Value rather than category x-axis on combo chart

[willbowe]

I have a combo chart with a scatter and a line, in which I would like to set minimum and maximum bounds for the x-axis in the same way I can for the y-axis. However, the combo chart insists on treating the x-axis as a "category" axis rather than a "value" axis, as it would in a line or bar chart. Consequently, the only options available for the x-axis are "text", "date" and "automatically select based on data", none of which give me what I want (which is simply to have markers on the x-axis for 0, 5, 10, 15, 20 and 25, which can very easily be done on a value axis). Is there any way around this?

[MrShorty]

Because scatter and line charts are so similar (really only differing in the nature of the horizontal axis), I wonder why you are making a combination line and scatter chart? I wonder because I think the specific solution probably depends on exactly why you need to combine both line and scatter charts together.

[willbowe]

The idea is for the line to be x = y, so it is clearly apparent which points have x > y and which vice-versa. My first approach was to just have a scatter plot and use a trendline to get the x = y line, but I'm not satisfied with this as the trendline appears on top of the scatter points rather than behind them. So alternative solutions to my problem might involve a) working out how to put a trendline in the background rather than the foreground, or b) any other means of having a diagonal line appear in a way that makes it look like one of the gridlines.

[Andy Pope]

Use a xyscatter chart and add a new series to draw the diaginal.
That series only needs 2 sets of points to describe bottom left and top right.

You will need to fix the axes min/max values if you want the line to go to the corners

[willbowe]

But doesn't that just create two new scatter plot points? What I want is a line connecting the two, which is why I tried a combo chart. When I did this though, it wouldn't let me treat the x-axis as if it were for a scatter plot rather than a line graph (i.e. as a value rather than category axis).

[Andy Pope]

Yes, but you can format the series to not have markers and for the line to be formatted the same as the other gridlines.

[willbowe]

Yep - there's your answer. Thank you!