Group by date in a visual

[BenjaminCoe1440]

I have a chart which monitors meter readings (below; blue). There are numerous readings per date (spread out over 48 readings; half-hourly) and the dataset that I am using has a row for each reading. 

Is it possible group in the chart by day without having to create a separate table with one row per date?

[MarcoWedel]

Do you mean to aggregate (in this case sum) all 48 half-hour readings to get one single value per day?

In this case I think you just have to replace your dimension with the ReportDate you already seem to have
(although your dimension axis is already labeled as "ReportDate", yet it seems to use timestamps rather than dates?!?)