Ruby multiple string replacement

Question

str = \"Hello☺ World☹\"

Expected output is:

\"Hello:) World:(\"

I can do this: str.gsub(\"☺\", \":)\").gsu

Answer 1

Late to the party but if you wanted to replace certain chars with one, you could use a regex

string_to_replace.gsub(/_|,| /, '-')

In this example, gsub is replacing underscores(_), commas (,) or ( ) with a dash (-)

Answer 2

Riffing on naren's answer above, I'd go with

tr = {'a' => '1', 'b' => '2', 'z' => '26'}
mystring.gsub(/[#{tr.keys}]/, tr)

So 'zebraazzeebra'.gsub(/[#{tr.keys}]/, tr) returns "26e2r112626ee2r1"

Answer 3

Another simple way, and yet easy to read is the following:

str = '12 ene 2013'
map = {'ene' => 'jan', 'abr'=>'apr', 'dic'=>'dec'}
map.each {|k,v| str.sub!(k,v)}
puts str # '12 jan 2013'

Answer 4

You could do something like this:

replacements = [ ["☺", ":)"], ["☹", ":("] ]
replacements.each {|replacement| str.gsub!(replacement[0], replacement[1])}

There may be a more efficient solution, but this at least makes the code a bit cleaner

Answer 5

Set up a mapping table:

map = {'☺' => ':)', '☹' => ':(' }

Then build a regex:

re = Regexp.new(map.keys.map { |x| Regexp.escape(x) }.join('|'))

And finally, gsub:

s = str.gsub(re, map)

If you're stuck in 1.8 land, then:

s = str.gsub(re) { |m| map[m] }

You need the Regexp.escape in there in case anything you want to replace has a special meaning within a regex. Or, thanks to steenslag, you could use:

re = Regexp.union(map.keys)

and the quoting will be take care of for you.

Answer 6

You can also use tr to replace multiple characters in a string at once,

Eg., replace "h" to "m" and "l" to "t"

"hello".tr("hl", "mt")
 => "metto"

looks simple, neat and faster (not much difference though) than gsub

puts Benchmark.measure {"hello".tr("hl", "mt") }
  0.000000   0.000000   0.000000 (  0.000007)

puts Benchmark.measure{"hello".gsub(/[hl]/, 'h' => 'm', 'l' => 't') }
  0.000000   0.000000   0.000000 (  0.000021)