Using dicts to look up values for DataFrame variables

Question

I have a pandas DataFrame with columns Teacher_ID and Student_ID. I also have dicts for each, TDict and SDict, giving, say, the grade in which each teacher teaches and the grade each student is enrolled in, with their ID numbers as the keys.

I want to create a new column in my DataFrame referencing the information in the dicts. But when I try to create a column with a formula something like TDict[Teacher_ID] + SDict[Student_ID], I get an error message telling me that "'Series' objects are mutable, thus they cannot be hashed."

What's the approved way around this? Do I have to copy the ID's into new columns, replace the values in those columns with the dict values, and then work from there? I'm guessing there's a better way....

Answer 1

If I understand you correctly then you can simply call map :

df['Teaching_grade'] = df['Teacher_ID'].map(TDict)
df['Student_grade'] = df['Student_ID'].map(SDict)

This will perform the lookup and assign the value to the new column