R help - Oct 2002 - barplot + plot

Dear all,
I've got another question,
By default barplot and plot seem to produce slightly different y-axis.
The problem I've got is when using a mix figure with both, barplot and
plot. For example:

barplot(1:5, ylim=c(0, 6))
par(new= T)
plot(1:5, 9:5, type="b", axes=FALSE, ylim=c(0,9))
axis(4)
box()

note that both plots (barplot and plot) should start at 0, but the exact
starting at 0 is only produced with barplot but not with plot.
Is there a way to make the two axes more coherent, that is both starting
at the exact 0 or both starting like the plot?

Thanks a lot for any suggestion

Juli

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> -----Original Message-----
> Dear all,
> I've got another question,
> By default barplot and plot seem to produce slightly different y-axis.
> The problem I've got is when using a mix figure with both, barplot and
> plot. For example:
> 
> barplot(1:5, ylim=c(0, 6))
> par(new= T)
> plot(1:5, 9:5, type="b", axes=FALSE, ylim=c(0,9))
> axis(4)
> box()
> 
> note that both plots (barplot and plot) should start at 0, but the
exact
> starting at 0 is only produced with barplot but not with plot.
> Is there a way to make the two axes more coherent, that is both
starting
> at the exact 0 or both starting like the plot?
> 
> Thanks a lot for any suggestion
> 
> Juli
Juli,

The difference is in the way that barplot() and plot() draw the style of
axes by default.

In barplot(), which you call first, it sets par(yaxs = "i") explicitly
in the code.

Unless you change it, plot() uses the default parameter value of
par(yaxs = "r"), which draws a different style of axis.

If you add:

par(yaxs = "i") before your plot(...) line, you will get a consistent
0
starting point.

See ?par and scroll to par(xaxs), which describes the style of axes
available for both x and y.

Thus, your example code should look like:

barplot(1:5, ylim=c(0, 9))
par(new= T)
par(yaxs = "i")
plot(1:5, 9:5, type="b", axes=FALSE, ylim=c(0,6))
axis(4)
box()

I presume that you explicitly want the y axis ranges to be different.
If not, be sure to set ylim to the same values.

HTH.

Marc Schwartz



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> -----Original Message-----
>
> SNIP
>
> Thus, your example code should look like:
> 
> barplot(1:5, ylim=c(0, 9))
> par(new= T)
> par(yaxs = "i")
> plot(1:5, 9:5, type="b", axes=FALSE, ylim=c(0,6))
> axis(4)
> box()
> 
A quick clarification.  I just noted that I reversed the ylim settings
from Juli's original example code.

Of course the example code should be:

barplot(1:5, ylim=c(0, 6))
par(new= T)
par(yaxs = "i")
plot(1:5, 9:5, type="b", axes=FALSE, ylim=c(0,9))
axis(4)
box()

Marc Schwartz
<In need of more coffee this morning>



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