Module pl.seq

Manipulating iterators as sequences.

See The Guide

Dependencies: pl.utils, pl.types, 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) Makes 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 an arbitrary 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

Returns:

    a List

Usage:

  • copy(list(ls)) is equal to ls
  • copy(list {1,2,3}) == List{1,2,3}
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

Returns:

    a list-like table

Usage:

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

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 func 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, file-like object, or ‘STDIN’ (for standard input)
  • ... for Lua 5.2 only, optional format specifiers, as in io.read.

Returns:

    a sequence wrapper
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