I have occasionally recorded usage data from a metering system (water pumps or gas tank), with the first two columns below: (Date, reading)

DateTime meter_reading consumed time_diff daily_average_equivalent
7/2/12 9:00 AM 500 -
7/3/12 8:00 AM 512 12 (B3-B2) (A3-A2) (consumed/time diff)
7/7/12 5:00 PM 520 8 (B4-B3) (A4-A3)
7/14/12 8:30 AM 531 11 ... ...
7/27/12 9:30 AM 551 20
8/12/12 12:00 PM 600 49


I then calculated consumption (3rd col) and then can calculate time difference (4th), and daily average consumption equivalent (5th) to get comparable measures.

At this point I would like to draw a chart to ease reading.

I can easily do an X/Y graph with time scale and Column B.
I get the growing meter reading line (value never reducing).
This is fine but I would like to represent column C (kind of flatten down the rising line to delta values).
How can I do this?

I picked a column graph for column C, but I would like to show the consumed value NOT with a thin column in reading date, but with a wider flat area from previous to current reading (meaning that I assume the consumption was evenly distributed between the readings).
Is there a way to do this graph starting from data collected as above, without the need to create an expanded data table with each day by day interpolated values?

Thanks

Hi wittingdaprato,

Welcome to the forums.

I think I understand your problem. I would recommend a slightly different solution. I would make a regular Line chart, not a XY Line chart as you describe.

You do not need to create data points for an interpolation of each data point. With a line chart, if you change your Horizontal Axis from a Text Axis to a Date Axis, then Excel will plot your data points and if you expand the chart you can see each day even though it is not an acual data point.

Notice in the picture below that if you expand a Text Axis type of chart that the dates only show the 5 data points, but on the Date Axis type of chart, as I expand it, you can see each day.

Please let me know if this helps.

Steve=True