How to Delete Specific Characters from a String in Ruby

How to delete specific characters from a string in Ruby?

Do as below using String#tr :

 "((String1))".tr('()', '')
 # => "String1"

How to remove characters from String at specific index in Ruby

I think you want this:

>> string = 'Set{[8, 4, "a", 6, 1]}'
=> "Set{[8, 4, \"a\", 6, 1]}"
>> string.gsub('{[', '{').gsub(']}', '}')
=> "Set{8, 4, \"a\", 6, 1}"

If there is any danger that you might see the '{[' or ']}' pattern in the middle of the string and want to preserve it there, and if you are sure of the position relative to the start and end of the string each time, you could do this:

>> string = 'Set{[8, 4, "a", 6, 1]}'
>> chars = string.chars
>> chars.delete_at(4)
>> chars.delete_at(-2)
>> chars.join
=> "Set{8, 4, \"a\", 6, 1}"

Deleting all special characters from a string - ruby

You can do this

a.gsub!(/[^0-9A-Za-z]/, '')

How to Delete Strings that Start with Certain Characters in Ruby

Check if there's a whitespace (\s) before or if it's the start of the string (^).

(?:\s|^)@.*

Live Demo

If you only want to match word characters, then instead of using . you could use \w. Also note that * would still match just "@", so you might want to use + instead to match at least one character.

(?:\s|^)@\w+

Live Demo

Remove substring from the string

You can use the slice method:

a = "foobar"
a.slice! "foo"
=> "foo"
a
=> "bar"

there is a non '!' version as well. More info can be seen in the documentation about other versions as well:
http://www.ruby-doc.org/core/classes/String.html#method-i-slice-21

How to remove strings that end with a particular character in Ruby

You were so close.

email = email.gsub( /.*\.\s*$/ , "")

The difference lies in the fact that you didn't consider the relationship between string of reference and the regex tokens that describe the condition you wish to trigger. Here, you are trying to find a period (\.) which is followed only by whitespace (\s) or the end of the line ($). I would read the regex above as "Any characters of any length followed by a period, followed by any amount of whitespace, followed by the end of the line."

As commenters pointed out, though, there's a simpler way: String#end_with?.

Remove character from string if it starts with that character?

Why not just include the regex in the sub! method?

string.sub!(/^1/, '')

how to delete specific characters in ruby?

Here is a non-Rails approach:

require 'cgi'

str = 'Company "Life"'

puts CGI.unescape_html(str).gsub(/"/, '').gsub(/\s+/, '-').downcase

# => company-life

And a pure regex solution:

puts str.gsub(/&\w+;/, '').gsub(/\s+/, '-').downcase
# => company-life

And if you are inside Rails(thanks to @nzifnab):

str.gsub(/&\w+;/, '').parameterize

How can remove some special character from string of array

The same way you map over the collection, you can iterate it using a block:

["hardware", "computer", "network", "mobile devices"].map do |asset_type|
  asset_type.delete(' ')
            .delete('_')
            .delete('.')
end

Your function could look something like:

def valid_sheet_names
  asset_types = Company.find(@company_id).asset_types.pluck(:name).reject(&:nil?)

  # I'd personally extract normalization to a specific function or module
  asset_types.map do |asset_type|
    asset_type.downcase
              .delete(' ')
              .delete('.')
              .delete('_')
  end
end

You can also use gsub (which supports regular expressions). Though I found delete more explicit when we want to... delete

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