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 |
» |
{"dog"=>1, "wombat"=>2, "cat"=>0} |
| 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]] |
|