2nd Y axis

There is a chart style that has two Y axes. By default it is a combination line and bar chart but you can do lines, bars, or areas. It is a category chart, not a scatter (true X-Y) chart.

There are no charts with two X axes nor is there a scatter chart with two Y or X axes. There are several ways to create such things. One way is to plot two separate charts and overlay them, removing the duplicated things from one of the charts (gridlines, for instance) , removing one set of axis labels, and using a table or text boxes to create the labels for the second axis.

Schrodinger,

To Badunit's list of things to do when you are overlaying charts, I would add: Manually set the Min and Max axis limits identically for both charts. You need to prevent the scales from being out of alignment.

Jerry

We often advise users, in special situations, to make a custom set of axis labels and use it in place of the defaults. The answer is the same in your case, but instead of placing the custom label (text box or table) on the right rather than on the left.

Jerry

There is a Chart Type called, "2-Axis." You can select it either by Format>Chart>Chart Type>2-Axis or by clicking on this chart type icon:

Hi Schrodinger,

Your original question:

to plot 2 sets of data pertaining to one X axis.

This method does not add a 2nd Y axis, but it puts 2 sets of Y data on the one graph. It might be what you want.

The Table has a Header Row (for Labels X, Y1, Y2) but none of the data are in a Header Column (I think that is necessary for a scatter plot??)

Select the three Columns, choose Scatter from the Chart Button. Then with the scatter plot selected, click on the gear wheel at the top of the Table and choose Share X Values.

Regards,

Ian.

Message was edited by: Yellowbox. Select the three rows changed to: Select the three Columns

Badunit wrote:

.. By default it is a combination line and bar chart but you can do lines, bars, or areas. ..

how can i change the bars to lines?

btw, i'm impressed how Numbers picks the correct data sets for the two y-axes.

how does it do that? and how to edit that, if it was mistaken?