F Duan wrote:
Dear All,
I have a data frame with n columns: X1, X2, ., Xn. Now I want to create a
new column: if X1 = X2 = . = Xn, the value is 1; Otherwise, the value is 0.
How to do that in a quick way instead of doing (n choose 2) comparisons?
Thank you,
Frank
How about something like?
x <- data.frame(X1 = c(1, 1, 2, 4),
X2 = c(4, 1, 2, 5),
X3 = c(2, 1, 2, 2))
nuniq <- function(x) length(unique(x))
as.numeric(apply(as.matrix(x), 1, nuniq) == 1)
--sundar
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