Mapreduce Use Case for N-Gram Statistics 1


In this post we will provide solution to famous N-Grams calculator in Mapreduce Programming. Mapreduce Use case for N-Gram Statistics.

N-Gram:

In the fields of computational linguistics and probability, an n-gram is a contiguous sequence of n items from a given sequence of text or speech. The items can be phonemes, syllables, letters, words or base pairs according to the application. The n-grams typically are collected from a text or speech corpus.
An n-gram of size 1 is referred to as a “unigram”; size 2 is a “bigram” (or, less commonly, a “digram”); size 3 is a “trigram”. Larger sizes are sometimes referred to by the value of n, e.g., “four-gram”, “five-gram”,
and so on.
If we are to implement n-gram statistics over the text corpus of all literature collections in digital libraries in MR, how would the Key-value spaces behave?

with n value as 2, the output is

Solution:

Below is the Mapreduce program which can be used to calculate the N-Grams. Here in this program, N can be passed dynamically via command line arguments.