| with {base} | R Documentation |
Evaluate an R expression in an environment constructed from data, possibly modifying the original data.
with(data, expr, ...) within(data, expr, ...)
data |
data to use for constructing an environment. For the
default |
expr |
expression to evaluate. |
... |
arguments to be passed to future methods. |
with is a generic function that evaluates expr in a
local environment constructed from data. The environment has
the caller's environment as its parent. This is useful for
simplifying calls to modeling functions. (Note: if data is
already an environment then this is used with its existing parent.)
Note that assignments within expr take place in the constructed
environment and not in the user's workspace.
within is similar, except that it examines the environment
after the evaluation of expr and makes the corresponding
modifications to data (this may fail in the data frame case if
objects are created which cannot be stored in a data frame), and
returns it. within can be used as an alternative to
transform.
For with, the value of the evaluated expr. For
within, the modified object.
evalq, attach, assign,
transform.
require(stats); require(graphics)
#examples from glm:
## Not run:
library(MASS)
with(anorexia, {
anorex.1 <- glm(Postwt ~ Prewt + Treat + offset(Prewt),
family = gaussian)
summary(anorex.1)
})
## End(Not run)
aq <- within(airquality, { # Notice that multiple vars can be changed
lOzone<-log(Ozone)
Month<-factor(month.abb[Month])
cTemp <- round((Temp - 32) * 5/9, 1) # From Fahrenheit to Celsius
rm(Day, Temp)
})
head(aq)
with(data.frame(u = c(5,10,15,20,30,40,60,80,100),
lot1 = c(118,58,42,35,27,25,21,19,18),
lot2 = c(69,35,26,21,18,16,13,12,12)),
list(summary(glm(lot1 ~ log(u), family = Gamma)),
summary(glm(lot2 ~ log(u), family = Gamma))))
# example from boxplot:
with(ToothGrowth, {
boxplot(len ~ dose, boxwex = 0.25, at = 1:3 - 0.2,
subset = (supp == "VC"), col = "yellow",
main = "Guinea Pigs' Tooth Growth",
xlab = "Vitamin C dose mg",
ylab = "tooth length", ylim = c(0,35))
boxplot(len ~ dose, add = TRUE, boxwex = 0.25, at = 1:3 + 0.2,
subset = supp == "OJ", col = "orange")
legend(2, 9, c("Ascorbic acid", "Orange juice"),
fill = c("yellow", "orange"))
})
# alternate form that avoids subset argument:
with(subset(ToothGrowth, supp == "VC"),
boxplot(len ~ dose, boxwex = 0.25, at = 1:3 - 0.2,
col = "yellow", main = "Guinea Pigs' Tooth Growth",
xlab = "Vitamin C dose mg",
ylab = "tooth length", ylim = c(0,35)))
with(subset(ToothGrowth, supp == "OJ"),
boxplot(len ~ dose, add = TRUE, boxwex = 0.25, at = 1:3 + 0.2,
col = "orange"))
legend(2, 9, c("Ascorbic acid", "Orange juice"),
fill = c("yellow", "orange"))