes = {'ALA':'A', 'ARG':'R', 'ASN':'N', 'ASP':'D', 'CYS':'C', 'GLU':'E', 'GLN':'Q', 'GLY':'G', 'HIS':'H', 'ILE':'I', 'LEU':'L', 'LYS':'K', 'MET':'M', 'PHE':'F', 'PRO':'P', 'SER':'S', 'THR':'T', 'TRP':'W', 'TYR':'Y', 'VAL':'V'}
df['MUTATION_CODE'] = df['WT_RESIDUE'].replace(codes)
df.to_csv (r'C:\Users\User\Documents\Research\output.csv')

I tried this, but it will not create a new column no matter what I do.

I am trying to read a column in python, and create a new column using python.

import pandas as pd 
df = pd.read_csv (r'C:\Users\User\Documents\Research\seqadv.csv') 
print (df)

df = pd.DataFrame(data={'WT_RESIDUE':['']})
codes = {'ALA':'A', 'ARG':'R', 'ASN':'N', 'ASP':'D', 'CYS':'C', 'GLU':'E', 'GLN':'Q', 'GLY':'G', 'HIS':'H', 'ILE':'I', 'LEU':'L', 'LYS':'K', 'MET':'M', 'PHE':'F', 'PRO':'P', 'SER':'S', 'THR':'T', 'TRP':'W', 'TYR':'Y', 'VAL':'V'}
df['MUTATION_CODE'] = df['WT_RESIDUE'].replace(codes)
df.to_csv (r'C:\Users\User\Documents\Research\output.csv')

I tried this, but it will not create a new column no matter what I do.

example