Performing set difference in polars

anti join

Polars provides a special type of join that lets you retrieve items in dataframe 1 that do not have a match in dataframe 2. This works like set difference in mathematics.

\[ \text{set A} - \text{set B} \]

Below are two dataframes to be joined.

df1

shape: (7, 1)

All_Students
str
"Serena"
"Dan"
"Blair"
"Chuck"
"Nate"
"Jenny"
"Raina"

df2

shape: (4, 1)

Passed_Exam
str
"Dan"
"Raina"
"Blair"
"Jenny"

Get students who failed the exam

To retrieve the names of students who failed the exam from the complete list of students, use the Polars join method as follows.

(df1
 .join(df2, left_on='All_Students', right_on='Passed_Exam', how='anti')
)

shape: (3, 1)

All_Students
str
"Serena"
"Chuck"
"Nate"

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