Set Operations in R and Python. Useful!

Set operations are super useful when data cleaning or testing scripts. They are a must have in any analyst’s (data scientist’s/statistician’s/data wizard’s) toolbox. Here is a quick rundown in both R and python.

Say we have two vectors x and y…

# vector x
x = c(1,2,3,4,5,6)

# vector y
y = c(4,5,6,7,8,9)

What if we ‘combined’ x and y ignoring any duplicate elements? (x \cup y)

# x UNION y
union(x, y)

[1] 1 2 3 4 5 6 7 8 9

What are the common elements in x and y? (x \cap y)

intersect(x, y)

[1] 4 5 6

What elements feature in x but not in y?

# x members not in y

[1] 1 2 3

What elements feature in y but not in x?

# y members not in x

[1] 7 8 9

How might we visualise all this?

Venn Diagram
Venn Diagram

What about python? In standard python there exists a module called ‘sets’ that allows for the creation of a ‘Set’ object from a python list. The Set object has methods that provide the same functionality as the R functions above.