You need to swap the datasets, so that file with 400K records, that you wish to filter/analyse based on the categories is your main dataset, while buffer zones are in the overlying dataset.
You start with 2 files, here .csv format, that contain granular data and target areas.

Start with a new file and drag the dataset with 260 points onto your DataManager. Then add a Geometric Buffer block and configure the parameters, such as radius around the markers and load the data into Omniscope. Save the file.


In a new file load into Omniscope the second source, that contains 400K records with category/type values.
In the DataExplorer space add the Map and Pivot view, configuring the lat/long and X/Y fields.
Drag the BufferZones iok file directly onto the Map view, creating an overlay. In the Map view, under the Mode menu enable the option 'Select by overlay area' and set the data subset in the Pivot view to 'Selected data'. This should allow you to pivot the granular data covered by the buffer - one or multiple selection is possible.
In a file below we're using similar scenario, looking at school locations around UK, and using overlaying data for school dinner suppliers, who can cater for those in a 50km radius.

Hi Paola

This is perfect and just the example I was creating. There is just the final piece I am missing though that will make this ver powerful.

I was wondering if we can appy a geometric buffer to the pivot table, so that supplier appears on the rows of the Pivot Table and the number of outlets that fall within their catchment area. I inderstand that some areas (if you have a lot) will overlap and the counts will be duplicated - not sure if this is possible though.

In essence, its a table representation of the map that we are after?

Understand that this might not be possile.

Cheers

Danny

You could add a field [Supplier] to your main dataset. If a customer can have more than one supplier, then you can format it as a tokenised field (to enable it to store multiple values).
In any case, by clicking on a buffer zone, you've already picked a supplier X, so all the records in the newly-created Pivot are data points that belong to that supplier...

If you use both the buffer as Paola has shown, you then use the Geometric Filter operation. This will give you a new areas field which tags on each postcode given here if they fall into any of those areas.

You will get fewer records before as it will filter out those records that do not lie in any of those buffers. Just re-add those in to the main data set using a merge join against an unique identifier field.