Google-sheets – Excluding negative values from summation

The script below will perform a summation throughout tabs, taking into account different strings, as shown in your question.

Code

function mySum(tabRange, strings) {
  // small error handling
  if(typeof tabRange === 'string') {
    throw 'Multiple tabs are needed. Otherwise use SUM';
    return
  }  

  // get active spreasdsheet and create empty arrays
  var ss = SpreadsheetApp.getActive(), aStr = [], output = [];

  // push first result in array to control different strings
  aStr.push(strings[0][0], 0);

  // iterate through tabs
  for(var i = 0, iLen = tabRange.length; i < iLen; i++) {

    // get all data (at once) from tab
    var data = ss.getSheetByName(tabRange[i][0]).getDataRange().getValues();  

    // iterate through strings
    for(var k = 0, kLen = strings.length; k < kLen; k++) {

      // create and set the summation per string
      var strSum = 0;

      // iterate through the data
      for(var j = 0, jLen = data.length; j < jLen; j++) {

        // if a match is found, then add to the strSum
        if(data[j][1] === strings[k][0]) {
          strSum += data[j][0];
        }
      }

      // find index in array that matches a string
      var index = aStr.indexOf(strings[k][0]);

      // if found, then add to existing value
      // else, create a new entry for that string
      // so that it will be found the next time
      if(index !== -1) {
        aStr[index+1] += strSum;
      } else {
        aStr.push(strings[k][0], strSum);
      }
    }
  }

  // get rid off the strings  
  for(var l = 1, lLen = aStr.length; l < lLen; l += 2) {
    output.push(aStr[l]);
  }

  // show the outcome  
  return output; 
}

Screenshot

Example

I've created an example file for you: Sum of dynamic number of values derived from fomula

This can be done by using the running total as an intermediate result (you can put in some column further on the right and/or make it hidden, if you don't want to see it).

I'll use column C for the cumulative total and column D for 7-day total; finding the average is simple division.

The formula for cumulative total is found here. I'll use it in this form

C2 =ARRAYFORMULA(IF(LEN(A2:A), SUMIF(ROW(B2:B),"<="&ROW(B2:B), B2:B), ""))

The conditional statement about LEN(A2:A) prevents output in rows where no data is present.

And here is the computation of 7-day running total:

D2 =ARRAYFORMULA(IF(LEN(A2:A), C2:C-IFERROR(VLOOKUP(A2:A-7, A2:C, 3), 0), ""))

The key player here is the VLOOKUP function which find the latest date that is less than or equal to "a week ago", and returns the cumulative total for it. This represents the total of "old" entries, which should be subtracted from the current total so that only the entries from the last 7 days are counted.

The IFERROR statement handles the case when there is nothing to subtract, i.e., all preceding dates are within the 7-day window.

Here is sample output to verify correctness:

+-----------+------+---------------+-------------+
|   Date    | Data | Running Total | 7-day total |
+-----------+------+---------------+-------------+
| 1/4/2015  |    5 |             5 |           5 |
| 1/5/2015  |    3 |             8 |           8 |
| 1/9/2015  |    1 |             9 |           9 |
| 1/11/2015 |    9 |            18 |          13 |
| 1/12/2015 |    4 |            22 |          14 |
| 1/13/2015 |    2 |            24 |          16 |
| 1/27/2015 |   64 |            88 |          64 |
+-----------+------+---------------+-------------+