Regex to find repeating numbers between other numbers - regex

Question

I have the following array and need two Regex filters that I want to use in PowerShell.
000111
010101
220220
123456
Filter 1: the number 0 that occurs equal or more than three times.
I expect the following values after filtering
000111
010101
Filter 2: all numbers that occur equal or more than three times.
I should only see these numbers.
000111
010101
220220
With 0{3,} I can only recognize numbers in sequence so i get only the number
000111
Is it possible to find repeating numbers that are between other numbers?

Answer 1

Since you insist to see the solution in regex, look at this: '(\d).*\1.*\1'
I think this is comprehensible without further explanation, isn't it?

Answer 2

Armali's helpful answer is short and to the point (use '(0).*\1.*\1' for filter 1), and definitely the best solution for the problem at hand, given that you only need to know in the abstract if a given string has 3 or more zeros / same digits.
The solutions below may be of interest if you need to know the specific count of 0s / digits, which, as far as I know, cannot be handled by a regex (alone)
Occurrence-counting variant of filter 1:
#(
'000111'
'010101'
'220220'
'123456'
).ForEach({
$zerosOnly = $_ -replace '[^0]'
[pscustomobject] #{
InputString = $_
CountOfZeros = $zerosOnly.Length
}
})
That is, each string in the input array (enumerated via the intrinsic ForEach() method), has all chars. that aren't '0' ([^0]) removed via the regex-based -replace operator. The length of the resulting string is therefore equivalent to the count of zeros.
Output:
InputString CountOfZeros
----------- ------------
000111 3
010101 3
220220 2
123456 0
Occurrence-counting variant of filter 2
#(
'000111'
'010101'
'220220'
'123456'
).ForEach({
$outputObject = [pscustomobject] #{ InputString = $_; DigitCounts = [ordered] #{} }
([char[]] $_ | Group-Object).ForEach({
$outputObject.DigitCounts[$_.Name] = $_.Count
})
$outputObject
})
That is, each input string by is grouped by its characters using Group-Object, whose output objects reflect the character at hand in the .Name property and the number of members of the group - i.e. the occurrence count for that character in the .Count property. An ordered hashtable is used to report character-occurrence-count pairs.
Output:
InputString DigitCounts
----------- -----------
000111 {[0, 3], [1, 3]}
010101 {[0, 3], [1, 3]}
220220 {[0, 2], [2, 4]}
123456 {[1, 1], [2, 1], [3, 1], [4, 1]…}
E.g., {[0, 2], [2, 4]} in the output above means that the char. '0' occurs 2 times, and '2' 4 times in input string '220220'.