Performance deep dive

In this approach, we'll find out how to most efficiently determine if a string is a Pangram in Python.

The approaches page lists three idiomatic approaches to this exercise:

1. Using all() on lowercased letters
2. Using set with issubset()
3. Using set with len()

For our performance investigation, we'll also include a fourth approach that uses a bit field to keep track of used letters.

Benchmarks

To benchmark the approaches, we wrote a small benchmark application using the timeit library.

all:   1.505466179997893e-05
all:   1.6063886400021147e-05  // with sentence.casefold()
set:   1.950172399985604e-06
len:   3.7158977999933994e-06
bit:   8.75982620002469e-06

• The set len() approach is not as fast as the set issubset() approach.
• The all() approach is slower than either set approach. Using casefold was slower than using lower.
• Although the bit field approach may be faster in other languages, it is significantly slower in Python. It is faster than the all() approach, but much slower than either set approach.