Graphics Reference
In-Depth Information
Solution
Define a new wrapper function around your curve function, and replace out-of-range values with
NA
(), as shown in
Figure 13-6
:
# Return dnorm(x) for 0 < x < 2, and NA for all other x
dnorm_limit
<-
function
function
(x) {
y
<-
dnorm(x)
y[x
<
0
|
x
>
2
]
<-
NNA
return
return
(y)
}
# ggplot() with dummy data
p
<-
ggplot(data.frame(x
=
c(
-3
,
3
)), aes(x
=
x))
p
+
stat_function(fun
=
dnorm_limit, geom
=
"area"
, fill
=
"blue"
, alpha
=
0.2
)
+
stat_function(fun
=
dnorm)
Figure 13-6. Function curve with a shaded region
Remember that what gets passed to this function is a vector, not individual values. If this function
operated on single elements at a time, it might make sense to use an
if/else
statement to decide
