How to Add an Average For Specified Rows in a Table

// This rule adds a new row to the table showing the average of 
// rows selected by the user. This is just a simple average, ie
// the sum of the values from the rows, divided by the number of
// rows.

// Calculate a custom average and add to bottom of table.
includeWeb('JavaScript Array Functions');
includeWeb('Table JavaScript Utility Functions');
includeWeb('JavaScript Utilities');

form.setSummary("Simple Average Select Rows - One Statistic");

if (table.rowLabels.length != uniqueElementsInArray(table.rowLabels).length)
form.ruleNotAppliable("there are some duplicate row labels. All labels must be unique")

// Set up user inputs
var stat_label = form.newLabel("Statistic to use for custom average: ");
var stat_drop_down = form.newComboBox("st", table.availableStatistics);
stat_drop_down.lineBreakAfter = true;
stat_drop_down.setDefault(table.availableStatistics[0]);

var new_row_text = form.newLabel("Label for new row: ");
var new_row_box = form.newTextBox("nrl");
new_row_box.lineBreakAfter = true;

var rows_to_average_text = form.newLabel("Rows to average:");
rows_to_average_text.lineBreakAfter = true;
var row_selection = form.newComboBox("brb", table.rowLabels);
row_selection.setDefault(table.rowLabels[0]);
row_selection.lineBreakAfter = true;

var control_array = [stat_label, stat_drop_down, new_row_text, new_row_box, rows_to_average_text, row_selection];
form.setInputControls(control_array);

var row_label_options = [""].concat(table.rowLabels);

// Selection of rows to average
var rows_to_average = [];
var last_selection = row_selection.getValue();
var counter = 1;
var is_pm_next = true;
while (last_selection != "") {
rows_to_average.push(last_selection);
row_label_options = difference(row_label_options, rows_to_average);
var new_control = form.newComboBox("br" + counter, row_label_options);
new_control.lineBreakAfter = true;
new_control.setDefault("");
is_pm_next = true;
counter ++;
control_array.push(new_control);
form.setInputControls(control_array);
last_selection = new_control.getValue();
}

form.setInputControls(control_array);

var stat_to_use = stat_drop_down.getValue();

// Generate an array of the rows to exclude from the calculation of the sum
// for the custom average

var row_labels = table.rowLabels;
var row_indices_to_average = rows_to_average.map(function (label) { return row_labels.indexOf(label); });

// Add a new row at the bottom of the table
insertRowAfterComplete(table.numberRows - 1, new_row_box.getValue());

// Calculate the average for each Column
var values = table.get(stat_to_use);
for (var col = 0; col < table.numberColumns; col++) {
var sum = 0;
var count = 0;
row_indices_to_average.forEach(function (row) {
 if(!isNaN(values[row][col])){
sum += values[row][col];
count ++;
}
})

// Set custom average in last row
values[table.numberRows - 1][col] = sum / count;
}
table.set(stat_to_use, values);

4. Press the Play button > Close.

5. Change the Statistic to use for the custom average if different to the default selection.

6. Set the Label for the new row.

7. Under Rows to average, in each drop-down select the labels of the rows to include in the average calculation. Here, we have selected all 3 Coke row labels.

8. Press OK.