How do I convert a Pandas string column into specific numbers without using a loop?

Question

I have a column of strings that I’d like to convert into specific numbers. My current approach involves using a for loop, but I feel that’s not how Pandas was designed to be used. Could someone suggest a more elegant solution that is applicable to more than one column?

Here is my code –

import pandas as pd
data = [['mechanical@engineer', 'field engineer'], ['field engineer', 'lab_scientist'],
        ['lab_scientist', 'mechanical@engineer'], ['field engineer', 'mechanical@engineer'],
        ['lab_scientist','mechanical@engineer']]# Create the pandas DataFrame
df = pd.DataFrame(data, columns=['Job1', 'Job2'])
for index, row in df.iterrows():
    if row['Job1']=="mechanical@engineer":
        row['Job1'] = 0
    elif row['Job1']=="field engineer":
        row['Job1'] = 1
    elif row['Job1'] == "lab_scientist":
        row['Job1'] = 2
print(df.head())

Asked By: desert_ranger

||

Source

Answer 1

Looks like you just need a map:

role_to_code = {"mechanical@engineer": 0, "field engineer": 1, "lab_scientist": 2}

df.Job1.map(role_to_code)
#0    0
#1    1
#2    2
#3    1
#4    2
#Name: Job1, dtype: int64

Answered By: Psidom

Answer 2

why dont you use replace function instead of your for loop?

mapping = {'mechanical@engineer': 0, 'field engineer': 1, 'lab_scientist': 2}

df = df.replace(mapping)

print(df.head())

output would be:

   Job1  Job2
0     0     1
1     1     2
2     2     0
3     1     0
4     2     0

Answered By: Phoenix

How do I convert a Pandas string column into specific numbers without using a loop?

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