merger <- cbind(as.character(Date),weather1$High,weather1$Low,weather1$Avg..High,weather1$Avg.Low,sale$Scanned.Movement[a])
After cbind
the data, the new DF has column names automatically V1
, V2
......
I want rename the column by
colnames(merger)[,1] <- "Date"
but failed. And when I use merger$V1
,
Error in merger$V1 : $ operator is invalid for atomic vectors
Try:
colnames(merger)[1] <- "Date"
Here is a simple example:
a <- 1:10
b <- cbind(a, a, a)
colnames(b)
# change the first one
colnames(b)[1] <- "abc"
# change all colnames
colnames(b) <- c("aa", "bb", "cc")
you gave the following example in your question:
colnames(merger)[,1]<-"Date"
the problem is the comma: colnames() returns a vector, not a matrix, so the solution is:
colnames(merger)[1]<-"Date"
If you pass only vectors to cbind()
it creates a matrix, not a dataframe. Read ?data.frame
.
A way of producing a data.frame
and being able to do this in one line is to coerce all matrices/data frames passed to cbind
into a data.frame while setting the column names attribute using setNames
:
a = matrix(rnorm(10), ncol = 2)
b = matrix(runif(10), ncol = 2)
cbind(setNames(data.frame(a), c('n1', 'n2')),
setNames(data.frame(b), c('u1', 'u2')))
which produces:
n1 n2 u1 u2
1 -0.2731750 0.5030773 0.01538194 0.3775269
2 0.5177542 0.6550924 0.04871646 0.4683186
3 -1.1419802 1.0896945 0.57212043 0.9317578
4 0.6965895 1.6973815 0.36124709 0.2882133
5 0.9062591 1.0625280 0.28034347 0.7517128
Unfortunately, there is no for data frames that returns the matrix after the column names, however, there is nothing to stop you from adapting the code of setColNames
function analogous to setNames
setNames
to produce one:
setColNames <- function (object = nm, nm) {
colnames(object) <- nm
object
}
See this answer, the magrittr
package contains functions for this.
If you offer cbind
a set of arguments all of whom are vectors, you will get not a dataframe, but rather a matrix, in this case an all character matrix. They have different features. You can get a dataframe if some of your arguments remain dataframes, Try:
merger <- cbind(Date =as.character(Date),
weather1[ , c("High", "Low", "Avg..High", "Avg.Low")] ,
ScnMov =sale$Scanned.Movement[a] )
It's easy just add the name which you want to use in quotes before adding vector
a_matrix <- cbind(b_matrix,'Name-Change'= c_vector)
Source: Stackoverflow.com