peakypeaks

library(pracma)
library(data.table)

t <- seq(0, 10, 0.1)

dt_x <- data.table(id = "x", time = t, values = sin(t))
dt_y <- data.table(id = "y", time = t, values = cos(t))

dt <- rbind(dt_x, dt_y)

peaks_x <- findpeaks(dt[id == "x", values])
peaks_y <- findpeaks(dt[id == "y", values])