word_freq.lua in Lua

A word-frequency table from gmatch, a tally table, and one sort.

-- Count word frequencies in a passage and chart the leaders.

local passage = "the rain in maine falls mainly on the plain and "
  .. "the rain stays on the plain"

-- Tally every word with gmatch; missing keys start at zero.
local counts = {}
for word in passage:gmatch("%a+") do
  counts[word] = (counts[word] or 0) + 1
end

-- Move to an array and sort: count descending, ties by word.
local ranked = {}
for word, n in pairs(counts) do
  ranked[#ranked + 1] = { word = word, n = n }
end
table.sort(ranked, function(a, b)
  if a.n ~= b.n then return a.n > b.n end
  return a.word < b.word
end)

print(#ranked .. " distinct words")
print("word    ct bar")
for _, entry in ipairs(ranked) do
  print(string.format("%-7s %2d %s",
    entry.word, entry.n, string.rep("#", entry.n)))
end

How it works

1. gmatch("%a+") iterates the words; or 0 seeds the tally.
2. Pairs move into an array so table.sort can rank them.
3. string.rep("#", n) draws each word's bar.

Keywords and builtins used here

• do
• end
• for
• function
• gmatch
• if
• in
• ipairs
• local
• pairs
• print
• return
• then

The run, in numbers

Lines

27

Characters to type

768

Tokens

167

Three-star pace

65 tpm

At the three-star pace of 65 tokens a minute, this run takes about 154 seconds.

Type this snippet

Step 1 of 3 in Encore, step 25 of 27 in Language basics.

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