Question

Table1 <- data.frame(CName  = c("aa", "bb", "cc", "dd"),
                     number = c("X11", "X22", "X33", "X44"))

Table2 <- data.frame(PName = c("zz", "yy", "xx", "ww"),
                     "X11" = c(5, 6, 3, 5),
                     "X22" = c(7, 5, 4, 3),
                     "X44" = c(9, 9, 1, 1))

I got Table1

  CName number
1    aa    X11
2    bb    X22
3    cc    X33
4    dd    X44

I got Table2

  PName X11 X22 X44
1    zz   5   7   9
2    yy   6   5   9
3    xx   3   4   1
4    ww   5   3   1

I want to get two files:

(1) by matching CName of Table 1 to column Heading of Table 2, I want to have a new table like this:

ResultsTable1

  PName  aa  bb  dd
1    zz   5   7   9
2    yy   6   5   9
3    xx   3   4   1
4    ww   5   3   1

I also wants to know the what is missing, i.e. In this example, cc is missing in Table2, so it is not matched.

ResultTable2

Table1:  
Table2: cc

Are there any effective way of doing these?

Answer 1

Set the column names other than the first column of Table2 based on the values in Table1

colnames(Table2)[-1] <- as.character(Table1[Table1[["number"]] %in% colnames(Table2)[-1], "CName"]) 
Table2
#  PName aa bb dd
#1    zz  5  7  9
#2    yy  6  5  9
#3    xx  3  4  1
#4    ww  5  3  1

This will show what’s in Table1[["CName"]] that’s not in the new colnames of Table2

as.character(Table1[["CName"]][!Table1[["CName"]] %in% colnames(Table2)[-1]])
#[1] "cc"

And this will show what’s in the new colnames of Table2, but not in Table1[["CName"]]

as.character(colnames(Table2)[-1][!colnames(Table2)[-1] %in% Table1[["CName"]]]) 
#character(0)

Perhaps some simple examples of the %in% syntax will help (note that this is documented in ?match and that A %in% B is just an alternate syntax for match(A, B, nomatch=0) > 0

A <- c("A", "B", "D", "E")
B <- c("B", "C", "D")
A %in% B
#[1] FALSE  TRUE  TRUE FALSE
!A %in% B
#[1]  TRUE FALSE FALSE  TRUE
A[A %in% B]
#[1] "B" "D"
A[!A %in% B]
#[1] "A" "E"
B[B %in% A]
#[1] "B" "D"
B[!B %in% A]
#[1] "C"

For your data, I used as.character to convert from factor to character