Skip to content

Instantly share code, notes, and snippets.

@andy0130tw
Created May 9, 2018 19:29
Embed
What would you like to do?
FLOLAC 2018 Warm-up Week 2 -- histogram: make a histogram from a list of [0..9]
numOccs :: [Int] -> [Int]
numOccs xs = map (\n -> length $ filter (== n) xs) [0..9]
histogramLine :: [Int] -> Int -> String
histogramLine freqs bl = map (putc . (>= bl)) freqs
where putc cond = if cond then '*' else ' '
histogram :: [Int] -> String
histogram xs = unlines $
(map (histogramLine freqs) (cbTo1 $ maximum freqs)
++ footer)
where labels = "0123456789"
footer = [replicate (length labels) '=', labels]
freqs = numOccs xs
cbTo1 x = reverse [1 .. x]
{-
usage: putStr $ histogram [...]
example:
> histogram [1,4,5,4,6,6,3,4,2,4,9]
*
*
* *
****** *
==========
0123456789
-}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment