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[modified] functional.remove renamed to functional.remove_if, moved functional.group_by, more documentation added

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Max Cahill 2020-05-12 09:42:06 +10:00
parent 2d24d8e913
commit e6a59460bd
1 changed files with 21 additions and 16 deletions
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37
functional.lua
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@ -70,6 +70,7 @@ function functional.remap(t, f)
end end
--filters a sequence --filters a sequence
-- returns a table containing items where f(v) returns truthy
function functional.filter(t, f) function functional.filter(t, f)
local r = {} local r = {}
for i,v in ipairs(t) do for i,v in ipairs(t) do
@ -80,8 +81,10 @@ function functional.filter(t, f)
return r return r
end end
-- inverse of filter - returns a table containing items where f(v) returns false. -- complement of filter
function functional.remove(t, f) -- returns a table containing items where f(v) returns falsey
-- nil results are included so that this is an exact complement of filter; consider using partition if you need both!
function functional.remove_if(t, f)
local r = {} local r = {}
for i, v in ipairs(t) do for i, v in ipairs(t) do
if not f(v, i) then if not f(v, i) then
@ -91,7 +94,8 @@ function functional.remove(t, f)
return r return r
end end
--partitions a sequence based on filter criteria --partitions a sequence into two, based on filter criteria
--simultaneous filter and remove_if
function functional.partition(t, f) function functional.partition(t, f)
local a = {} local a = {}
local b = {} local b = {}
@ -105,6 +109,20 @@ function functional.partition(t, f)
return a, b return a, b
end end
-- returns a table where the elements in t are grouped into sequential tables by the result of f on each element.
-- more general than partition, but requires you to know your groups ahead of time (or use numeric grouping) if you want to avoid pairs!
function functional.group_by(t, f)
local result = {}
for i, v in ipairs(t) do
local group = f(v)
if result[group] == nil then
result[group] = {}
end
table.insert(result[group], v)
end
return result
end
--zips two sequences together into a new table, based on another function --zips two sequences together into a new table, based on another function
--iteration limited by min(#t1, #t2) --iteration limited by min(#t1, #t2)
--function receives arguments (t1, t2, i) --function receives arguments (t1, t2, i)
@ -274,17 +292,4 @@ function functional.find_match(t, f)
return nil return nil
end end
-- returns a table where the elements in t are grouped by the result of f on each element.
function functional.group_by(t, f)
local result = {}
for i, v in ipairs(t) do
local group = f(v)
if result[group] == nil then
result[group] = {}
end
table.insert(result[group], v)
end
return result
end
return functional return functional