Combining regex to retrieve match cases

Question

I have the following string

[1] weight | width | depth | 5.0 cm | 6.0 mm^2 | 10.12 cm^3

From that I need to extract the name, value and units from the above string like below

name = weight
value = 5.0
unit = cm

name = width
value = 6.0
unit = cm^2

name = depth
value = 10.12
unit = cm^3

I have the following regexes for each match cases. Individually each one is working as expected. But combining the regex is needed, so it will return the expected match cases. I tried just combining them all and also using |. But not worked. Here is the working regex for individual matches

For Name : (?<name>\b\w+(?:[\w]\w+)+\b)
For Value : (?<![\^])(?<value>[+-]?[0-9]+(?:\.[0-9]+)?)(?!\S)
For Unit : \b[0-9]+(?:\.[0-9]+)?[^\S\r\n]+(?<unit>[^0-9\s]\S*)(?:[^\S\r\n]+\||$)

Can anyone help me on this. Thanks

Yes. It will always contains name, value and unit fields separated by space and pipes(|) — Aneesh Narayanan
– Aneesh Narayanan, Commented Jun 23, 2022 at 6:36

anubhava · Accepted Answer · 2022-06-23 06:55:10Z

4

If there are the same amount of pipes, you can use a capture group for name, and capture value and unit in a lookahead:

(?<!\S)(?<name>\w+)(?=(?:[^|]*\|){3}\s*\b(?<value>[0-9]+(?:\.[0-9]+)?)\s+(?<unit>[^0-9\s]\S*))

Regex demo

edited Jun 23, 2022 at 6:55

anubhava

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answered Jun 23, 2022 at 6:49

The fourth bird

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9 Comments

JvdV Over a year ago

To make this work for OP I think we need to think of the {3} as being {n} rather where OP would find the occurence of the '|' in the string first and devide by 2 (round up to 1st integer in case of just a single pipe).

The fourth bird Over a year ago

@JvdV Yes if you have 2 occurrences of the pipe, then the n will be 2. If this is dynamic, you can use logic like you described, or use split and do afterprocessing.

JvdV Over a year ago

Yeah, looking at the samples OP provided (in question and comment) the latter (split) may also be a good alternative.

Aneesh Narayanan Over a year ago

Thanks for the answers. The format is always same. But the data group count may differ. The string I provided in the question has 3 groups. But the group count may differ. It should support any group count. Like below [1] ABC | XYZ | 6.9 mm | 194 mm^3

JvdV Over a year ago

Enjoy wherever you are! Not too much SO during holidays OK =)

|

JvdV · Accepted Answer · 2022-06-23 09:48:54Z

2

Just for reference on how you could use the pattern provided by @TheFourthBird

using System;
using System.Text.RegularExpressions;
using System.Linq;
                    
public class Program
{
    public static void Main()
    {
        string s = "[1] weight | width | depth | 5.0 cm | 6.0 mm^2 | 10.12 cm^3";
        int n = s.Split('|').Length / 2;
        string pat = @"(?<!\S)(?<name>\w+)(?=(?:[^|]*\|){" + n + @"}\s*\b(?<value>[0-9]+(?:\.[0-9]+)?)\s+(?<unit>[^0-9\s]\S*))";
        
        var ItemRegex = new Regex(pat, RegexOptions.Compiled);
        var OrderList = ItemRegex.Matches(s)
                            .Cast<Match>()
                            .Select(m => new
                            {
                                Name = m.Groups["name"].ToString(),
                                Value = Convert.ToDouble(m.Groups["value"].ToString()),
                                Unit = m.Groups["unit"].ToString(),
                            })
                            .ToList();
        Console.WriteLine(String.Join("; ", OrderList));
    }
}

Prints:

{ Name = weight, Value = 5, Unit = cm }; { Name = width, Value = 6, Unit = mm^2 }; { Name = depth, Value = 10.12, Unit = cm^3 }

Give it a go with other samples here

Note: By no means am I an c# developer. I just so happen to adjust code found here on SO to showcase how the answer given by TheFourthBird could work.

edited Jun 23, 2022 at 9:48

answered Jun 23, 2022 at 9:30

JvdV

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3 Comments

Aneesh Narayanan Over a year ago

Thanks for sharing the code. I already have a logic for parsing the match groups(That is fixed and cannot change at this moment). And in that the regex is reading from a json file. So I can easily change the regex for supporting the text string. So is it possible to modify the regex without explicitly specifying the value of 'n'

JvdV Over a year ago

@AneeshNarayanan, not possible through regex afaik.

Aneesh Narayanan Over a year ago

Hm. Thanks for the update. I was thinking that, if the match grouping is working individually without specifying the 'n' value, combining them in any way will work ?

Artyom Vancyan · Accepted Answer · 2022-06-23 06:48:25Z

1

Use this regex to capture the corresponding groups

\[\d+\]\s(\w+)\s\|\s(\w+)\s\|\s(\w+)\s\|\s(\S+)\s(\S+)\s\|\s(\S+)\s(\S+)\s\|\s(\S+)\s(\S+)

Then using substitution replace with

name = $1\nvalue = $4\nunit = $5\n\nname = $2\nvalue = $6\nunit = $7\n\nname = $3\nvalue = $8\nunit = $9

See the regex demo. Also, see C# demo.

answered Jun 23, 2022 at 6:48

Artyom Vancyan

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