R package oce: binAverage

library(oce)

X11()

x <- c(  13.1 , 16.2 , 12.9    ,   28.7 , 25.4   ,   31.5 , 36.5 , 33.3  ,
         11.8 , 17.6           ,   26.4 , 21.3   ,   38.3 , 37.4 , 31.5   )

y <- c(    1  ,    3 ,    6    ,      5 ,    9   ,     12 ,   10 ,   11  ,
           5  ,    8           ,     11 ,    7   ,      9 ,    8 ,    9   )

stopifnot(length(x) == length(y))

plot(x=x, y=y, bg='red', col='orange', pch=21)


avg <- binAverage(x, y, xmin=10, xmax=40, xinc=10)

lines( c(10, 20), c(avg$y[1], avg$y[1]), col='blue')
lines( c(20, 30), c(avg$y[2], avg$y[2]), col='blue')
lines( c(30, 40), c(avg$y[3], avg$y[3]), col='blue')

# Wait for mouse click
invisible(locator(1))

sum(y[x<20]) / length(y[x<20])
# [1] 4.6
avg$y[1]
# [1] 4.6

sum(y[x>20 & x<30]) / length(y[x>20 & x<30])
# [1] 8
avg$y[2]
# [1] 8

sum(y[x>30 & x<40]) / length(y[x>30 & x<40])
# [1] 9.833333
avg$y[3]
# [1] 9.833333

The plot produces: