Penlight

• Index

Contents

• Functions

Modules

• pl
• pl.Date
• pl.List
• pl.Map
• pl.MultiMap
• pl.OrderedMap
• pl.Set
• pl.app
• pl.array2d
• pl.class
• pl.comprehension
• pl.config
• pl.data
• pl.dir
• pl.file
• pl.func
• pl.input
• pl.lapp
• pl.lexer
• pl.luabalanced
• pl.operator
• pl.path
• pl.permute
• pl.pretty
• pl.seq
• pl.sip
• pl.strict
• pl.stringio
• pl.stringx
• pl.tablex
• pl.template
• pl.test
• pl.text
• pl.utils
• pl.xml

Topics

• 01-introduction.md
• 02-arrays.md
• 03-strings.md
• 04-paths.md
• 05-dates.md
• 06-data.md
• 07-functional.md
• 08-additional.md
• 09-discussion.md

Examples

• seesubst.lua
• sipscan.lua
• symbols.lua
• test-cmp.lua
• test-data.lua
• test-listcallbacks.lua
• test-pretty.lua
• test-symbols.lua
• testapp.lua
• testclone.lua
• testconfig.lua
• testglobal.lua
• testinputfields.lua
• testinputfields2.lua
• testxml.lua
• which.lua

Module pl.seq

Manipulating iterators as sequences.

See The Guide

Dependencies: pl.utils , debug

Functions

matching (s)	given a string, return a function(y) which matches y against the string.
list (t)	sequence adaptor for a table.
keys (t)	return the keys of the table.
range (start, finish)	create an iterator over a numerical range.
minmax (iter)	return the minimum and the maximum value of the sequence.
sum (iter, fn)	return the sum and element count of the sequence.
copy (iter)	create a table from the sequence.
copy2 (iter, i1, i2)	create a table of pairs from the double-valued sequence.
copy_tuples (iter)	create a table of ‘tuples’ from a multi-valued sequence.
random (n, l, u)	return an iterator of random numbers.
sort (iter, comp)	return an iterator to the sorted elements of a sequence.
zip (iter1, iter2)	return an iterator which returns elements of two sequences.
count_map (iter)	A table where the key/values are the values and value counts of the sequence.
printall (iter, sep, nfields, fmt)	print out a sequence iter with a separator.
map (fn, iter, arg)	return a sequence where every element of a sequence has been transformed by a function.
filter (iter, pred, arg)	filter a sequence using a predicate function
reduce (fun, iter, oldval)	‘reduce’ a sequence using a binary function.
take (iter, n)	take the first n values from the sequence.
skip (iter, n)	skip the first n values of a sequence
enum (iter)	a sequence with a sequence count and the original value.
mapmethod (iter, name, arg1, arg2)	map using a named method over a sequence.
last (iter)	a sequence of (last,current) values from another sequence.
foreach (iter, fn)	call the function on each element of the sequence.
lines (f)	create a wrapped iterator over all lines in the file.

Functions

matching (s)

given a string, return a function(y) which matches y against the string.

Parameters:

• s: a string

list (t)

sequence adaptor for a table. Note that if any generic function is passed a table, it will automatically use seq.list()

Parameters:

• t: a list-like table

Usage:

• sum(list(t)) is the sum of all elements of t

• for x in list(t) do...end

keys (t)

return the keys of the table.

Parameters:

• t: a list-like table

Returns:

iterator over keys

range (start, finish)

create an iterator over a numerical range. Like the standard Python function xrange.

Parameters:

• start: a number
• finish: a number greater than start

minmax (iter)

return the minimum and the maximum value of the sequence.

Parameters:

• iter: a sequence

Returns:

1. minimum value
2. maximum value

sum (iter, fn)

return the sum and element count of the sequence.

Parameters:

• iter: a sequence
• fn: an optional function to apply to the values

copy (iter)

create a table from the sequence. (This will make the result a List.)

Parameters:

• iter: a sequence

Usage:

• copy(list(ls)) is equal to ls

• copy(list {1,2,3}) == List{1,2,3}

Returns:

a List

copy2 (iter, i1, i2)

create a table of pairs from the double-valued sequence.

Parameters:

• iter: a double-valued sequence
• i1: used to capture extra iterator values
• i2: as with pairs & ipairs

Usage:

copy2(ipairs{10,20,30}) == {{1,10},{2,20},{3,30}}

Returns:

a list-like table

copy_tuples (iter)

create a table of ‘tuples’ from a multi-valued sequence. A generalization of copy2 above

Parameters:

• iter: a multiple-valued sequence

Returns:

a list-like table

random (n, l, u)

return an iterator of random numbers.

Parameters:

• n: the length of the sequence
• l: same as the first optional argument to math.random
• u: same as the second optional argument to math.random

Returns:

a sequnce

sort (iter, comp)

return an iterator to the sorted elements of a sequence.

Parameters:

• iter: a sequence
• comp: an optional comparison function (comp(x,y) is true if x < y)

zip (iter1, iter2)

return an iterator which returns elements of two sequences.

Parameters:

• iter1: a sequence
• iter2: a sequence

Usage:

for x,y in seq.zip(ls1,ls2) do....end

count_map (iter)

A table where the key/values are the values and value counts of the sequence. This version works with ‘hashable’ values like strings and numbers.
pl.tablex.count_map is more general.

Parameters:

• iter: a sequence

Returns:

1. a map-like table
2. a table

see also:

pl.tablex.count_map

printall (iter, sep, nfields, fmt)

print out a sequence iter with a separator.

Parameters:

• iter: a sequence
• sep: the separator (default space)
• nfields: maximum number of values per line (default 7)
• fmt: optional format function for each value

map (fn, iter, arg)

return a sequence where every element of a sequence has been transformed by a function. If you don’t supply an argument, then the function will receive both values of a double-valued sequence, otherwise behaves rather like tablex.map.

Parameters:

• fn: a function to apply to elements; may take two arguments
• iter: a sequence of one or two values
• arg: optional argument to pass to function.

filter (iter, pred, arg)

filter a sequence using a predicate function

Parameters:

• iter: a sequence of one or two values
• pred: a boolean function; may take two arguments
• arg: optional argument to pass to function.

reduce (fun, iter, oldval)

‘reduce’ a sequence using a binary function.

Parameters:

• fun: a function of two arguments
• iter: a sequence
• oldval: optional initial value

Usage:

• seq.reduce(operator.add,seq.list{1,2,3,4}) == 10

• seq.reduce('-',{1,2,3,4,5}) == -13

take (iter, n)

take the first n values from the sequence.

Parameters:

• iter: a sequence of one or two values
• n: number of items to take

Returns:

a sequence of at most n items

skip (iter, n)

skip the first n values of a sequence

Parameters:

• iter: a sequence of one or more values
• n: number of items to skip

enum (iter)

a sequence with a sequence count and the original value.
enum(copy(ls)) is a roundabout way of saying ipairs(ls).

Parameters:

• iter: a single or double valued sequence

Returns:

sequence of (i,v), i = 1..n and v is from iter.

mapmethod (iter, name, arg1, arg2)

map using a named method over a sequence.

Parameters:

• iter: a sequence
• name: the method name
• arg1: optional first extra argument
• arg2: optional second extra argument

last (iter)

a sequence of (last,current) values from another sequence. This will return S(i-1),S(i) if given S(i)

Parameters:

• iter: a sequence

foreach (iter, fn)

call the function on each element of the sequence.

Parameters:

• iter: a sequence with up to 3 values
• fn: a function

lines (f)

create a wrapped iterator over all lines in the file.

Parameters:

• f: either a filename or nil (for standard input)

Returns:

a sequence wrapper