I'm attempting to extract population from a JSON response from Wikipedia. Here's an example string...
population_estimate=123,456,789<ref> {{ cite...
...but I'm running into issues due to the commas. Specifically, I'd like to extract the number after the =, but the commas are throwing me off. I had originally had an expression that gets everything until <ref> but sometimes that part doesn't appear within the string.
The answer that worked for me came from #ctwheels:
let regexPopulation = "(?<==)\\d{1,3}(?:,\\d{3})*"
let extractedPopulation = matches(for: regexPopulation, in: String)
Note that I had to add the additional \ due to Swift syntax. Otherwise Xcode kept returning:
Invalid escape sequence in literal
Thanks all!
Related
So I had this code working for a few months already, lets say I have a table called Categories, which has a string column called name, so I receive a string and I want to know if any category was mentioned (a mention occur when the string contains the substring: #name_of_a_category), the approach I follow for this was something like below:
categories.select { |category_i| content_received.downcase.match(/##{category_i.downcase}/)}
That worked pretty well until today suddenly started to receive an exception unmatched close parenthesis, I realized that the categories names can contain special chars so I decided to not consider special chars or spaces anymore (don't want to add restrictions to the user and at the same time don't want to deal with those cases so the policy is just to ignore it).
So the question is there a clean way of removing these special chars (maintaining the #) and matching the string (don't want to modify the data just ignore it while looking for mentions)?
You can also use
prep_content_received = content_received.gsub(/[^\w\s]|_/,'')
p categories.select { |c|
prep_content_received.match?(/\b#{c.gsub(/[^\w\s]|_/, '').strip()}\b/i)
}
See the Ruby demo
Details:
The prep_content_received = content_received.gsub(/[^\w\s]|_/,'') creates a copy of content_received with no special chars and _. Using it once reduced overhead if there are a lot of categories
Then, you iterate over the categories list, and each time check if the prep_content_received matches \b (word boundary) + category with all special chars, _ and leading/trailing whitespace stripped from it + \b in a case insensitive way (see the /i flag, no need to .downcase).
So after looking around I found some answers on the platform but nothing with my specific requirements (maybe I missed something, if so please let me know), and this is how I fix it for my case:
content_received = 'pepe is watching a #comedy :)'
categories = ['comedy :)', 'terror']
temp_content = content_received.downcase
categories.select { |category_i| temp_content.gsub(/[^\sa-zA-Z0-9]/, '#' => '#').match?(/##{category_i.downcase.
gsub(/[^\sa-zA-Z0-9]/, '')}/) }
For the sake of the example, I reduced the categories to a simple array of strings, basically the first gsub, remove any character that is not a letter or a number (any special character) and replace each # with an #, the second gsub is a simpler version of the first one.
You can test the snippet above here
In many other programming languages, there is a function which takes as a parameter a regular expression and returns an array of string values. This is true of Javascript and Ruby. The .match in crystal, however, does 1) not seem to accept the global flag and 2) it does not return an array but rather a struct of type Regex::MatchData. (https://crystal-lang.org/api/0.25.1/Regex/MatchData.html)
As an example the following code:
str = "Happy days"
re = /[a-z]+/i
matches = str.match(re)
puts matches
returns Regex::MatchData("Happy")
I am unsure how to convert this result into a string or why this is not the default as it is in the inspiration language (Ruby). I understand this question probably results from my inexperience dealing with structs and compiled languages but I would appreciate an answer in hopes that it might also help someone else coming from a JS/Ruby background.
What if I want to convert to a string merely the first match?
puts "Happy days"[/[a-z]+/i]?
puts "Happy days".match(/[a-z]+/i).try &.[0]
It will try to match a string against /[a-z]+/i regex and if there is a match, Group 0, i.e. the whole match, will be output. Note that the ? after [...] will make it fail gracefully if there is no match found. If you just use puts "??!!"[/[a-z]+/i], an exception will be thrown.
See this online demo.
If you want the functionality similar to String#scan that returns all matches found in the input, you may use (shortened version only left as per #Amadan's remark):
matches = str.scan(re).map(&.string)
Output of the code above:
["Happy days", "Happy days"]
Note that:
String::scan will return an array of Regex::MatchData for each match.
You can call .string on the match to return the actual matched text.
Actually the posted example returns a #<MatchData "Happy"> in Ruby, which also has no "global" flag – thats what String#scan(Regex) is for as mentioned by others.
If you want only a single match without going through Regex::MatchData, you can use String#[](Regex):
str = "Happy days"
p str[/[a-z]+/i] # => "Happy"
I'm converting a text file to a Tab-Delimited text file, and ran into a bit of a snag. I can get everything I need to work the way I want except for one small part.
One field I'm working with has the home addresses of the subjects as a single entry ("1234 Happy Lane Somewhere, St 12345") and I need each broken down by Street(Tab)City(Tab)State(Tab)Zip. The one part I'm hung up on is the Tab between the State and the Zip.
I've been using input=input.Replace throughout, and it's worked well so far, but I can't think of how to untangle this one. The wildcards I'm used to don't seem to be working, I can't replace ("?? #####") with ("??" + ControlChars.Tab + "#####")...which I honestly didn't expect to work, but it's the only idea on the matter I had.
I've read a bit about using Regex, but have no experience with it, and it seems a bit...overwhelming.
Is Regex my best option for this? If not, are there any other suggestions on solutions I may have missed?
Thanks for your time. :)
EDIT: Here's what I'm using so far. It makes some edits to the line in question, taking care of spaces, commas, and other text I don't need, but I've got nothing for the State/Zip situation; I've a bad habit of wiping something if it doesn't work, but I'll append the last thing I used to the very end, if that'll help.
If input Like "Guar*###/###-####" Then
input = input.Replace("Guar:", "")
input = input.Replace(" ", ControlChars.Tab)
input = input.Replace(",", ControlChars.Tab)
input = "C" + ControlChars.Tab + strAccount + ControlChars.Tab + input
End If
input = System.Text.RegularExpressions.Regex.Replace(" #####", ControlChars.Tab + "#####") <-- Just one example of something that doesn't work.
This is what's written to input in this example
" Guar: LASTNAME,FIRSTNAME 999 E 99TH ST CITY,ST 99999 Tel: 999/999-9999"
And this is what I can get as a result so far
C 99999/9 LASTNAME FIRSTNAME 999 E 99TH ST CITY ST 99999 999/999-9999
With everything being exactly what I need besides the "ST 99999" bit (with actual data obviously omitted for privacy and professional whatnots).
UPDATE: Just when I thought it was all squared away, I've got another snag. The raw data gives me this.
# TERMINOLOGY ######### ##/##/#### # ###.##
And the end result is giving me this, because this is a chunk of data that was just fine as-is...before I removed the Tabs. Now I need a way to replace them after they've been removed, or to omit this small group of code from a document-wide Tab genocide I initiate the code with.
#TERMINOLOGY###########/##/########.##
Would a variant on rgx.Replace work best here? Or can I copy the code to a variable, remove Tabs from the document, then insert the variable without losing the tabs?
I think what you're looking for is
Dim r As New System.Text.RegularExpressions.Regex(" (\d{5})(?!\d)")
Dim input As String = rgx.Replace(input, ControlChars.Tab + "$1")
The first line compiles the regular expression. The \d matches a digit, and the {5}, as you can guess, matches 5 repetitions of the previous atom. The parentheses surrounding the \d{5} is known as a capture group, and is responsible for putting what's captured in a pseudovariable named $1. The (?!\d) is a more advanced concept known as a negative lookahead assertion, and it basically peeks at the next character to check that it's not a digit (because then it could be a 6-or-more digit number, where the first 5 happened to get matched). Another version is
" (\d{5})\b"
where the \b is a word boundary, disallowing alphanumeric characters following the digits.
Is it possible to write a regular expression that matches all strings that does not only contain numbers? If we have these strings:
abc
a4c
4bc
ab4
123
It should match the four first, but not the last one. I have tried fiddling around in RegexBuddy with lookaheads and stuff, but I can't seem to figure it out.
(?!^\d+$)^.+$
This says lookahead for lines that do not contain all digits and match the entire line.
Unless I am missing something, I think the most concise regex is...
/\D/
...or in other words, is there a not-digit in the string?
jjnguy had it correct (if slightly redundant) in an earlier revision.
.*?[^0-9].*
#Chad, your regex,
\b.*[a-zA-Z]+.*\b
should probably allow for non letters (eg, punctuation) even though Svish's examples didn't include one. Svish's primary requirement was: not all be digits.
\b.*[^0-9]+.*\b
Then, you don't need the + in there since all you need is to guarantee 1 non-digit is in there (more might be in there as covered by the .* on the ends).
\b.*[^0-9].*\b
Next, you can do away with the \b on either end since these are unnecessary constraints (invoking reference to alphanum and _).
.*[^0-9].*
Finally, note that this last regex shows that the problem can be solved with just the basics, those basics which have existed for decades (eg, no need for the look-ahead feature). In English, the question was logically equivalent to simply asking that 1 counter-example character be found within a string.
We can test this regex in a browser by copying the following into the location bar, replacing the string "6576576i7567" with whatever you want to test.
javascript:alert(new String("6576576i7567").match(".*[^0-9].*"));
/^\d*[a-z][a-z\d]*$/
Or, case insensitive version:
/^\d*[a-z][a-z\d]*$/i
May be a digit at the beginning, then at least one letter, then letters or digits
Try this:
/^.*\D+.*$/
It returns true if there is any simbol, that is not a number. Works fine with all languages.
Since you said "match", not just validate, the following regex will match correctly
\b.*[a-zA-Z]+.*\b
Passing Tests:
abc
a4c
4bc
ab4
1b1
11b
b11
Failing Tests:
123
if you are trying to match worlds that have at least one letter but they are formed by numbers and letters (or just letters), this is what I have used:
(\d*[a-zA-Z]+\d*)+
If we want to restrict valid characters so that string can be made from a limited set of characters, try this:
(?!^\d+$)^[a-zA-Z0-9_-]{3,}$
or
(?!^\d+$)^[\w-]{3,}$
/\w+/:
Matches any letter, number or underscore. any word character
.*[^0-9]{1,}.*
Works fine for us.
We want to use the used answer, but it's not working within YANG model.
And the one I provided here is easy to understand and it's clear:
start and end could be any chars, but, but there must be at least one NON NUMERICAL characters, which is greatest.
I am using /^[0-9]*$/gm in my JavaScript code to see if string is only numbers. If yes then it should fail otherwise it will return the string.
Below is working code snippet with test cases:
function isValidURL(string) {
var res = string.match(/^[0-9]*$/gm);
if (res == null)
return string;
else
return "fail";
};
var testCase1 = "abc";
console.log(isValidURL(testCase1)); // abc
var testCase2 = "a4c";
console.log(isValidURL(testCase2)); // a4c
var testCase3 = "4bc";
console.log(isValidURL(testCase3)); // 4bc
var testCase4 = "ab4";
console.log(isValidURL(testCase4)); // ab4
var testCase5 = "123"; // fail here
console.log(isValidURL(testCase5));
I had to do something similar in MySQL and the following whilst over simplified seems to have worked for me:
where fieldname regexp ^[a-zA-Z0-9]+$
and fieldname NOT REGEXP ^[0-9]+$
This shows all fields that are alphabetical and alphanumeric but any fields that are just numeric are hidden. This seems to work.
example:
name1 - Displayed
name - Displayed
name2 - Displayed
name3 - Displayed
name4 - Displayed
n4ame - Displayed
324234234 - Not Displayed
I am wanting to create a regular expression for the following scenario:
If a string contains the percentage character (%) then it can only contain the following: %20, and cannot be preceded by another '%'.
So if there was for instance, %25 it would be rejected. For instance, the following string would be valid:
http://www.test.com/?&Name=My%20Name%20Is%20Vader
But these would fail:
http://www.test.com/?&Name=My%20Name%20Is%20VadersAccountant%25
%%%25
Any help would be greatly appreciated,
Kyle
EDIT:
The scenario in a nutshell is that a link is written to an encoded state and then launched via JavaScript. No decoding works. I tried .net decoding and JS decoding, each having the same result - The results stay encoded when executed.
Doesn't require a %:
/^[^%]*(%20[^%]*)*$/
Which language are you using?
Most languages have a Uri Encoder / Decoder function or class.
I would suggest you decode the string first and than check for valid (or invalid) characters.
i.e. something like /[\w ]/ (empty is a space)
With a regex in the first place you need to respect that www.example.com/index.html?user=admin&pass=%%250 means that the pass really is "%250".
Another solution if look-arounds are not available:
^([^%]|%([013-9a-fA-F][0-9a-fA-F]|2[1-9a-fA-F]))*$
Reject the string if it matches %[^2][^0]
I think that would find what you need
/^([^%]|%%|%20)+$/
Edit: Added case where %% is valid string inside URI
Edit2: And fixed it for case where it should fail :-)
Edit3:
In case you need to use it in editor (which would explain why you can't use more programmatic way), then you have to correctly escape all special characters, for example in Vim that regex should lool:
/^\([^%]\|%%\|%20\)\+$/
Maybe a better approach is to deal with that validation after you decode that string:
string name = HttpUtility.UrlDecode(Request.QueryString["Name"]);
/^([^%]|%20)*$/
This requires a test against the "bad" patterns. If we're allowing %20 - we don't need to make sure it exists.
As others have said before, %% is valid too... and %%25would be %25
The below regex matches anything that doesn't fit into the above rules
/(?<![^%]%)%(?!(20|%))/
The first brackets check whether there is a % before the character (meaning that it's %%) and also checks that it's not %%%. it then checks for a %, and checks whether the item after doesn't match 20
This means that if anything is identified by the regex, then you should probably reject it.
I agree with dominic's comment on the question. Don't use Regex.
If you want to avoid scanning the string twice, you can just iteratively search for % and then check that it is being followed by 20 and nothing else. (Update: allow a % after to be interpreted as a literal %nnn sequence)
// pseudo code
pos = 0
while (pos = mystring.find(pos, '%'))
{
if mystring[pos+1] = "%" then
pos = pos + 2 // ok, this is a literal, skip ahead
else if mystring.substring(pos,2) != "20"
return false; // string is invalid
end if
}
return true;