This should be very simple, but my r knowledge is limited. I'm trying to find out if any value is greater than all previous values. An example would be
x<-c(1.1, 2.5, 2.4, 3.6, 3.2)
results:
NA True False True False
My real values are measurements with many decimal places so I doubt I will get the same value twice
You can use cummax()
to get the biggest value so far. x >= cummax(x)
basically gives you the answer, although element 1 is TRUE
, so you just need to change that:
> out = x >= cummax(x)
> out[1] = NA
> out
[1] NA TRUE FALSE TRUE FALSE
Although @Marius has got this absolutely correct. Here is an option with a loop
sapply(seq_along(x), function(i) all(x[i] >= x[seq_len(i)]))
#[1] TRUE TRUE FALSE TRUE FALSE
Or same logic with explicit for
loop
out <- logical(length(x))
for(i in seq_along(x)) {
out[i] <- all(x[i] >= x[seq_len(i)])
}
out[1] <- NA
out
#[1] NA TRUE FALSE TRUE FALSE
We can use lapply
unlist(lapply(seq_along(x), function(i) all(x[i] >=x[seq(i)])))
#[1] TRUE TRUE FALSE TRUE FALSE
Or with max.col
max.col(t(sapply(x, `>=`, x)), 'last') > seq_along(x)
#[1] FALSE TRUE FALSE TRUE FALSE
or with for
loop
mx <- x[1]
i1 <- logical(length(x))
for(i in seq_along(x)) {i1[i][x[i] > mx] <- TRUE; mx <- max(c(mx, x[i]))}
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