Remove alphanumeric chars in front of a defined char - excel

Question

I have a string in a cell composed of several shorter strings of various lengths with blank spaces and commas in between. In some cases only one or more blanks are in between.
I want to remove every blank space and comma and only leave behind 1 comma between each string element. The result must look like this:
The following doesn't work. I'm not getting an error but the strings are truncated at the wrong places. I don't understand why.
Sub String_adaption()
Dim i, j, k, m As Long
Dim STR_A As String
STR_A = "01234567890ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
i = 1
With Worksheets("table")
For m = 1 To Len(.Range("H" & i))
j = 1
Do While Mid(.Range("H" & i), m, 1) = "," And Mid(.Range("H" & i), m - 1, 1) <> Mid(STR_A, j, 1) And m <> Len(.Range("H" & i))
.Range("H" & i) = Mid(.Range("H" & i), 1, m - 2) & Mid(.Range("H" & i), m, Len(.Range("H" & i)))
j = j + 1
Loop
Next m
End With
End Sub

Answer 1

I'd use a regular expression to replace any combination of spaces and comma's. Something along these lines:
Sub Test()
Dim str As String: str = "STRING_22 ,,,,,STRING_1 , , ,,,,,STRING_333 STRING_22 STRING_4444"
Debug.Print RegexReplace(str, "[\s,]+", ",")
End Sub
Function RegexReplace(x_in, pat, repl) As String
With CreateObject("vbscript.regexp")
.Global = True
.Pattern = pat
RegexReplace = .Replace(x_in, repl)
End With
End Function
Just for the sake of alternatives:
Formula in B1:
=TEXTJOIN(",",,TEXTSPLIT(A1,{" ",","}))

Answer 2

The following function will split the input string into pieces (words), using a comma as separator. When the input string has multiple commas, it will result in empty words.
After splitting, the function loops over all words, trims them (remove leading and trailing blanks) and glue them together. Empty words will be skipped.
I have implemented it as Function, you could use it as UDF: If your input string is in B2, write =String_adaption(B2) as Formula into any cell.
Function String_adaption(s As String) As String
' Remove duplicate Commas and Leading and Trailing Blanks from words
Dim words() As String, i As Long
words = Split(s, ",")
For i = 0 To UBound(words)
Dim word As String
word = Trim(words(i))
If word <> "" Then
String_adaption = String_adaption & IIf(String_adaption = "", "", ",") & word
End If
Next i
End Function
P.S.: Almost sure that this could be done with some magic regular expressions, but I'm not an expert in that.

Answer 3

If you have recent Excel version, you can use simple worksheet function to split the string on space and on comma; then put it back together using the comma deliminater and ignoring the blanks (and I just noted #JvdV had previously posted the same formula solution):
=TEXTJOIN(",",TRUE,TEXTSPLIT(A1,{" ",","}))
In VBA, you can use a similar algorithm, using the ArrayList object to collect the non-blank results.
Option Explicit
Function commaOnly(s As String) As String
Dim v, w, x, y
Dim al As Object
Set al = CreateObject("System.Collections.ArrayList")
v = Split(s, " ")
For Each w In v
x = Split(w, ",")
For Each y In x
If y <> "" Then al.Add y
Next y
Next w
commaOnly = Join(al.toarray, ",")
End Function

Answer 4

This preserves the spaces within the smaller strings.
Option Explicit
Sub demo()
Const s = "STRING 22,,,, ,,STRING 1,,,, ,,STRING 333 , , , STRING_22 STRING_44"
Debug.Print Cleanup(s)
End Sub
Function Cleanup(s As String) As String
Const SEP = ","
Dim regex, m, sOut As String, i As Long, ar()
Set regex = CreateObject("vbscript.regexp")
With regex
.Global = True
.MultiLine = False
.IgnoreCase = True
.Pattern = "([^,]+)(?:[ ,]*)"
End With
If regex.Test(s) Then
Set m = regex.Execute(s)
ReDim ar(0 To m.Count - 1)
For i = 0 To UBound(ar)
ar(i) = Trim(m(i).submatches(0))
Next
End If
Cleanup = Join(ar, SEP)
End Function

Answer 5

Code categories approach
For the sake of completeness and to show also other ways "leading to Rome", I want to demonstrate an approach allowing to group the string input into five code categories in order to extract alphanumerics by a tricky match (see [B] Function getCats()):
To meet the requirements in OP use the following steps:
1) remove comma separated tokens if empty or only blanks (optional),
2) group characters into code categories,
3) check catCodes returning alpha nums including even accented or diacritic letters as well as characters like [ -,.+_]
Function AlphaNum(ByVal s As String, _
Optional IgnoreEmpty As Boolean = True, _
Optional info As Boolean = False) As String
'Site: https://stackoverflow.com/questions/15723672/how-to-remove-all-non-alphanumeric-characters-from-a-string-except-period-and-sp/74679416#74679416
'Auth.: https://stackoverflow.com/users/6460297/t-m
'Date: 2023-01-12
'1) remove comma separated tokens if empty or only blanks (s passed as byRef argument)
If IgnoreEmpty Then RemoveEmpty s ' << [A] RemoveEmpty
'2) group characters into code categories
Dim catCodes: catCodes = getCats(s, info) ' << [B] getCats()
'3) check catCodes and return alpha nums plus chars like [ -,.+_]
Dim i As Long, ii As Long
For i = 1 To UBound(catCodes)
' get current character
Dim curr As String: curr = Mid$(s, i, 1)
Dim okay As Boolean: okay = False
Select Case catCodes(i)
' AlphaNum: cat.4=digits, cat.5=alpha letters
Case Is >= 4: okay = True
' Category 2: allow only space, comma, minus
Case 2: If InStr(" -,", curr) <> 0 Then okay = True
' Category 3: allow only point, plus, underline
Case 3: If InStr(".+_", curr) <> 0 Then okay = True
End Select
If okay Then ii = ii + 1: catCodes(ii) = curr ' increment counter
Next i
ReDim Preserve catCodes(1 To ii)
AlphaNum = Join(catCodes, vbNullString)
End Function
Note: Instead of If InStr(" -,", curr) <> 0 Then in Case 2 you may code If curr like "[ -,]" Then, too. Similar in Case 3 :-)
[A] Helper procedure RemoveEmpty
Optional clean-up removing comma separated tokens if empty or containing only blanks:
Sub RemoveEmpty(ByRef s As String)
'Purp: remove comma separated tokens if empty or only blanks
Const DEL = "$DEL$" ' temporary deletion marker
Dim i As Long
Dim tmp: tmp = Split(s, ",")
For i = LBound(tmp) To UBound(tmp)
tmp(i) = IIf(Len(Trim(tmp(i))) = 0, DEL, Trim(tmp(i)))
Next i
tmp = Filter(tmp, DEL, False) ' remove marked elements
s = Join(tmp, ",")
End Sub
[B] Helper function getCats()
A tricky way to groups characters into five code categories, thus building the basic logic for any further analyzing:
Function getCats(s, Optional info As Boolean = False)
'Purp.: group characters into five code categories
'Auth.: https://stackoverflow.com/users/6460297/t-m
'Site: https://stackoverflow.com/questions/15723672/how-to-remove-all-non-alphanumeric-characters-from-a-string-except-period-and-sp/74679416#74679416
'Note: Cat.: including:
' 1 ~~> apostrophe '
' 2 ~~> space, comma, minus etc
' 3 ~~> point separ., plus etc
' 4 ~~> digits 0..9
' 5 ~~> alpha (even including accented or diacritic letters!)
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'a) get array of single characters
Const CATEG As String = "' - . 0 A" 'define group starters (case indep.)
Dim arr: arr = Char2Arr(s) ' << [C] Char2Arr()
Dim chars: chars = Split(CATEG)
'b) return codes per array element
getCats = Application.Match(arr, chars) 'No 3rd zero-argument!!
'c) display in immediate window (optionally)
If info Then Debug.Print Join(arr, "|") & vbNewLine & Join(getCats, "|")
End Function
[C] Helper function Char2Arr
Assigns every string character to an array:
Function Char2Arr(ByVal s As String)
'Purp.: assign single characters to array
s = StrConv(s, vbUnicode)
Char2Arr = Split(s, vbNullChar, Len(s) \ 2)
End Function