|
instance methods
|
|
collect
|
enumObj.collect {| obj | block }
-> anArray
|
|
Returns a new array with the results of running block once for every
element in enumObj.
(1..4).collect {|i| i*i }
|
» |
[1, 4, 9, 16]
|
(1..4).collect { "cat" }
|
» |
["cat", "cat", "cat", "cat"]
|
|
|
detect
|
enumObj.detect {| obj | block }
-> anObject or nil
|
|
Passes each entry in enumObj to block. Returns the first for
which block is not false. Returns nil
if no object matches.
(1..10).detect {|i| i % 5 == 0 and i % 7 == 0 }
|
» |
nil
|
(1..100).detect {|i| i % 5 == 0 and i % 7 == 0 }
|
» |
35
|
|
|
each_with_index
|
enumObj.each_with_index
{| obj, i | block }
-> nil
|
|
Calls block with two arguments, the item and its index,
for each item in enumObj.
hash = Hash.new
|
%w(cat dog wombat).each_with_index {|item, index|
|
hash[item] = index
|
}
|
hash
|
» |
{"cat"=>0, "wombat"=>2, "dog"=>1}
|
|
|
entries
|
enumObj.entries -> anArray
|
|
Synonym for
Enumerable#to_a
.
|
|
find
|
enumObj.find {| obj | block }
-> anObject or nil
|
|
Synonym for
Enumerable#detect
.
|
|
find_all
|
enumObj.find_all {| obj | block }
-> anArray
|
|
Returns an array containing all elements of enumObj for which
block is not false (see also
Enumerable#reject
).
(1..10).find_all {|i| i % 3 == 0 }
|
» |
[3, 6, 9]
|
|
|
grep
|
enumObj.grep( pattern ) -> anArray
enumObj.grep( pattern ) {| obj | block }
-> anArray
|
|
Returns an array of every element in enumObj for which
Pattern === element. If the optional block is
supplied, each matching element is passed to it, and the block's
result is stored in the output array.
(1..100).grep 38..44
|
» |
[38, 39, 40, 41, 42, 43, 44]
|
c = IO.constants
|
c.grep(/SEEK/)
|
» |
["SEEK_END", "SEEK_CUR", "SEEK_SET"]
|
res = c.grep(/SEEK/) {|v| IO.const_get(v) }
|
res
|
» |
[2, 1, 0]
|
|
|
include?
|
enumObj.include?( anObject )
-> true or false
|
|
Returns true if any member of enumObj equals
anObject. Equality is tested using ==.
IO.constants.include? "SEEK_SET"
|
» |
true
|
IO.constants.include? "SEEK_NO_FURTHER"
|
» |
false
|
|
|
map
|
enumObj.map {| obj | block }
-> anArray
|
|
Synonym for
Enumerable#collect
.
|
|
max
|
enumObj.max -> anObject
enumObj.max {| a,b | block }
-> anObject
|
|
Returns the object in enumObj with the maximum value. The first
form assumes all objects implement Comparable; the second
uses the block to return a <=> b.
a = %w(albatross dog horse)
|
a.max
|
» |
"horse"
|
a.max {|a,b| a.length <=> b.length }
|
» |
"albatross"
|
|
|
member?
|
enumObj.member?( anObject ) -> true or false
|
|
Synonym for
Enumerable#include?
.
|
|
min
|
enumObj.min -> anObject
enumObj.min {| a,b | block }
-> anObject
|
|
Returns the object in enumObj with the minimum value. The first
form assumes all objects implement Comparable; the second
uses the block to return a <=> b.
a = %w(albatross dog horse)
|
a.min
|
» |
"albatross"
|
a.min {|a,b| a.length <=> b.length }
|
» |
"dog"
|
|
|
reject
|
enumObj.reject {| obj | block }
-> anArray
|
|
Returns an array for all elements of enumObj for which
block is false (see also
Enumerable#find_all
).
(1..10).reject {|i| i % 3 == 0 }
|
» |
[1, 2, 4, 5, 7, 8, 10]
|
|
|
select
|
enumObj.select {| obj | block }
-> anArray
|
|
Synonym for
Enumerable#find_all
.
|
|
sort
|
enumObj.sort -> anArray
enumObj.sort {| a, b | block }
-> anArray
|
|
Returns an array containing the items in enumObj sorted, either
according to their own <=> method, or by using the
results of the supplied block. The block should return -1, 0, or
+1 depending on the comparison between a and b.
%w(rhea kea flea).sort
|
» |
["flea", "kea", "rhea"]
|
(1..10).sort {|a,b| b <=> a}
|
» |
[10, 9, 8, 7, 6, 5, 4, 3, 2, 1]
|
The following code sorts some files on modification time.
files = Dir["*"]
|
sorted = files.sort {|a,b| File.new(a).mtime <=> File.new(b).mtime}
|
sorted
|
» |
["mon", "tues", "wed", "thurs"]
|
This sort is inefficient: it generates two new File objects
during every comparison. A slightly better technique is to use
the
Kernel#test
method to generate the modification times
directly.
files = Dir["*"]
|
sorted = files.sort { |a,b|
|
test(?M, a) <=> test(?M, b)
|
}
|
sorted
|
» |
["mon", "tues", "wed", "thurs"]
|
This still generates many unnecessary Time objects.
A more efficient technique is to cache
the sort keys (modification times in this case) before the sort.
Perl users often call this approach a Schwartzian Transform,
after Randal Schwartz. We construct a temporary array,
where each element is an array containing our sort key along
with the filename. We sort this array, and then extract the
filename from the result.
sorted = Dir["*"].collect { |f|
|
[test(?M, f), f]
|
}.sort.collect { |f| f[1] }
|
sorted
|
» |
["mon", "tues", "wed", "thurs"]
|
|
|
to_a
|
enumObj.to_a -> anArray
|
|
Returns an array containing the items in enumObj.
(1..7).to_a
|
» |
[1, 2, 3, 4, 5, 6, 7]
|
{ 'a'=>1, 'b'=>2, 'c'=>3 }.to_a
|
» |
[["a", 1], ["b", 2], ["c", 3]]
|
|
