Hi
I stated that this can be done using a DataView, but I did not say that it
would be as clean as you would like, especially satisfying your request to
use the general existing weighted average function as is. If the
WeightedAverage function is indeed what you wrote (I did not see any
normalization there so I wasn't sure), you can indeed get the desired
outcome using first a DataView to create the weighted columns [2,5,6,7] (by
multiplying their value by the weight) and then applying the group call as
you did it where replacing the WeightedAverage with the sum function.
I agree that it would be more natural to have the syntax as you wrote it
available for this use case but currently it simply does not exist.
Here is a snippet of the code:
view = new google.visualization.DataView(table);
view.setColumns([
0,
1,
{calc: weightedColumn(2, 4), type: 'number'},
3,
4,
{calc: weightedColumn(5, 4), type: 'number'},
{calc: weightedColumn(6, 4), type: 'number'},
{calc: weightedColumn(7, 4), type: 'number'}]);
bySector = new google.visualization.data.group(view, [1],
[ {column:0, aggregation:AllSameOrMany, type:'string'}
,{column:2, aggregation:google.visualization.data.sum,type:'number'}
,{column:3, aggregation:google.visualization.data.sum,type:'number'}
,{column:4, aggregation:google.visualization.data.sum,type:'number'}
,{column:5, aggregation:google.visualization.data.sum,type:'number'}
,{column:6, aggregation:google.visualization.data.sum,type:'number'}
,{column:7, aggregation:google.visualization.data.sum,type:'number'}
]
);
function weightedColumn(dataColumnIndex, wightsColumnIndex) {
return function(dataTable, rowNum) {
return dataTable.getValue(rowNum, dataColumnIndex)
* dataTable.getValue(rowNum, weightsColumnIndex);
}
}
Best,
Viz Kid
On Wed, Jun 29, 2011 at 5:04 AM, NA <[email protected]> wrote:
> VIz Kid, can you post that example?
>
> On Jun 24, 9:58 pm, NA <[email protected]> wrote:
> > So can you present an example using DataView? I can't see a
> > straightforward way to do this, but I'll give you the benefit of the
> > doubt. Show me how you'd do the following:
> >
> > table has these columns:
> >
> > 0 1 2 3 4 5 6 7
> > id, sector, price, shares, weight, f1, f2, f3
> >
> > I want to aggregate this by sector. The aggregation functions for
> > price, f1, f2, and f3 is a weighted average. The aggregation for
> > shares and weight is a sum. The aggregation for id and sector is to
> > return the string "Many" if there are multiple values in that column,
> > or if all the entries are the same return that value.
> >
> > Such aggregation functions might look like:
> >
> > function WeightedAverage(q,w) {
> > var wsum = 0;
> > for (i=0;i<w.length;i++) {wsum+= w[i]*q[i];}
> > return wsum;
> >
> > }
> >
> > function AllSameOrMany(c) {
> > var r = c[0];
> > for (var i=0;i<c.length;i++) {if (r !=c[i]){return 'Many';}};
> > return r;
> >
> > }
> >
> > Note that the WeightedAverage function is a general function that
> > doesn't require the weight to always be in column 4. It also doesn't
> > know what Tables are. It's used in many places; its existence
> > predates the google visualization API. This is important for
> > reusability, maintainability, and interoperability across many
> > libraries.
> >
> > What I'd like to do is;
> >
> > bySector = new google.visualization.data.group(table,[1],
> > [ {column:0, aggregation:AllSameOrMany, type:'string'}
> > ,{column:[2,4],aggregation:WeightedAverage,type:'number'}
> > ,{column:3, aggregation:google.visualization.data.sum,type:'number'}
> > ,{column:4, aggregation:google.visualization.data.sum,type:'number'}
> > ,{column:[5,4], aggregation:WeightedAverage,type:'number'}
> > ,{column:[6,4], aggregation:WeightedAverage,type:'number'}
> > ,{column:[7,4], aggregation:WeightedAverage,type:'number'}
> > ]
> > );
> >
> > Since this syntax doesn't exist, can you show me how to do this with
> > google.visualization.data.group or with DataViews, without having to
> > create special versions of my aggregation functions?
> >
> > In my case, I used currying to wrap functions like WeightedAverage in
> > a way to accommodate the grouping and DataView APIs.
> >
> > But I'd like to learn a cleaner way of doing this.
> >
> > thanks,
>
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