Writing a function to extract integers from strings using regular expressions

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Trying to Write function integers_in_brackets that finds from a given string all integers that are enclosed in brackets.

Example run: integers_in_brackets(" afd [asd] [12 ] [a34] [ -43 ]tt [+12]xxx") returns [12, -43, 12]. So there can be whitespace between the number and the brackets, but no other character besides those that make up the integer.

My progress so far was:

def integers_in_brackets(s):
    r= []
    patt = re.compile(r'\W\s*(-?\d+)')
    for i in patt.findall(s):
        r.append(int(i))
    return r

Yet i seem to fail in TMC where I only achieve 66% of the required

Failed: test.test_integers_in_brackets.IntegersInBrackets.test_second
        Lists differ: [128, 47, -43, 12] != [47, 12]

First differing element 0:
128
47

First list contains 2 additional elements.
First extra element 2:
-43

- [128, 47, -43, 12]
+ [47, 12] : Incorrect result for string   afd [128+] [47 ] [a34]  [ +-43 ]tt [+12]xxx!

Test results: 2/3 tests passed
 66%[????????????????????????????????????????????????????????????????]

This should work:

import re
pat=r"(?:\[(\s*?[-+]?\d+\s*?)\])"
list(map(eval, re.findall(pat, "  afd [asd] [12 ] [a34]  [ -43 ]tt [+12]")))                                                                                                        
#[12, -43, 12]

How can I extract a portion of a string variable using regular , We will show some examples of how to use regular expression to extract and/or of all the regular expression operators as well as the functions that work with of these expressions together will enable us to find a string of exactly five digits. Regular expressions are a tool used to extract a required part of the text by using advanced manipulations. Java substring() utility is a very powerful library if you want to perform multiple special operations on String. You can always iterate through each character and build a new string (Use the StringBuilder class).

Explicit brackets should work:

def integers_in_brackets(s):
    r= []
    patt = re.compile(r'\[\s*(\+?-?\d+)\s*\]')
    for i in patt.findall(s):
        r.append(int(i))
    return r

How to extract numbers from a string using regular expressions?, You can match numbers in the given string using either of the following regular expressions −“\\d+” Or, ([0-9]+)Example 1import java.util. Regular expressions are a tool used to extract a required part of the text by using advanced manipulations. Regular expressions are popular when testing web applications because they can be used to validate and to perform operations on a response from a web application.

Easy and more straightforward way to do it:

re.findall(r'\[\s*([+-]?\d+)\s*\]',"  afd [asd] [12 ] [a34]  [ -43 ]tt [+12]")

How to extract numbers from a string and get an array of ints , \d matches a digit, and we need to write \ as \\ in a Java String though. like 2-34 (this can also be handled purely with regex in split , but it's fairly complicated). A regular expression (sometimes called a rational expression) is a sequence of characters that define a search pattern, mainly for use in pattern matching with strings, or string matching, i.e. “find and replace”-like operations.(Wikipedia). Regular expressions are a generalized way to match patterns with sequences of characters.

Find all the numbers in a string using regular expression in Python , Approach: The idea is to use Python re library to extract the sub-strings from the given string which match the pattern [0-9]+. This pattern will� The basic outline of this problem is to read the file, look for integers using the re.findall(), looking for a regular expression of '[0-9]+' and then converting the extracted strings to integers and summing up the integers. Turn in Assignent. Enter the sum from the actual data and your Python code below: Sum: (ends with 152)

Regexp function to extract numbers - User Interface, Regexp function to extract numbers tointeger() function will try to convert the string to integer and it will strips the non-digits For example: tointeger("a. How To Extract A Substring From A String In Java Using Regex

Snowflake Extract Numbers using Regular Expression Functions , Snowflake Extract Numbers from the string examples. The regular expression functions come handy when you want to extract numerical values� In this article, we show how to extract only non-alphanumeric characters from a string in Python using regular expressions. Fuzzy String Matching, also called Approximate String Matching, is the process of finding strings that approximatively match a given pattern.

Comments
  • The Movie Channel has coding exercises?
  • TMC stands for Test My Code it's a learning platform by the University of Helsinki Here is a link: tmc.mooc.fi
  • This is a great concept yet it fails when facing multiple spaces before an int example: s = " afd [asd] [12 ] [a34] [ -43 ]tt [+12]xxx!"
  • If you are kind enough could you point out what the " : " indicates as well as the first and last escape rules what are they escaping
  • I created: regex101.com/r/7Oe2a6/1 if you want to try it, if you have an example it doesn't work i can modify it
  • that works like a charm but could you please elaborate what is a non capturing group aka " (?:) "
  • When you use (?:) it means that the group is matched but is not captured for back-referencing i.e non-capturing group. It's not stored in memory to be referenced later on. I hope that helps
  • this forms a complication as there is a +-43 where it appends it to the list as +-43 which is invalid and doesn't filter out the + If you could explain what does the first \ indicates I'd be thankfull what is it escaping
  • @OmarAhmed It is an escape.
  • For what exactly if i may ask?
  • @OmarAhmed [ starts a character class in regex, but \[ is a literal [.