You can define certain data manipulation functions and create new derived data in the displays. The convertData attribute of a display takes the form of:

{{display_linechart   
convertData="func1(args); func2(args);"
}}

Where convertData can be any number of ";" delimited functions. The available functions are:

Replace:

convertData="replace(fields=field_ids, pattern=,with=);"

TBD:

convertData="roundDate(round=hour|day|week|month|year);"

TBD:

filterDate(one of month=0);

TBD:

groupTime(field=field to group time on);

Merge rows:

mergeRows(keyFields=f1_comma_f2, operator=count|sum|average, valueFields=);

Add percent increase:

addPercentIncrease(replaceValues=false);

Calculate # days to double:

doublingRate(fields=f1\\,f2, keyFields=f3);

Add a fixed value:

addFixed(id=field_name, value=3700,type=double);

TBD:

accum(fields=);

TBD:

mean(fields=);

Uniquify rows:

unique(groupFields=f1\\,f2,valueField=);

Count uniques:

count(field=,sort=true);

Unfurl:

unfurl(headerField=field to get header from,uniqueField=e.g. date,valueFields=);

Rotate data:

rotateData(includeFields=true,includeDate=true,flipColumns=true);

Prune where fields are all NaN:

prune(fields=);

Scale and offset:

accum(scale=1,offset1=0,offset2=0,unit=,fields=);

where we scale the value as:
(value + offset1) * scale + offset2

You can also specify your own function with the derived convertData. For example, lets say you have data with values a and b and you want to add a new field to the data "a+b". To do this simply specify a convertData attribute:

{{display_linechart   fields="a_and_b"
convertData="derived(field=a_and_b, function=return a+b)"}}

The derived function takes a field name and a function that is applied to each record in turn.

A more complicated example is below. Here we are using a separately defined Javascript function to take a dataset that contains a "discharge" field which is cubic feet/second of water flow and calculate both a volume for each record time step as well as a running total. The display has a convertData attribute. This has a "fields" attribute which is a comma separated list of field names (note the escaped comma). If just one field you can also use a "field" attribute. This also has an optional "units" attribute. The function needs to be of the form: "return function_name(args)".

{{display_linechart
convertData="derived(fields=volume\,total_volume, units=acre feet\,acre feet, function=return calculateVolume(args));" 
entry=76c9e5a1-2875-4a08-9b45-d106e9b1f341   fields="volume,total_volume"}}

To define the javascript you can include javascript inline with the "+javascript/-javascript" wiki tag. This gets called for every record. The args object contains:

{
values:{},
recordIndex:rowIdx,
record:record
};

Where:

• values - is a map holding the record values, e.g. values[1], values[2]
• state - an object that exists
• recordIndex
• record - the data record

The args object also is the same object call by call so you can store other values in it. Here is the calculateVolume function:

+javascript
function calculateVolume(args) {
    if(!args.lastDate) {
    //if first record then initialize date and total_volume
        args.lastDate = args.record.getDate();
        args.total_volume = 0;
        return [0,0];
    }
    //calculate the volume for this record
    let seconds = (args.record.getDate().getTime()-args.lastDate.getTime())/1000;
    args.lastDate = args.record.getDate();
    let discharge = args.values['discharge'];
    if(isNaN(discharge)) return NaN;
    let volume = discharge*seconds/43560;
    args.total_volume+=volume;
    return [volume,args.total_volume];
}

-javascript