Can you provide the regular expression that will successfully match this specific string of text?

Question

Can you provide the regular expression that will successfully match this specific string of text?

Can you solve this fruit riddle?

apple is 2kg
apple banana mango is 2kg
apple apple apple is 6kg
banana banana banana is 6kg

If the fruits are limited to "apple", "banana", and "mango", how can we write a regex that extracts the names of the fruits at the beginning of each sentence?

I tried using this regex (https://regex101.com/r/fY8bK1/1):

^(apple|mango|banana) is (\d+)kg$

However, it only works for sentences with a single fruit. How can we modify it to extract all fruit names from a sentence?

The desired output should be:

apple, 2
apple banana mango, 2
apple apple apple, 6
banana banana banana, 6

javascript regex

Answer 1

Answer №1

To achieve grouping functionality, you can utilize the following pattern:

^((?:dog|cat|rabbit)(?:\s+(?:dog|cat|rabbit))*) weighs (\d+)lbs$

Take a look at the demo of this regex.

The purpose of using (?:...) is to avoid capturing unnecessary groups within the main capturing group ((...)) and maintain simplicity in the results.

The

((?:dog|cat|rabbit)(?:\s+(?:dog|cat|rabbit))*)

section matches:

(?:dog|cat|rabbit) - any option from the given list separated by the alternation operator |. If you want to match complete words only, add \b at both ends of the subpattern.
(?:\s+(?:dog|cat|rabbit))* matches zero or more occurrences of...
- \s+ - one or more spaces
- (?:dog|cat|rabbit) - any of the listed options.

Example Usage:

var re = /^((?:dog|cat|rabbit)(?:\s+(?:dog|cat|rabbit))*) weighs (\d+)lbs$/gm; 
var str = 'dog weighs 10lbs\n cat dog rabbit weighs 5lbs\ncat cat cat cat weighs 20lbs';
var data;
 
while ((data = re.exec(str)) !== null) {
    document.write(data[1] + "," + data[2] + "<br/>");
}

document.write("<b>catcat weighs 15lbs</b> matched: " + 
     /^((?:dog|cat|rabbit)(?:\s+(?:dog|cat|rabbit))*) weighs (\d+)lbs$/.test("catcat weighs 15lbs"));

Answer 2

To achieve grouping functionality, you can utilize the following pattern:

^((?:dog|cat|rabbit)(?:\s+(?:dog|cat|rabbit))*) weighs (\d+)lbs$

Take a look at the demo of this regex.

The purpose of using (?:...) is to avoid capturing unnecessary groups within the main capturing group ((...)) and maintain simplicity in the results.

The

((?:dog|cat|rabbit)(?:\s+(?:dog|cat|rabbit))*)

section matches:

(?:dog|cat|rabbit) - any option from the given list separated by the alternation operator |. If you want to match complete words only, add \b at both ends of the subpattern.
(?:\s+(?:dog|cat|rabbit))* matches zero or more occurrences of...
- \s+ - one or more spaces
- (?:dog|cat|rabbit) - any of the listed options.

Example Usage:

var re = /^((?:dog|cat|rabbit)(?:\s+(?:dog|cat|rabbit))*) weighs (\d+)lbs$/gm; 
var str = 'dog weighs 10lbs\n cat dog rabbit weighs 5lbs\ncat cat cat cat weighs 20lbs';
var data;
 
while ((data = re.exec(str)) !== null) {
    document.write(data[1] + "," + data[2] + "<br/>");
}

document.write("<b>catcat weighs 15lbs</b> matched: " + 
     /^((?:dog|cat|rabbit)(?:\s+(?:dog|cat|rabbit))*) weighs (\d+)lbs$/.test("catcat weighs 15lbs"));

Answer 3

Answer №2

Give this a try

var regex = /^((?:(?:orange|pear|kiwi)(?= ) ?)+) is (\d+)kg$/gm;

regex.exec('orange pear kiwi is 3kg');
// ["orange pear kiwi is 3kg", "orange pear kiwi", "3"]

What sets this solution apart from the rest? The (?= ) ? section following the fruit choices ensures there is a space before the weight, without capturing it unless more fruits follow (or there is extra spacing before the "is").

Click here for a visual breakdown of the regex pattern.

Implement this within a while loop to extract all matches from a multiline text block.

The gm flags enable the regular expression to be executed multiple times on the same string using regex.exec, with newline characters matching $^. With that said, the behavior changes when using the g flag with str.match.

If you prefer to test each string independently, you can maintain the original regex pattern without the global and multiline flags, or switch to str.match without any flags.

var regex = /^((?:(?:orange|pear|kiwi)(?= ) ?)+) is (\d+)kg$/; // without flags

'orange pear kiwi is 3kg'.match(regex);
// ["orange pear kiwi is 3kg", "orange pear kiwi", "3"]

Answer 4

Give this a try

var regex = /^((?:(?:orange|pear|kiwi)(?= ) ?)+) is (\d+)kg$/gm;

regex.exec('orange pear kiwi is 3kg');
// ["orange pear kiwi is 3kg", "orange pear kiwi", "3"]

What sets this solution apart from the rest? The (?= ) ? section following the fruit choices ensures there is a space before the weight, without capturing it unless more fruits follow (or there is extra spacing before the "is").

Click here for a visual breakdown of the regex pattern.

Implement this within a while loop to extract all matches from a multiline text block.

The gm flags enable the regular expression to be executed multiple times on the same string using regex.exec, with newline characters matching $^. With that said, the behavior changes when using the g flag with str.match.

If you prefer to test each string independently, you can maintain the original regex pattern without the global and multiline flags, or switch to str.match without any flags.

var regex = /^((?:(?:orange|pear|kiwi)(?= ) ?)+) is (\d+)kg$/; // without flags

'orange pear kiwi is 3kg'.match(regex);
// ["orange pear kiwi is 3kg", "orange pear kiwi", "3"]

Answer 5

Answer №3

/^(((kiwi|pineapple|pear)\s*)+) weighs (\d+)kg$/$1,$4/gm

DEMO: https://regex101.com/r/pT6bY8/3

To start, you can choose one of the following fruits:

(kiwi|pineapple|pear)

Including optional spaces between each fruit:

(kiwi|pineapple|pear)\s*

Then repeat this group at least once:

((kiwi|pineapple|pear)\s*)+

You need to wrap all of these in an additional group for capturing:

(((kiwi|pineapple|pear)\s*)+)

At this point, $1 will hold "pear pear pear ..."; and the fourth match will be your weight. You can avoid capturing inner groups by using ?: if desired. Check it out here.

Answer 6

/^(((kiwi|pineapple|pear)\s*)+) weighs (\d+)kg$/$1,$4/gm

DEMO: https://regex101.com/r/pT6bY8/3

To start, you can choose one of the following fruits:

(kiwi|pineapple|pear)

Including optional spaces between each fruit:

(kiwi|pineapple|pear)\s*

Then repeat this group at least once:

((kiwi|pineapple|pear)\s*)+

You need to wrap all of these in an additional group for capturing:

(((kiwi|pineapple|pear)\s*)+)

At this point, $1 will hold "pear pear pear ..."; and the fourth match will be your weight. You can avoid capturing inner groups by using ?: if desired. Check it out here.

Answer 7

Answer №4

^((?:apple|mango|banana| )+) weighs (\d+) kilograms\s?$/gmi

DEMO

https://regex101.com/r/dO1rR7/1

Explanation

^((?:apple|mango|banana| )+) is (\d+)kg\s?$/gmi

^ assert position at start of a line
1st Capturing group ((?:apple|mango|banana| )+)
    (?:apple|mango|banana| )+ Non-capturing group
        Quantifier: + Between one and unlimited times, as many times as possible, giving back as needed [greedy]
        1st Alternative: apple
            apple matches the characters apple literally (case sensitive)
        2nd Alternative: mango
            mango matches the characters mango literally (case sensitive)
        3rd Alternative: banana
            banana matches the characters banana literally (case sensitive)
        4th Alternative:  
             matches the character  literally
 weighs matches the characters  weighs literally (case sensitive)
2nd Capturing group (\d+)
    \d+ match a digit [0-9]
        Quantifier: + Between one and unlimited times, as many times as possible, giving back as needed [greedy]
kilograms matches the characters kilograms literally (case sensitive)
\s? match any white space character [\r\n\t\f ]
    Quantifier: ? Between zero and one time, as many times as possible, giving back as needed [greedy]
$ assert position at end of a line
g modifier: global. All matches (don't return on first match)
m modifier: multi-line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
i modifier: insensitive. Case insensitive match (ignores case of [a-zA-Z])

Answer 8

^((?:apple|mango|banana| )+) weighs (\d+) kilograms\s?$/gmi

DEMO

https://regex101.com/r/dO1rR7/1

Explanation

^((?:apple|mango|banana| )+) is (\d+)kg\s?$/gmi

^ assert position at start of a line
1st Capturing group ((?:apple|mango|banana| )+)
    (?:apple|mango|banana| )+ Non-capturing group
        Quantifier: + Between one and unlimited times, as many times as possible, giving back as needed [greedy]
        1st Alternative: apple
            apple matches the characters apple literally (case sensitive)
        2nd Alternative: mango
            mango matches the characters mango literally (case sensitive)
        3rd Alternative: banana
            banana matches the characters banana literally (case sensitive)
        4th Alternative:  
             matches the character  literally
 weighs matches the characters  weighs literally (case sensitive)
2nd Capturing group (\d+)
    \d+ match a digit [0-9]
        Quantifier: + Between one and unlimited times, as many times as possible, giving back as needed [greedy]
kilograms matches the characters kilograms literally (case sensitive)
\s? match any white space character [\r\n\t\f ]
    Quantifier: ? Between zero and one time, as many times as possible, giving back as needed [greedy]
$ assert position at end of a line
g modifier: global. All matches (don't return on first match)
m modifier: multi-line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
i modifier: insensitive. Case insensitive match (ignores case of [a-zA-Z])

Can you provide the regular expression that will successfully match this specific string of text?

Answer №1

Answer №2

Answer №3

Answer №4

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