how to calculate Riemann Sums in R?
curve, r
Solution
Check this demo :
> library(zoo)
> x <- 1:10
> y <- -x^2
> Result <- sum(diff(x[x]) * rollmean(y[x], 2))
> Result
[1] -334.5
After check this question, I found function `trapz()` from package `pracma` be more efficient:
> library(pracma)
> Result.2 <- trapz(x, y)
> Result.2
[1] -334.5
Problem
Can any one help how to find approximate area under the curve using Riemann Sums in R? It seems we do not have any package in R which could help. Sample data: ``` MNo1 X1 Y1 MNo2 X2 Y2 1 2981 -66287 1 595 -47797 1 2981 -66287 1 595 -47797 2 2973 -66087 2 541 -47597 2 2973 -66087 2 541 -47597 3 2963 -65887 3 485 -47397 3 2963 -65887 3 485 -47397 4 2952 -65687 4 430 -47197 4 2952 -65687 4 430 -47197 5 2942 -65486 5 375 -46998 5 2942 -65486 5 375 -46998 6 2935 -65286 6 322 -46798 6 2935 -65286 6 322 -46798 7 2932 -65086 7 270 -46598 7 2932 -65086 7 270 -46598 8 2936 -64886 8 222 -46398 8 2936 -64886 8 222 -46398 9 2948 -64685 9 176 -46198 9 2948 -64685 9 176 -46198 10 2968 -64485 10 135 -45999 10 2968 -64485 10 135 -45999 11 2998 -64284 11 97 -45799 11 2998 -64284 11 97 -45799 12 3035 -64084 12 65 -45599 12 3035 -64084 12 65 -45599 13 3077 -63883 13 37 -45399 13 3077 -63883 13 37 -45399 14 3122 -63683 14 14 -45199 14 3122 -63683 14 14 -45199 15 3168 -63482 15 -5 -44999 15 3168 -63482 15 -5 -44999 16 3212 -63282 16 -20 -44799 16 3212 -63282 16 -20 -44799 17 3250 -63081 17 -31 -44599 17 3250 -63081 17 -31 -44599 18 3280 -62881 18 -38 -44399 18 3280 -62881 18 -38 -44399 19 3301 -62680 19 -43 -44199 19 3301 -62680 19 -43 -44199 20 3313 -62480 20 -45 -43999 ```