Finding index using switch case statement in javascript

Question

I'm using Pentaho(ETL) tool to achieve the output using a javascript component which accepts javascript code to achieve the desired transformation.The following table is imported into pentaho from a .csv file(source file). For example this is my table structure

 +--------+--------+--------+
| RLD    | MD     | INC    |
+--------+--------+--------+
|      0 |   3868 | 302024 |
|  53454 |   7699 | 203719 |
| 154508 |    932 |  47694 |
| 107547 |  36168 |  83592 |

I want to use a script which would give me the max_value and its index number, such that my output would look like Output Table

 +--------+--------+--------+-----------+-----------+
    | RQD    | MT     | IZC    | max_value | max_index |
    +--------+--------+--------+-----------+-----------+
    |      0 |   3868 | 302024 |    302024 |         3 |
    |  53454 |   7699 | 203719 |   203719  |         3 |
    | 154508 |    932 |  47694 |    154508 |         1 |
    |    456 |  107547|  83592 |    107547 |         2 |

To get the max value from rows I have used

var max_value = Math.max(RQD,MT,IZC);
println(max_value);

I tried to get their index using the following script

var max_index = switch (Math.max(RQD,MT,IZC))
           {
           case "RQD":document.write("1")
           case "MT":document.write("2")
           case "MT":document.write("3")
         default:document.write("0") 

       }

How can I get the desired result in the form of javascript data structure? Any help would be much appreciated.Thanks

Please explain what is inside the *RQD*,*MT* and *IZC* variables. — Mario Santini, Aug 04 '16 at 08:26
all variable contains numbers(integers) stored in tabular format — Deepesh, Aug 04 '16 at 08:27
Your switch is wrong as you should put a string not the max value. You should have a structure and check the max value by yourself, to save the column and the index. — Mario Santini, Aug 04 '16 at 08:31
You should add how you get the variables with the record values. As I see you post just how you handle the data of a single record. And more, you didn't say how the results should appear: an html table? a javascript data structure? Something else? — Mario Santini, Aug 04 '16 at 10:07
please update your question with this infos. That made things easiest for who want to help. — Mario Santini, Aug 04 '16 at 11:13

Bamieh · Answer 1 · 2016-08-04T09:08:28.237

0

There are several issues with your code, lets solve them!

Use breaks: you must use breaks in order to avoid the switch moving to cases below its match.
switch cases do not return a value like functions, you cannot use a switch return to define a variable, you need to define the variable inside the switch case.
Math.max does not return the name of its maximum variable, instead it returns the maximum number from its given parameters.

to solve this issue, i would not use a switch case with math.max to be honest, however to answer your question:

var tableArray = [RQD,MT,IZC];
var maxIndex = tableArray.indexOf(Math.max.apply(null, arr));
if(maxIndex > -1) document.write(maxIndex+1);

i used +1 because you have your index in the example table starting from 1 instead of 0.
the way the array is sorted should match the way the table is sorted per raw.

edited Aug 04 '16 at 09:08

answered Aug 04 '16 at 08:39

Bamieh

10,358
4
31
52

Edits have been made to post,please check – Deepesh Aug 04 '16 at 09:05
removed the println bullet point, try my code it should solve your case without a switch case. – Bamieh Aug 04 '16 at 09:09
That's a weird behaviour of Kettle. Apparently, output of functions are not instanceof Number, while array elements injected from Kettle are Numbers. Following code works for some reason: `var tableArray = [RQD, MT, IZC].map(Number); var maxResult = Math.max.apply(null, tableArray); var maxIndex = tableArray.indexOf(maxResult);` – Andrei Luksha Aug 11 '16 at 16:53

score 0 · Answer 2 · edited Aug 04 '16 at 08:50

0

var list = [
{RLD:0,
MD:3868,
INC:302024
},
{RLD:53454,
MD:7699,
INC:203719
},
{RLD:154508,
MD:932,
INC:47694
},
{RLD:107547,
MD:36168,
INC:83592
},
];

list = list.map(function(item){
  var keys = Object.keys(item);
  item.max_value = item[keys[0]];
  item.max_index = '';
  for(var i = 1, l = keys.length; i < l; i++) {
    var key = keys[i];
    var keyValue = item[key];
    if (item.max_value < keyValue){
      item.max_value = keyValue;
      item.max_index = key;
    }
  }
  return item;
})

edited Aug 04 '16 at 08:50

Bamieh

10,358
4
31
52

answered Aug 04 '16 at 08:40

Mohankumar Balakrishnan

65
4

Edits have been made to post,please check – Deepesh Aug 04 '16 at 09:06
,the variable values are not be be entered manually, can we not just consider the column only. – Deepesh Aug 04 '16 at 09:13

score 0 · Answer 3 · answered Aug 04 '16 at 11:52

First of all you could not solve this problem with a switch statement.

In a javascript switch you should provide a value that is one of the followed case(s), otherwise the switch will go to the default if defined.

Your problem seems to be to find out the higher value of 3 columns and print out, the colums row by row adding a column with the max value and the index of the column where you found it.

So for example on the row:

1, RLD : 0

2, MD : 3868

3, INC : 302024

In this case the higher value is INC with the column index 3.

If you have just the variables with the number values, you could do nothing more than something like this:

function getMaxValueRow (RLD, MD, INC) {

    var max_value = RLD;
    var max_index = 1;

    if (MD > max_value) {
        max_value = MD;
        max_index = 2;
    }

    if (INC > max_value) {
        max_value = INC;
        max_index = 3;
    }

    return [RLD, MD, INC, max_value, max_index];
}

You could return an object too like this:

retrun {
    'RQD': RLD,
    'MT': MD,
    'IZC': INC,
    'max_value': max_value,
    'max_index': max_index
}

Finding index using switch case statement in javascript

3 Answers3