Character classes in regular expressions
Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. First, please read here for information on regular expressions. It's worth learning. In the end it reads "replace any character that is not a word character or a space character with nothing. This code shows the full RegEx replace process and gives a sample Regex that only keeps letters, numbers, and spaces in a string - replacing ALL other characters with an empty string:.
Learn more. Remove punctuation from string with Regex Ask Question. Asked 8 years, 11 months ago. Active 10 days ago. Viewed 41k times. I'm really bad with Regex but I want to remove all these.
Best way to remove punctuation from a String?
Sjemmie Sjemmie 1, 6 6 gold badges 22 22 silver badges 31 31 bronze badges. Why not simply run a string. The performance will undoubtedly be better and the code will be much more readable to boot. This was answered here already: stackoverflow. Tejs: The performance may or may not be better, depending on the length of the string and the number of characters that need to be replaced.
Also, the code would not necessarily be less readable. A lot of people have an aversion to using regular expressions because they do look cryptic, but just like any other code - commenting them will help with that.
May 3 '11 at Josh M. Active Oldest Votes. You can use this: Regex. Replace "This is a test string, with lots of: punctuations; in it?!. Updating my answer This is a beautiful answer. Replace stringToParse, String. Justin Gengo S. Justin Gengo 11 3 3 bronze badges. Hi Daniel, happy to do so.For instance, you may want to remove all punctuation marks from text documents before they can be used for text classification.
Similarly, you may want to extract numbers from a text string. Writing manual scripts for such preprocessing tasks requires a lot of effort and is prone to errors. Keeping in view the importance of these preprocessing tasks, the Regular Expressions aka Regex have been developed in different languages in order to ease these text preprocessing tasks.
How to remove all special characters, punctuation and spaces from a string in Python?
A Regular Expression is a text string that describes a search pattern which can be used to match or replace patterns inside a string with a minimal amount of code.
In this tutorial, we will implement different types of regular expressions in the Python language. To implement regular expressions, the Python's re package can be used. Import the Python's re package with the following command:. One of the most common NLP tasks is to search if a string contains a certain pattern or not. For instance, you may want to perform an operation on the string based on the condition that the string contains a number. To search a pattern within a string, the match and findall function of the re package is used.
The first parameter of the match function is the regex expression that you want to search. Regex expression starts with the alphabet r followed by the pattern that you want to search. The pattern should be enclosed in single or double quotes like any other string.
The above regex expression will match the text string, since we are trying to match a string of any length and any character. In case if no match is found by the match function, a null object is returned. Now the previous regex expression matches a string with any length and any character.
It will also match an empty string of length zero. To test this, update the value of text variable with an empty string:. Since we specified to match the string with any length and any character, even an empty string is being matched. The match function can be used to find any alphabet letters within a string.
It only takes a minute to sign up. You can replace commas with a non-punctuation character, remove all remaining puctuation, then restore the commas:. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Regular expression to remove all punctuation except commas in regex awk Ask Question.
Asked 1 year, 2 months ago. Active 1 year, 2 months ago. Viewed times. Please provide some more context.
I think you might better of using a json parser instead of trying to remove characters from your string. And please fix your code as it's not valid.
Still no context. And if it's all inside awkyou might want to remove the shell tag from the question. What exactly is not working. I think you should edit your question to include a complete, piece of awk code that exhibits the issue so any readers can repeat it. Active Oldest Votes. Sign up or log in Sign up using Google. Sign up using Facebook.
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Best way to remove punctuation from a String?
Feedback on Q2 Community Roadmap. Related 0. Hot Network Questions. Question feed.This document is an introductory tutorial to using regular expressions in Python with the re module. It provides a gentler introduction than the corresponding section in the Library Reference. Regular expressions called REs, or regexes, or regex patterns are essentially a tiny, highly specialized programming language embedded inside Python and made available through the re module.
Using this little language, you specify the rules for the set of possible strings that you want to match; this set might contain English sentences, or e-mail addresses, or TeX commands, or anything you like. You can also use REs to modify a string or to split it apart in various ways. Regular expression patterns are compiled into a series of bytecodes which are then executed by a matching engine written in C.
For advanced use, it may be necessary to pay careful attention to how the engine will execute a given RE, and write the RE in a certain way in order to produce bytecode that runs faster. The regular expression language is relatively small and restricted, so not all possible string processing tasks can be done using regular expressions.
There are also tasks that can be done with regular expressions, but the expressions turn out to be very complicated. In these cases, you may be better off writing Python code to do the processing; while Python code will be slower than an elaborate regular expression, it will also probably be more understandable.
For a detailed explanation of the computer science underlying regular expressions deterministic and non-deterministic finite automatayou can refer to almost any textbook on writing compilers. Most letters and characters will simply match themselves. For example, the regular expression test will match the string test exactly.
Instead, they signal that some out-of-the-ordinary thing should be matched, or they affect other portions of the RE by repeating them or changing their meaning. Much of this document is devoted to discussing various metacharacters and what they do.
Characters can be listed individually, or a range of characters can be indicated by giving two characters and separating them by a '-'. For example, [abc] will match any of the characters abor c ; this is the same as [a-c]which uses a range to express the same set of characters. If you wanted to match only lowercase letters, your RE would be [a-z]. Metacharacters are not active inside classes. You can match the characters not listed within the class by complementing the set.
As in Python string literals, the backslash can be followed by various characters to signal various special sequences. The following predefined special sequences are a subset of those available.
The equivalent classes are for bytes patterns. For a complete list of sequences and expanded class definitions for Unicode string patterns, see the last part of Regular Expression Syntax. These sequences can be included inside a character class. The final metacharacter in this section is. Another capability is that you can specify that portions of the RE must be repeated a certain number of times.
A step-by-step example will make this more obvious. This matches the letter 'a'zero or more letters from the class [bcd]and finally ends with a 'b'. Now imagine matching this RE against the string abcbd.
It only takes a minute to sign up. You can replace commas with a non-punctuation character, remove all remaining puctuation, then restore the commas:. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Regular expression to remove all punctuation except commas in regex awk Ask Question. Asked 1 year, 2 months ago. Active 1 year, 2 months ago.
Viewed times. Please provide some more context. I think you might better of using a json parser instead of trying to remove characters from your string. And please fix your code as it's not valid. Still no context.
If you continue browsing our website, you accept these cookies. The only characters I want to retain are letters a-z case doesn't matter and numbers 0 to 9. I'm working with web services that don't like punctuation, but I don't want to code string values with a generic recordID because I still want the results to be readable. Basically, anything that isn't a to z or 0 to 9 can just be thrown away. I this easy to do? Go to Solution. Oh wow that was easy! I didn't even know there was a Regex tool, I thought I'd have to mess around with a function in a formula or filter.
That makes life much easier! Thank you. Just check the "Punctuation" box under the "Remove Unwanted Characters" section. Learn more. Turn on suggestions. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. Showing results for. Search instead for. Did you mean:. Sign In. Alteryx designer Discussions Find answers, ask questions, and share expertise about Alteryx Designer.
Alteryx is here to help you solve your biggest data challenges. Read about the new Virtual Solution Center here.This works, but it's not very elegant. Must be a generic term for 'punctuation' I can use inside the gsub?
The code you have above is really the only way to remove specific parts of a string and what you have is as elegant as regular expressions get. You could use a shorter regex that simply accepts only uppercase and lowercase letters, numbers and spaces:. You can play with Ruby regexes here to make sure your code does what you want aside from testing it in your own program:.
The i at the end probably is not necessary, but make sure you test it properly. I used this for the challenge. It seemed to work as it removed the "! You saved me so much time! Best answer so far. I was just through Salt Lake City. So beautiful I didn't like that my liberal punctuation was being replaced by the odd extra space say, after a period. Posting to the forum is only allowed for members with active accounts. Please sign in or sign up to post.
I forgot my password. Andrew Stelmach 12, Points. Extra Credit challenge: remove all punctuation from a string and print it in reverse. Chris Shaw 26, Points. Chris Shaw Chris Shaw 26, Points. Hi Andrew, The code you have above is really the only way to remove specific parts of a string and what you have is as elegant as regular expressions get. Maciej Czuchnowski 36, Points. Maciej Czuchnowski Maciej Czuchnowski 36, Points. You could use a shorter regex that simply accepts only uppercase and lowercase letters, numbers and spaces: string.
Andrew Stelmach Andrew Stelmach 12, Points. That works a treat! My code: puts "Give me a string, fool. Telmen Davaadorj 4, Points. Telmen Davaadorj Telmen Davaadorj 4, Points. Amber Taniuchi 4, Points. Amber Taniuchi Amber Taniuchi 4, Points. Christine Merey 3, Points.
Christine Merey Christine Merey 3, Points. Sign in.