These notes explain how to move data between R and Excel and other Windows applications via the clipboard.
R has a function
writeClipboard that does what the name implies. However, the argument to
writeClipboard may need to be cast to a character type. For example the code
> x <- "hello world" > writeClipboard(x)
copies the string “hello world” to the clipboard as expected. However the code
> x <- 3.14 > writeClipboard(x)
produces the error message
Error in writeClipboard(str, format) : argument must be a character vector or a raw vector
The solution is to call
writeClipboard( as.character(x) ), casting the object
x to a character string.
All variables in R are vectors, and elements of a vector can have differing types. If one element of a vector is a character string, all elements will be cast to strings without the need for an explicit
as.character statement. After a vector has been copied to the clipboard, the elements of the vector will be separated by newlines when pasted into a document.
The companion function for
x <- readClipboard()
will assign the contents of the clipboard to the vector
x. Each line becomes an element of
x. The elements will be character strings, even if the clipboard contained a column of numbers before the
readClipboard command was executed. If you select a block of numbers from Excel, each row becomes a single string containing tabs where there were originally cell boundaries.
You can use the
scan function to copy a column of numbers from Excel to R. Copy the column from Excel, run
x <- scan(), type Ctrl-v to paste into R, and press enter to signal the end of input to
x will contain the numbers from Excel as numbers, not as quoted strings. Note that
scan only works with columns of numbers. R will produce an error message if the copied column contained a string. If there is an empty cell, only the numbers above the first empty cell will be copied into the R vector.
scan works with columns in Excel. If you copy a row of numbers from Excel and call
scan, the numbers will be concatenated into a single number in R. For example, if you copy horizontally adjacent cells containing 19 and 44 and run
x <- scan(), then
x will contain 1944. To copy a row from Excel, first transpose the row in Excel, then copy the result as a column.
scan() is not limited to Excel. It could be used to paste a column of numbers copied from other applications, such as Word or Notepad.
read.table and write.table
The functions above only work with columns of data; rows are combined into single entries. To move a block of cells from
write.table(x, "clipboard", sep="\t") will copy a table
x to the clipboard in such a way that it can be pasted into Excel preserving the table structure. By default, the row and column names will come along with the table contents. To leave the row names behind, add the argument
row.names=FALSE to the call to
write.table(x, "clipboard", sep="\t", row.names=FALSE)
col.names=FALSE if you do not want the row names to come over to Excel.
write.table(x, "clipboard", sep="\t", row.names=FALSE, col.names=FALSE)
See also: R for programmers