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Name	Size	Permission
Enumerator	[ DIR ]	drwxr-xr-x
all%3f-i.yaml	856 B	-rw-r--r--
any%3f-i.yaml	877 B	-rw-r--r--
cdesc-Enumerable.yaml	2.9 KB	-rw-r--r--
collect-i.yaml	609 B	-rw-r--r--
count-i.yaml	815 B	-rw-r--r--
cycle-i.yaml	896 B	-rw-r--r--
detect-i.yaml	732 B	-rw-r--r--
drop-i.yaml	435 B	-rw-r--r--
drop_while-i.yaml	539 B	-rw-r--r--
each_cons-i.yaml	633 B	-rw-r--r--
each_slice-i.yaml	563 B	-rw-r--r--
each_with_index-i.yaml	609 B	-rw-r--r--
entries-i.yaml	546 B	-rw-r--r--
enum_cons-i.yaml	633 B	-rw-r--r--
enum_slice-i.yaml	563 B	-rw-r--r--
enum_with_index-i.yaml	609 B	-rw-r--r--
find-i.yaml	728 B	-rw-r--r--
find_all-i.yaml	541 B	-rw-r--r--
find_index-i.yaml	769 B	-rw-r--r--
first-i.yaml	455 B	-rw-r--r--
grep-i.yaml	845 B	-rw-r--r--
group_by-i.yaml	519 B	-rw-r--r--
include%3f-i.yaml	585 B	-rw-r--r--
inject-i.yaml	209 B	-rw-r--r--
map-i.yaml	601 B	-rw-r--r--
max-i.yaml	678 B	-rw-r--r--
max_by-i.yaml	466 B	-rw-r--r--
member%3f-i.yaml	583 B	-rw-r--r--
min-i.yaml	678 B	-rw-r--r--
min_by-i.yaml	460 B	-rw-r--r--
minmax-i.yaml	787 B	-rw-r--r--
minmax_by-i.yaml	567 B	-rw-r--r--
none%3f-i.yaml	895 B	-rw-r--r--
one%3f-i.yaml	893 B	-rw-r--r--
partition-i.yaml	537 B	-rw-r--r--
reduce-i.yaml	2.05 KB	-rw-r--r--
reject-i.yaml	485 B	-rw-r--r--
reverse_each-i.yaml	297 B	-rw-r--r--
select-i.yaml	537 B	-rw-r--r--
sort-i.yaml	926 B	-rw-r--r--
sort_by-i.yaml	3.16 KB	-rw-r--r--
take-i.yaml	398 B	-rw-r--r--
take_while-i.yaml	509 B	-rw-r--r--
to_a-i.yaml	540 B	-rw-r--r--
to_set-i.yaml	348 B	-rw-r--r--
zip-i.yaml	1.01 KB	-rw-r--r--

Code Editor : sort_by-i.yaml

--- !ruby/object:RI::MethodDescription 
aliases: []

block_params: 
comment: 
- !ruby/struct:SM::Flow::P 
 body: Sorts enum using a set of keys generated by mapping the values in enum through the given block.
- !ruby/struct:SM::Flow::VERB 
 body: " %w{ apple pear fig }.sort_by {|word| word.length}\n #=&gt; [&quot;fig&quot;, &quot;pear&quot;, &quot;apple&quot;]\n"
- !ruby/struct:SM::Flow::P 
 body: The current implementation of <tt>sort_by</tt> generates an array of tuples containing the original collection element and the mapped value. This makes <tt>sort_by</tt> fairly expensive when the keysets are simple
- !ruby/struct:SM::Flow::VERB 
 body: " require 'benchmark'\n include Benchmark\n\n a = (1..100000).map {rand(100000)}\n\n bm(10) do |b|\n b.report(&quot;Sort&quot;) { a.sort }\n b.report(&quot;Sort by&quot;) { a.sort_by {|a| a} }\n end\n"
- !ruby/struct:SM::Flow::P 
 body: produces:
- !ruby/struct:SM::Flow::VERB 
 body: " user system total real\n Sort 0.180000 0.000000 0.180000 ( 0.175469)\n Sort by 1.980000 0.040000 2.020000 ( 2.013586)\n"
- !ruby/struct:SM::Flow::P 
 body: However, consider the case where comparing the keys is a non-trivial operation. The following code sorts some files on modification time using the basic <tt>sort</tt> method.
- !ruby/struct:SM::Flow::VERB 
 body: " files = Dir[&quot;*&quot;]\n sorted = files.sort {|a,b| File.new(a).mtime &lt;=&gt; File.new(b).mtime}\n sorted #=&gt; [&quot;mon&quot;, &quot;tues&quot;, &quot;wed&quot;, &quot;thurs&quot;]\n"
- !ruby/struct:SM::Flow::P 
 body: "This sort is inefficient: it generates two new <tt>File</tt> objects during every comparison. A slightly better technique is to use the <tt>Kernel#test</tt> method to generate the modification times directly."
- !ruby/struct:SM::Flow::VERB 
 body: " files = Dir[&quot;*&quot;]\n sorted = files.sort { |a,b|\n test(?M, a) &lt;=&gt; test(?M, b)\n }\n sorted #=&gt; [&quot;mon&quot;, &quot;tues&quot;, &quot;wed&quot;, &quot;thurs&quot;]\n"
- !ruby/struct:SM::Flow::P 
 body: This still generates many unnecessary <tt>Time</tt> 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.
- !ruby/struct:SM::Flow::VERB 
 body: " sorted = Dir[&quot;*&quot;].collect { |f|\n [test(?M, f), f]\n }.sort.collect { |f| f[1] }\n sorted #=&gt; [&quot;mon&quot;, &quot;tues&quot;, &quot;wed&quot;, &quot;thurs&quot;]\n"
- !ruby/struct:SM::Flow::P 
 body: This is exactly what <tt>sort_by</tt> does internally.
- !ruby/struct:SM::Flow::VERB 
 body: " sorted = Dir[&quot;*&quot;].sort_by {|f| test(?M, f)}\n sorted #=&gt; [&quot;mon&quot;, &quot;tues&quot;, &quot;wed&quot;, &quot;thurs&quot;]\n"
full_name: Enumerable#sort_by
is_singleton: false
name: sort_by
params: |
 enum.sort_by {| obj | block } => array

visibility: public

${this.title}

Code Editor : sort_by-i.yaml