@@ -309,7 +309,7 @@ i*(t+9-g)/8,4-a+b
309309```
310310
311311* ` index ` method returns matching position (starts at 0) and nil if not found
312- * supports both string and regex
312+ * supports both string and regexp
313313 * optional 2nd argument allows to specify offset to start searching
314314* See [ ruby-doc: index] ( https://ruby-doc.org/core-2.5.0/String.html#method-i-index ) for details
315315
@@ -321,7 +321,7 @@ i*(t+9-g)/8,4-a+b
321321$ ruby -ne ' print if $_.index("a+b")==0'
322322a+b,pi=3.14,5e12
323323
324- $ # passing regex
324+ $ # passing regexp
325325$ ruby -ne ' print if $_.index(/[+*]/)<5'
326326a+b,pi=3.14,5e12
327327i* (t+9-g)/8,4-a+b
924924## <a name =" ruby-regular-expressions " ></a >Ruby regular expressions
925925
926926* assuming that you are already familiar with basics of regular expressions
927- * if not, see [ Ruby Regular Expressions tutorial ] ( https://github .com/learnbyexample/Ruby_Scripting/blob/master/chapters/Regular_expressions.md )
927+ * if not, check out [ Ruby Regexp ] ( https://leanpub .com/rubyregexp ) ebook - step by step guide from beginner to advanced levels
928928* examples/descriptions based only on ASCII encoding
929929* See [ ruby-doc: Regexp] ( https://ruby-doc.org/core-2.5.0/Regexp.html ) for syntax and feature details
930- * See [ rexegg ruby] ( https://www.rexegg.com/regex-ruby.html ) for a bit of ruby regex history and differences with other regex engines
930+ * See [ rexegg ruby] ( https://www.rexegg.com/regex-ruby.html ) for a bit of ruby regexp history and differences with other regexp engines
931931
932932<br >
933933
@@ -1397,7 +1397,7 @@ $ s='a+b' ruby -ne 'print if /#{Regexp.escape(ENV["s"])}/' eqns.txt
13971397a+b,pi= 3.14,5e12
13981398i* (t+9-g)/8,4-a+b
13991399
1400- $ # use regex as needed around variable content, for ex: end of line anchor
1400+ $ # use regexp as needed around variable content, for ex: end of line anchor
14011401$ ruby -p e ' BEGIN{s="a+b"}; sub(/#{Regexp.escape(s)}$/, "a**b")'
14021402a= b,a-b= c,c* d
14031403a+b,pi= 3.14,5e12
@@ -2153,15 +2153,30 @@ $ ruby -e 'books=%w[Elantris Martian Dune Alchemist]
21532153
21542154# ### <a name="filtering"></a>Filtering
21552155
2156- * based on a condition
2156+ * based on regexp
21572157
2158- ` ` `
2159- $ # based on regex matching
2158+ ` ` `
21602159$ s= ' foo:123:bar:baz'
2161- $ echo " $s " | ruby -F: -lane ' print $F.select { |s| s =~ /[a-z]/ } * ":"'
2160+ $ echo " $s " | ruby -F: -lane ' print $F.grep( /[a-z]/) * ":"'
21622161foo:bar:baz
21632162
2163+ $ words= ' tryst fun glyph pity why'
2164+ $ echo " $words " | ruby -lane ' puts $F.grep(/[a-g]/)'
2165+ fun
2166+ glyph
2167+
2168+ $ # grep_v inverts the selection
2169+ $ echo " $words " | ruby -lane ' puts $F.grep_v(/[aeiou]/)'
2170+ tryst
2171+ glyph
2172+ why
2173+ ` ` `
2174+
2175+ * use ` ` or ` ` for generic conditions
2176+
2177+ ` ` `
21642178$ # to get index instead of matches
2179+ $ s= ' foo:123:bar:baz'
21652180$ echo " $s " | ruby -F: -lane ' print $F.each_index.select{|i| $F[i] =~ /[a-z]/}'
21662181[0, 2, 3]
21672182
@@ -2171,10 +2186,9 @@ $ echo "$s" | ruby -lane 'print $F.select { |s| s.to_i < 100 } * " "'
2171218623 -983 5
21722187
21732188$ # filters only those elements with successful substitution
2189+ $ # for opposite, either use negated condition or use reject instead of select
21742190$ echo " $s " | ruby -lane ' print $F.select { |s| s.sub!(/3/, "E") } * " "'
217521912E -98E
2176-
2177- $ # for opposite, either use negated condition or use reject instead of select
21782192` ` `
21792193
21802194* random element(s)
@@ -2423,7 +2437,7 @@ $ # specify a negative count to preserve trailing empty fields
24232437$ echo ' :123::' | ruby -lne ' print $_.split(/:/, -1) * ","'
24242438,123,,
24252439
2426- $ # use string argument for fixed-string split instead of regex
2440+ $ # use string argument for fixed-string split instead of regexp
24272441$ echo ' foo**123**baz' | ruby -lne ' print $_.split("**") * ":"'
24282442foo:123:baz
24292443
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