How do I add a space after a certain amount of numbers?
If i have the number 02920555555 and wanted to add a space after the fifth number only, how would I go about that? Could I do this with a gsub and a regular expression? I would like to put it in a helper:
def area_code(tel)
tel.gsub()
end
Thanks
Just use the insert method:
'02920555555'.insert(5, ' ')
# => "02920 555555"
Use '\& ' as replacement string. (\& represents the matched string)
'02920555555'.gsub(/\d{4}/, '\& ')
# => "0292 0555 555"
UPDATE
to add a space after the 5th number only, use sub instead of gsub:
'02920555555'.sub(/\d{5}/, '\& ')
# => "02920 555555"
or using gsub with the pattern ^... (matches only at the beginning of the input string):
'02920555555'.gsub(/^\d{5}/, '\& ')
# => "02920 555555"
If you don't feel comfortable with regex then you can use the insert method:
'123456789'.insert(5, ' ')
The first parameter for the insert method is the position, (the index at which you want to insert) and second parameter is for the character that you want to insert.
So, our code is saying take number 123456789 and insert space at index 5.
output:
"12345 6789"
'0292055555'.gsub(/(\d{5})(\d*)/, "\\1 \\2")
# => 02920 55555
Related
I have a string in the following form:
'123string89continues...'
What is the most elegant way to replace or trim the leading digits? Note, there can be more or less than 3 digits, but at least one will always be present.
'1string89continues...' # This can happen
'0123456789string89continues...' # This can happen
'string89continues...' # This cannot happen
'123string89continues...'[/\D.*/]
#⇒ "string89continues..."
Try this one
"123asdads".sub(/A\d+/, "")
=> "asdads"
"1asdads".sub(/A\d+/, "")
=> "asdads"
"asdads".sub(/A\d+/, "")
=> "asdads"
You can use slice! to delete a specific portion from a string:
string = '123string89continues...'
string.slice!(/\A\d+/) #=> "123"
string #=> "string89continues..."
I have a Model user with the following method:
def number_with_hyphen
number&.insert(8, "-")
end
When I run it several times in my tests I get the following output:
users(:default).number_with_hyphen
"340909-1234"
(byebug) users(:default).number_with_hyphen
"340909--1234"
(byebug) users(:default).number_with_hyphen
"340909---1234"
(byebug) users(:default).number_with_hyphen
"340909----1234"
It changes the number ?Here are the docs https://apidock.com/ruby/v1_9_3_392/String/insert
When I restructure my method to:
def number_with_hyphen
"#{number}".insert(8, "-") if number
end
If works like expected. The output stays the same!
How would you structure the code, how would you perform the insert?
which method should I use instead. Thanks
If you're using the insert method, which in the documentation explicitly states "modifies str", then you will need to avoid doing this twice, rendering it idempotent, or use another method that doesn't mangle data.
One way is a simple regular expression to extract the components you're interested in, ignoring any dash already present:
def number_with_hyphen
if (m = number.match(/\A(\d{8})\-?(\d+)\z/))
[ m[1], m[2] ].join('-')
else
number
end
end
That ends up being really safe. If modified to accept an argument, you can test this:
number = '123456781234'
number_with_hyphen(number)
# => "12345678-1234"
number
# => "123456781234"
number_with_hyphen(number_with_hyphen(number))
# => "12345678-1234"
number_with_hyphen('1234')
# => "1234"
Calling it twice doesn't mangle anything, and any non-conforming data is sent through as-is.
Do a clone of the string:
"#{number}".clone.insert(8, '-')
I'm trying to display an array of words from a user's post. However the method I'm using treats an apostrophe like whitespace.
<%= var = Post.pluck(:body) %>
<%= var.join.downcase.split(/\W+/) %>
So if the input text was: The baby's foot
it would output the baby s foot,
but it should be the baby's foot.
How do I accomplish that?
Accepted answer is too naïve:
▶ "It’s naïve approach".split(/[^'\w]+/)
#⇒ [
# [0] "It",
# [1] "s",
# [2] "nai",
# [3] "ve",
# [4] "approach"
# ]
this is because nowadays there is almost 2016 and many users might want to use their normal names, like, you know, José Østergaard. Punctuation is not only the apostroph, as you might notice.
▶ "It’s naïve approach".split(/[^'’\p{L}\p{M}]+/)
#⇒ [
# [0] "It’s",
# [1] "naïve",
# [2] "approach"
# ]
Further reading: Character Properties.
Along the lines of mudasobwa's answer, here's what \w and \W bring to the party:
chars = [*' ' .. "\x7e"].join
# => " !\"\#$%&'()*+,-./0123456789:;<=>?#ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~"
That's the usual visible lower-ASCII characters we'd see in code. See the Regexp documentation for more information.
Grabbing the characters that match \w returns:
chars.scan(/\w+/)
# => ["0123456789",
# "ABCDEFGHIJKLMNOPQRSTUVWXYZ",
# "_",
# "abcdefghijklmnopqrstuvwxyz"]
Conversely, grabbing the characters that don't match \w, or that match \W:
chars.scan(/\W+/)
# => [" !\"\#$%&'()*+,-./", ":;<=>?#", "[\\]^", "`", "{|}~"]
\w is defined as [a-zA-Z0-9_] which is not what you want to normally call "word" characters. Instead they're typically the characters we use to define variable names.
If you're dealing with only lower-ASCII characters, use the character-class
[a-zA-Z]
For instance:
chars = [*' ' .. "\x7e"].join
lower_ascii_chars = '[a-zA-Z]'
not_lower_ascii_chars = '[^a-zA-Z]'
chars.scan(/#{lower_ascii_chars}+/)
# => ["ABCDEFGHIJKLMNOPQRSTUVWXYZ", "abcdefghijklmnopqrstuvwxyz"]
chars.scan(/#{not_lower_ascii_chars}+/)
# => [" !\"\#$%&'()*+,-./0123456789:;<=>?#", "[\\]^_`", "{|}~"]
Instead of defining your own, you can take advantage of the POSIX definitions and character properties:
chars.scan(/[[:alpha:]]+/)
# => ["ABCDEFGHIJKLMNOPQRSTUVWXYZ", "abcdefghijklmnopqrstuvwxyz"]
chars.scan(/\p{Alpha}+/)
# => ["ABCDEFGHIJKLMNOPQRSTUVWXYZ", "abcdefghijklmnopqrstuvwxyz"]
Regular expressions always seem like a wonderful new wand to wave when extracting information from a string, but, like the Sorcerer's Apprentice found out, they can create havoc when misused or not understood.
Knowing this should help you write a bit more intelligent patterns. Apply that to what the documentation shows and you should be able to easily figure out a pattern that does what you want.
You can use below RegEx instead of /\W+/
var.join.downcase.split(/[^'\w]+/)
/\W/ refers to all non-word characters, apostrophe is one such non-word character.
To keep the code as close to original intent, we can use /[^'\w]/ - this means that all characters that are not apostrophe and word character.
Running that string through irb with the same split call that you wrote in your comment gets this:
irb(main):008:0> "The baby's foot".split(/\W+/)
=> ["The", "baby", "s", "foot"]
However, if you use split without an explicit delimiter, you get the split you're looking for:
irb(main):009:0> "The baby's foot".split
=> ["The", "baby's", "foot"]
Does that get you what you're looking for?
I am saving a price string to my database in a decimal-type column.
The price comes in like this "$ 123.99" which is fine because I wrote a bit of code to remove the "$ ".
However, I forgot that the price may include a comma, so "$ 1,234.99" breaks my code. How can I also remove the comma?
This is my code to remove dollar sign and space:
def price=(price_str)
write_attribute(:price, price_str.sub("$ ", ""))
# possible code to remove comma also?
end
You can get there two ways easily.
String's delete method is good for removing all occurrences of the target strings:
'$ 1.23'.delete('$ ,') # => "1.23"
'$ 123,456.00'.delete('$ ,') # => "123456.00"
Or, use String's tr method:
'$ 1.23'.tr('$, ', '') # => "1.23"
'$ 123,456.00'.tr('$ ,', '') # => "123456.00"
tr takes a string of characters to search for, and a string of characters used to replace them. Consider it a chain of gsub methods, one for each character.
BUT WAIT! THERE'S MORE! If the replacement string is empty, all characters in the search string will be removed.
Is there a Ruby/Rails function that will strip a string of a certain user-defined character? For example if I wanted to strip my string of quotation marks "... text... "
http://api.rubyonrails.org/classes/ActiveSupport/Multibyte/Chars.html#M000942
I don't know if I'm reinventing the wheel here so if you find a built-in method that does the same, please let me know :-)
I added the following to config/initializers/string.rb , which add the trim, ltrim and rtrim methods to the String class.
# in config/initializers/string.rb
class String
def trim(str=nil)
return self.ltrim(str).rtrim(str)
end
def ltrim(str=nil)
if (!str)
return self.lstrip
else
escape = Regexp.escape(str)
end
return self.gsub(/^#{escape}+/, "")
end
def rtrim(str=nil)
if (!str)
return self.rstrip
else
escape = Regexp.escape(str)
end
return self.gsub(/#{escape}+$/, "")
end
end
and I use it like this:
"... hello ...".trim(".") => " hello "
and
"\"hello\"".trim("\"") => "hello"
I hope this helps :-)
You can use tr with the second argument as a blank string. For example:
%("... text... ").tr('"', '')
would remove all the double quotes.
Although if you are using this function to sanitize your input or output then it will probably not be effective at preventing SQL injection or Cross Site Scripting attacks. For HTML you are better off using the gem sanitize or the view helper function h.
I don't know of one out of the box, but this should do what you want:
class String
def strip_str(str)
gsub(/^#{str}|#{str}$/, '')
end
end
a = '"Hey, there are some extraneous quotes in this here "String"."'
puts a.strip_str('"') # -> Hey, there are some extraneous quotes in this here "String".
You could use String#gsub:
%("... text... ").gsub(/\A"+|"+\Z/,'')
class String
# Treats str as array of char
def stripc(str)
out = self.dup
while str.each_byte.any?{|c| c == out[0]}
out.slice! 0
end
while str.each_byte.any?{|c| c == out[-1]}
out.slice! -1
end
out
end
end
Chuck's answer needs some + signs if you want to remove all extra instances of his string pattern. And it doesn't work if you want to remove any of a set of characters that might appear in any order.
For instance, if we want a string to not end with any of the following: a, b, c, and our string is fooabacab, we need something stronger like the code I've supplied above.