How to select only numbers with specific string in between

Question

I wanna write a regex to select only actual GPS coordinates (not ranges) from the input (below).

This regex returns what I want BUT including the words, I want only numbers:

(actual (lat|lon) (\d+(.\d{1,6})))|((\d+(.\d{1,6})) (lat|lon))

So I want to exclude:

(actual (lat|lon) | (lat|lon))

How do I do that?

Input:

49.212087 latitude, 16.626133 longitude

lat range: 49.000000 to 50.000000 actual lat 49.212059 lon range: 16.000000 to 17.000000 actual lon 16.626276

49.21199 latitude, 16.626446 longitude

lat range: 49.000000 to 50.000000 actual lat 49.212073 lon range: 16.000000 to 17.000000 actual lon 16.626333

Regex match consists of groups, you should be able to retrieve only numbers from these groups. If you are unable to do so, please share your code. — nocodename, Apr 30 '17 at 19:06
This question is confusing about the ranges...Is this a validation question? **Rewrite** this and remove the superfluous text about ranges and concentrate on the regex pattern failure. Or is that the actual **literal** data? If so put it in a quote block or code block. — ΩmegaMan, May 08 '17 at 02:00

Wiktor Stribiżew · Answer 1 · 2017-04-30T20:19:32.157

You have too many unnecessary groups. Also, since you actually need 2 groups to match the same type of value, you may use a named capturing group, and grab all your required matches with a regex like

actual (?:lat|lon) (?<val>\d+\.\d{1,6})|(?<val>\d+\.\d{1,6}) (?:lat|lon)

See the regex demo. If you use a RegexOptions.ExplicitCapture flag, you can use capturing groups as non-capturing ones (only the named capturing groups will keep their submatches). See the C# demo:

var s = "lat range: 49.000000 to 50.000000 actual lat 49.212059 lon range: 16.000000 to 17.000000 actual lon 16.626276";
var pattern = @"actual (lat|lon) (?<val>\d+\.\d{1,6})|(?<val>\d+\.\d{1,6}) (lat|lon)";
var results = Regex.Matches(s, pattern)
        .Cast<Match>()
        .Select(m => m.Groups["val"].Value)
        .ToList();
Console.WriteLine(string.Join("\n", results));
// => 49.212059
//    16.626276

If you put the (lon|lat) into a named capturing group, you will be able to get a dictionary as a result:

var pattern = @"actual (?<type>lat|lon) (?<val>\d+\.\d{1,6})|(?<val>\d+\.\d{1,6}) (?<type>lat|lon)";
var results = Regex.Matches(s, pattern)
     .Cast<Match>()
     .ToDictionary(
            m => m.Groups["type"].Value,
            m => m.Groups["val"].Value);
foreach (var kv in results)
    Console.WriteLine("'{0}': '{1}'", kv.Key, kv.Value);
// => 'lat': '49.212059'
//    'lon': '16.626276'

See another C# demo.

score 0 · Answer 2 · answered Apr 30 '17 at 19:07

Here is working regexp (link to test):

((?<=actual\s(lat|lon)\s)(\d+(.\d{1,6})))|((\d+(.\d{1,6}))(?=\s(lat|lon)))

You can find more information how it's working http://codeasp.net/blogs/microsoft-net/293/c-regex-extract-the-text-between-square-brackets-without-returning-the-brackets-themselves

score 0 · Answer 3 · edited May 23 '17 at 12:18

0

If I've understud your query correctly, this regex should work for you:

(?<=(actual (lat|lon) ))(\d+(.\d{1,6}))|(?<!((lat|lon) range: ))(\d+(.\d{1,6}))(?=( (lat|lon)))

See also my test results on Regexstorm

You can learn more about lookback and lookaheads in this topic: Regex lookahead, lookbehind and atomic groups

edited May 23 '17 at 12:18

Community

1
1

answered Apr 30 '17 at 19:08

Michael Lopez

153
1
9

score 0 · Answer 4 · answered May 08 '17 at 01:57

This regex returns what I want BUT including the words, I want only numbers:

In the realm of regular expressions there is a difference between a match and a capture and basic grouping. You are telling it to match and capture thanks to the ( ) constructs.

Keep these items in mind.

Groups[0] is always the whole match
Groups[1-N] are individual captures when ( ) construct is specified.
Extract your data, the numbers you mentioned) only out of capture groups with index value > 0. Use only Groups[0] when you want just the full match.

([\d.]+)\s(\D+)

Using this pattern on your data, you can get these two matches

Match #0
          [0]:  49.212087 latitude, 
  ["1"] → [1]:  49.212087
  ["2"] → [2]:  latitude, 

Match #1
          [0]:  16.626133 longitude
  ["1"] → [1]:  16.626133
  ["2"] → [2]:  longitude

Named Captures

If one used named captures (?<{name here}), you can access the info via named groups such as mymatch.Groups["Data"].Value or mymatch.Groups[1].Value.

(?<Data>[\d.]+)\s(?<What>\D+)

Use of this pattern has these matches and group captures, which are indexable by int, but also via the quoted strings of "Data" and "What":

Match #0
             [0]:  49.212087 latitude, 
  ["Data"] → [1]:  49.212087
  ["What"] → [2]:  latitude, 

Match #1
             [0]:  16.626133 longitude
  ["Data"] → [1]:  16.626133
  ["What"] → [2]:  longitude

How to select only numbers with specific string in between

4 Answers4