Manipulation of Data Sets¶
Description¶
Like data frames, data.set objects have subset, unique, cbind, rbind,
merge methods defined for them.
The semantics are basically the same as the methods defined for data frames in the
base package, with the only difference that the return values are data.set
objects. In fact, the methods described here are front-ends to the corresponding methods
for data frames, which are constructed such that the “extra” information attached to
variables within data.set objects, that is, to item objects.
Usage¶
## S4 method for signature 'data.set'
subset(x, ...)
## S4 method for signature 'data.set'
unique(x, incomparables = FALSE, ...)
## S3 method for class 'data.set'
cbind(..., deparse.level = 1)
## S3 method for class 'data.set'
rbind(..., deparse.level = 1)
## S4 method for signature 'data.set,data.set'
merge(x,y, ...)
## S4 method for signature 'data.set,data.frame'
merge(x,y, ...)
## S4 method for signature 'data.frame,data.set'
merge(x,y, ...)
Arguments¶
-
x,y -
data.setobjects. On of the arguments tomergemay also be an object coercable into a data frame and the result still is adata.setobject. ...-
for
subset: a logical vector of the same length as the number of rows of thedata.setand, optionally, a vector of variable names (tagged asselect); forunique: further arguments, ignored; forcbind,rbind: objects coercable into data frames, with at least one being adata.setobject; formerge: further arguments such as arguments tagged withby,by.x,by.y, etc. that specify the variables by which to merge the data sets of data framesxandy. incomparables-
a vector of values that cannot be compared. See
unique. deparse.level-
an argument retained for reasons of compatibility of the default methods of
cbindandrbind.
Examples¶
ds1 <- data.set(
a = rep(1:3,5),
b = rep(1:5,each=3)
)
ds2 <- data.set(
a = c(3:1,3,3),
b = 1:5
)
ds1 <- within(ds1,{
description(a) <- "Example variable 'a'"
description(b) <- "Example variable 'b'"
})
ds2 <- within(ds2,{
description(a) <- "Example variable 'a'"
description(b) <- "Example variable 'b'"
})
str(ds3 <- rbind(ds1,ds2))
Data set with 20 obs. of 2 variables:
$ a: Itvl. item num 1 2 3 1 2 3 1 2 3 1 ...
$ b: Itvl. item int 1 1 1 2 2 2 3 3 3 4 ...
description(ds3)
a 'Example variable 'a''
b 'Example variable 'b''
ds3 <- within(ds1,{
c <- a
d <- b
description(c) <- "Copy of variable 'a'"
description(d) <- "Copy of variable 'b'"
rm(a,b)
})
str(ds4 <- cbind(ds1,ds3))
Data set with 15 obs. of 4 variables:
$ ds1.a: Itvl. item int 1 2 3 1 2 3 1 2 3 1 ...
$ ds1.b: Itvl. item int 1 1 1 2 2 2 3 3 3 4 ...
$ ds3.c: Itvl. item int 1 2 3 1 2 3 1 2 3 1 ...
$ ds3.d: Itvl. item int 1 1 1 2 2 2 3 3 3 4 ...
description(ds4)
ds1.a 'Example variable 'a''
ds1.b 'Example variable 'b''
ds3.c 'Copy of variable 'a''
ds3.d 'Copy of variable 'b''
ds5 <- data.set(
c = 1:3,
d = c(1,1,2)
)
ds5 <- within(ds5,{
description(c) <- "Example variable 'c'"
description(d) <- "Example variable 'd'"
})
str(ds6 <- merge(ds1,ds5,by.x="a",by.y="c"))
Data set with 15 obs. of 3 variables:
$ a: Itvl. item int 1 1 1 1 1 2 2 2 2 2 ...
$ b: Itvl. item int 1 4 3 2 5 1 4 3 2 5 ...
$ d: Itvl. item num 1 1 1 1 1 1 1 1 1 1 ...
# Note that the attributes of the left-hand variables
# have priority.
description(ds6)
a 'Example variable 'a''
b 'Example variable 'b''
d 'Example variable 'd''