Regular expression to extract valid cell references from a spreadsheet formula

Question

I am attempting to extract valid cell references and range references from a spreadsheet formula, using Google Apps Script (Javascript).

A valid cell reference is one or two letters, followed by consecutive numbers not starting with a zero. Either the letter(s) or the number(s) may or may not be preceded by a $ character. The entire reference can't be preceded/proceeded by a letter, number or underscore (in which case it may be part of either a spreadsheet function or the name of a named range) or a colon (in which case it may be part of range reference).

The range reference regex (rangeRefRe) seems to work well; but my cell reference regex (cellRefRe) fails to find a match. Would be great if someone could point out what I'm doing wrong.

function myFunction()
{
  var formula = '=A100+B$2:2+INDIRECT("A2:B")+$C3-SUM($D$1:$E5)';
  var fSegments = formula.split('"'); // I want to exclude references within double quotation marks
  var rangeRefRe = /[^0-9a-zA-Z_$]([0-9a-zA-Z$]+?:[0-9a-zA-Z$]+)(?![0-9a-zA-Z_])/g;
  var cellRefRe = /[^0-9a-zA-Z_$:](\${,1}[a-zA-Z]{1,2}\${,1}[1-9][0-9]*)(?![0-9a-zA-Z_:])/g;
  var refResult;
  var references = [];
  for (var i = 0; i < fSegments.length; i += 2)
  {
    while (refResult = rangeRefRe.exec(fSegments[i]))
    {
      references.push(refResult[1]);
    }
    while (refResult = cellRefRe.exec(fSegments[i]))
    {
      references.push(refResult[1]);
    }
  }
  Logger.log(references);
}

score 4 · Accepted Answer · answered Jan 18 '14 at 03:29

4

JavaScript doesn't support this part of your regex: {,1}. To allow 0 or 1 occurrences it would need to be {0,1}, or you can replace that with just ?:

/[^0-9a-zA-Z_$:](\$?[a-zA-Z]{1,2}\$?[1-9][0-9]*)(?![0-9a-zA-Z_:])/g;

answered Jan 18 '14 at 03:29

nnnnnn

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Ah many thanks. I even had a regex reference website open showing Javascript support as well. :-( But the ? quantifier was all I needed anyway. – AdamL Jan 18 '14 at 03:34
1

You're welcome. Note that I said "JavaScript doesn't support" because other regex implementations might allow it, but having said that I'm pretty sure none of the other languages I code in accept it either. In the `{m,n}` format you can omit the `n`, so `{3,}` means "at least 3", but you can't omit the `m`... – nnnnnn Jan 18 '14 at 03:45

score 3 · Answer 2 · answered Apr 20 '16 at 01:33

The question and answers were incredibly helpful but I ran into a few problems so here are some notes for future readers:

It might be good to add "(" to the characters the regex can't end in. The formula could contain a call to a custom function named "a1" or something similar. Adding left-parenthesis would prevent matching a call to such badly named custom functions.
While "A2:A" and "A1:2" are valid ranges, ranges like "A:2" are not.
I needed the references ordered in the way they appeared in the formula. A single regex for both ranges and cells would solve that problem.

Here's the regex I came up with:

/[^0-9a-zA-Z_$:]\$?([a-zA-Z]+(\$?[1-9]\d*(:(\$?[a-zA-Z]+)?\$?([1-9]\d*)?)?|((:\$?[a-zA-Z]+\$?([1-9]\d*)?))))(?![0-9a-zA-Z_(])/g;

score 1 · Answer 3 · answered Jan 18 '14 at 03:30

1

The correct regex should be:

/[^0-9a-zA-Z_$:](\$?[a-zA-Z]{1,2}\$?[1-9][0-9]*)(?![0-9a-zA-Z_:])/

answered Jan 18 '14 at 03:30

Iulian Onofrei

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score 1 · Answer 4 · edited May 23 '17 at 10:30

Variation to the regex posted by Josh Dawson to include sheet names.

var formula = '=data!A100+B$2:2+INDIRECT("A2:B")+\'Sheet 1\'!$C3-SUM($D$1:$E5)';
var fSegments = formula.split('"'); // I want to exclude references within double quotation marks
var re = /[^0-9a-zA-Z_$:]((((\'.+\')|([a-zA-Z0-9]+))\!)?\$?([a-zA-Z]+(\$?[1-9]\d*)(:(\$?[a-zA-Z]+)?\$?([1-9]\d*)?)?|((:\$?[a-zA-Z]+\$?([1-9]\d*)?))))/g;
var refResult;
var references = [];
for (var i = 0; i < fSegments.length; i += 2) {
  while (refResult = re.exec(fSegments[i])) {
    references.push(refResult[1]);
  }
}
console.log(references);

Simon Woodward · Answer 5 · 2019-03-13T22:34:59.207

I have been doing the same thing in R, and thought I'd add my method. It includes references to external workbooks. I did not include such things as B$2:2 as I have never seen them in the wild.

# Thanks to https://www.get-digital-help.com/2017/02/07/extract-cell-references-from-a-formula/
library(stringr)
formula <- "=data!A100+'[C:\\temp dir\\book.xlsx]Sheet 1'!$C3-SUM($D$1:$E5)"
book <- "\\[[a-zA-Z0-9][a-zA-Z0-9\\s\\+\\-\\&\\_\\.\\:\\\\]*\\]" # add any needed filepath characters
sheet <- "[a-zA-Z][a-zA-Z0-9\\s\\+\\-\\&\\_\\(\\)]*" # add any needed sheetname characters
range <- "\\$?[A-Z]+\\$?[0-9]+(:\\$?[A-Z]+\\$?[0-9]+)?(?!\\()" # not followed by (
pattern <- paste0("('?((", book, ")?", sheet, ")'?!)?", range)
pattern
#> [1] "('?((\\[[a-zA-Z0-9][a-zA-Z0-9\\s\\+\\-\\&\\_\\.\\:\\\\]*\\])?[a-zA-Z][a-zA-Z0-9\\s\\+\\-\\&\\_\\(\\)]*)'?!)?\\$?[A-Z]+\\$?[0-9]+(:\\$?[A-Z]+\\$?[0-9]+)?"
str_extract_all(formula, pattern, simplify=TRUE) # matrix
#>      [,1]        [,2]                                     [,3]      
#> [1,] "data!A100" "'[C:\\temp dir\\book.xlsx]Sheet 1'!$C3" "$D$1:$E5"

^{Created on 2019-03-14 by the reprex package (v0.2.1)}

Regular expression to extract valid cell references from a spreadsheet formula

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