getting "PC1" insted of variable name in principal component analysis - r

Question

I have some data that looks like this:
head(data)
net1re net2re net3re net4re net5re net6re
24 3 2 1 2 3 3
33 1 1 1 1 1 2
30 3 1 1 1 1 3
22 2 1 1 1 1 1
31 3 2 1 1 1 2
1 2 1 1 1 1 2
I'm running principal component analysis as follows:
library(psych)
fit <- principal(data[,1:6], rotate="varimax")
data$friendship=fit$scores
This creates the variable "friendship" which I can call on the console:
> colnames(data)
[1] "net1re" "net2re" "net3re" "net4re" "net5re"
[6] "net6re" "friendship"
But when I want to view my data, instead of the variable name I get "PC1":
> head(data)
net1re net2re net3re net4re net5re net6re PC1
24 3 2 1 2 3 3 1.29231531
33 1 1 1 1 1 2 -0.68448111
30 3 1 1 1 1 3 0.02783916
22 2 1 1 1 1 1 -0.67371031
31 3 2 1 1 1 2 0.10251282
1 2 1 1 1 1 2 -0.44345075
This becomes a major trouble because I need to repeat that with diffrent variables and all the results get "PC1".
Why is this happening and how can I assign the variable name instead of "PC1".
Thanks

Answer 1

This unusual effect appears becausefit$scores is a matrix:
str(data)
#'data.frame': 6 obs. of 7 variables:
# $ net1re : int 3 1 3 2 3 2
# $ net2re : int 2 1 1 1 2 1
# $ net3re : int 1 1 1 1 1 1
# $ net4re : int 2 1 1 1 1 1
# $ net5re : int 3 1 1 1 1 1
# $ net6re : int 3 2 3 1 2 2
# $ friendship: num [1:6, 1] 1.1664 -1.261 0.0946 -0.5832 1.1664 ...
# ..- attr(*, "dimnames")=List of 2
# .. ..$ : chr "24" "33" "30" "22" ...
# .. ..$ : chr "PC1"
To get the desired result, you can use
data$friendship=as.vector(fit$scores)
or
data$friendship=fit$scores[,1]
In either case, the output will be:
data
# net1re net2re net3re net4re net5re net6re friendship
#24 3 2 1 2 3 3 1.16635312
#33 1 1 1 1 1 2 -1.26098965
#30 3 1 1 1 1 3 0.09463653
str(data)
#'data.frame': 6 obs. of 7 variables:
# $ net1re : int 3 1 3 2 3 2
# $ net2re : int 2 1 1 1 2 1
# $ net3re : int 1 1 1 1 1 1
# $ net4re : int 2 1 1 1 1 1
# $ net5re : int 3 1 1 1 1 1
# $ net6re : int 3 2 3 1 2 2
# $ friendship: num 1.1664 -1.261 0.0946 -0.5832 1.1664 ...