Combining different graph types
It is perfectly legal to add several different plot types to the same
graph. It is therefore possible to mix line plots with (for example)
filled bar graphs. What you should keep in mind doing this is the
order in which these plots are stroked to the image since a later
stroke will overwrite a previous one. All plots are stroked in the
order you add them, i.e. the first plot added will be stroked
first. You can therefore control which plot is placed in the
background and which one is placed in the foreground by the order you
add them to the plot.
To start simple we just mix a filled line plot with a non-filled line
plot as the following example shows.
Figure 1: Mixing filled and non-filled line plots in the
same graph [src]
Let's now go to something a little bit more complicated. How to mix
bar and line graphs. Let's just take one of our previous bar graphs
and add a line plot to it and see what happens.
Figure 2: Adding a line to a bar graph [src] Not too bad. But we can't see the line so we change the order in which
we add the lines to the graph and sees waht happens.
Figure 3: Adding a line to a bar graph, in different orderv2 [src]
If you want the line to be aligned in the center of the bars you will
have to switch to a linear (or integer) scale.
As the following example will show
Figure 4: Using a linear scale [src]
Note: In this example we also have illustrated the
fact that you can add text labels to a linear (or integer)
scales as well.
As a final example we show how you can combine a scatter plot and
a line plot which could be used to illustrate a regression line
fitting.
Figure 5: Combining a scatter plot and a line plot [src]