Evaluating an Expression in R Programming – with() and within() Function
Last Updated :
01 Jun, 2020
with()
function in R programming evaluates the expression in an environment constructed locally by the data and does not create a copy of the data.
Syntax: with(data, expr)
Parameters:
data represents dataset to be used
expr represents formula or expression to be evaluated
Example 1:
df < - list ( "x1" = c( 1 , 2 , 3 ),
"x2" = c( 4 , 5 , 6 ),
"x3" = c( 7 , 8 , 9 ))
with(df, x1 + x2 + x3)
|
Output:
[1] 12 15 18
Example 2:
with(mtcars, mean(mpg + cyl + disp))
|
Output:
[1] 257
within() Function
within()
function in R programming evaluates the expression in a locally created environment and modifies the copy of the data unlike with()
function.
Syntax: within(data, expr)
Parameters:
data represents dataset to be used
expr represents formula or expression to be evaluated
Example 1:
df < - list ( "x1" = c( 1 , 2 , 3 ),
"x2" = c( 4 , 5 , 6 ))
within(df, x3 < - x1 + x2)
|
Output:
$x1
[1] 1 2 3
$x2
[1] 4 5 6
$x3
[1] 5 7 9
Example 2:
aq < - within(airquality, {
newOzone < - log(Ozone)
cTemp < - round ((Temp - 32 ) * 5 / 9 , 1 )
})
head(aq)
|
Output:
Ozone Solar.R Wind Temp Month Day cTemp newOzone
1 41 190 7.4 67 5 1 19.4 3.713572
2 36 118 8.0 72 5 2 22.2 3.583519
3 12 149 12.6 74 5 3 23.3 2.484907
4 18 313 11.5 62 5 4 16.7 2.890372
5 NA NA 14.3 56 5 5 13.3 NA
6 28 NA 14.9 66 5 6 18.9 3.332205
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