Sum values in an array

General
1

Can someone please give me a correction on this flow...I am trying to sum the values in this example array. Thanks,

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2

Here's the document Array.prototype.reduce() - JavaScript | MDN

And here's how it applies to your case

var testtable = [];
testtable[0] = 32455.6;
testtable[20] = 31399.6;
testtable[40] = 31299.5;
testtable[60] = 31280.0;
testtable[80] = 31270.0;
testtable[100] = 31200.0;
testtable[120] = 31155.0;
testtable[140] = 31100.0;
testtable[160] = 31075.0;
testtable[180] = 31000.0;
testtable[200] = 30900.0;
testtable[220] = 30800.0;
testtable[240] = 30700.0;
testtable[260] = 30600.0;
testtable[280] = 30550.0;
testtable[300] = 30485.0;
testtable[320] = 30400.0;
testtable[340] = 30300.0;
testtable[359] = 30100.0;

var sum = testtable.reduce((a, b) => a + b, 0)

msg.payload = sum;
return msg;
3

Hi the answer above is the best way.

But your for loop is all messed up, it should have 3 elements.
The array you created has a length of 360 as when adding to an array all missing indexes are added and given null values.
You then failed to call the function and give it a value.
Also in your function you name the incoming value to testtable but then refer to it as array.
here is a working example so you can learn more how for loops work and testing values, in this example to confirm it is a number.

var testtable = [];
testtable[0] = 32455.6;  
testtable[20] = 31399.6;
testtable[40] = 31299.5;
testtable[60] = 31280.0;
testtable[80] = 31270.0;
testtable[100] = 31200.0;
testtable[120] = 31155.0;
testtable[140] = 31100.0;
testtable[160] = 31075.0;
testtable[180] = 31000.0;
testtable[200] = 30900.0;
testtable[220] = 30800.0;
testtable[240] = 30700.0;
testtable[260] = 30600.0;
testtable[280] = 30550.0;
testtable[300] = 30485.0;
testtable[320] = 30400.0;
testtable[340] = 30300.0;
testtable[359] = 30100.0; //this creates an array 360 in length 300+ null values
msg.payload = testtable;
node.send(msg);
function sumArray(array) {
var sum = 0;
  for (var index = 0; index < array.length; index++){ // 3 values in a for loop
        if(!isNaN(array[index])){ // check if value is a number
            sum += array[index]   // Add number on each iteration
        }
      }
  return sum;
}

msg.payload = sumArray(msg.payload)  // send value to function
return msg;
1 Like
4

ok i got it. thanks for your help..

5

Hi I'm having kind of the same problem I have an array im wanting to sum, value [0] . [1] . [2] . I want to add 0 , 1 and 2 together but when I use function
Var one = msg payload [0];
Var two = msg.payload [1];
Var two = msg.payload [2];

Var total = one + two + three;
Msg.payload = total;

The result im getting is the values of the arrays next to each other ? If I replace the +with* the numbers are multiplied and the correct answer is resulting.
Sorry if I sound stupid but my background is plc ladder programming and I'm just breaking in to java.

Cheers Tommy

6

That suggests the values in the array are strings. Wrap the values with Number()

E.g.

var one = Number(msg payload[0]);
7

Hi @Steve-Mcl
Thanks mate that worked a treat your a gent.

Cheers Tommy

8

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