CODEWITHSUNDEEP
sqlsqlite
user1956609
user1956609

Reputation: 2202

Finding most common words in a column using sqlite?

I have data that looks like this:

            movie_id    comment
            1           tom cruise is great
            1           great action movie
            2           got teary eyed
            2           great cast
            1           tom cruise is hott

I'd like a function that returns the most common words in the comments, based on what movie_id I select. So if I'm querying movie_id=1, I'd get:

            tom, 2
            cruise, 2
            is, 2
            great, 2
            hott, 1
            action, 1
            movie, 1

While if I query movie_id=2, I'd get:

            got, 1
            teary, 1
            eyed, 1
            great, 1
            cast, 1

I saw some solutions using tsql, but I've never used that before and didn't understand the code. Looking for a way to do this in sqlite3.

Upvotes: 3

Views: 2159

Answers (2)

oxuser
oxuser

Reputation: 1327

This a hack, but you can also use SQLite's Table-valued Functions to solve this:

select value from (
    select
        '["' || replace(trim(title), '"', '') || '"]' as arr
    from story limit 2500000
    ) e, json_each(e.arr)

Watch out though - you might notice that you have a lot of characters in your column that may break JSON parsing and throw a JSON parsing error.

In that case, you might have to remove some control characters:

select value from (select
'["' || replace(replace(replace(replace(replace(replace(trim(title), '"', ''), CHAR(10), ""), CHAR(13), ''), "  ", ""), "\", ""), ' ', '","') 
|| '"]' as arr
from your_table limit 2500000
) e, json_each(e.arr)

To make it easier to debug, you can use a combo of limit and offset (eg. limit 1000000 offset 2200000) to help you find the problem rows and then replace that character with a an empty string.

Upvotes: 0

Gordon Linoff
Gordon Linoff

Reputation: 1270713

You can do this with a really ugly query.

select word, count(*) from (
select (case when instr(substr(m.comments, nums.n+1), ' ') then substr(m.comments, nums.n+1)
             else substr(m.comments, nums.n+1, instr(substr(m.comments, nums.n+1), ' ') - 1)
        end) as word
from (select ' '||comments as comments
      from m
     )m cross join
     (select 1 as n union all select 2 union all select 3
     ) nums
where substr(m.comments, nums.n, 1) = ' ' and substr(m.comments, nums.n, 1) <> ' '
) w
group by word
order by count(*) desc

This is untested. The inner query needs a list of numbers (limited to just 3 here; you can see how to add more). It then checks to see if a word starts at position n+1. A word starts after a space, so I put a space at the beginning of the comments.

Then it pulls the word out, for aggregation purposes.

Upvotes: 4

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