Extract Identifier from Principal Component Analysis with Missing Data in R

Extract Identifier from Principal Component Analysis with Missing Data in R

I am conducting a principal component analysis in R on vectors with
missing data. I want to extract the score from the principal component and
match the values with the observations that are not missing in the
original frame but I can't figure out how to extract and match on the
right identifiers. For example:
x1 <- c(1,2,3,NA, 5,6,7)
x2 <- c(7,NA,6,NA, 4,3,2)
frame <- cbind(x1,x2)
pca_ob<- princomp(~frame)
pca_ob$score[,1]
This produces the following output:
1 3 5 6 7
4.273146 2.104705 -0.715732 -2.125950 -3.536168
I would like to bind pca_ob$score[,1] with the original frame based on the
identifiers and fill the rest in with NAs. Any thoughts? Thanks.