Pipe processing

Note:

• This R-package is still in development, and therefore some of the functions may change in a near future.
• If you have any questions, comments or suggestions, feel free to contact me (in english, french or german): emanuel.huber@pm.me.

Table of Contents

• Objectives of this tutorial
• Preliminary
  • Install/load RGPR
  • The GPR data
  • Compute time zero
• Using the pipe operators with RPGR
  • Basic piping
  • The |> pipe operator

Objectives of this tutorial

• Learn how to use the pipe operator %>% to process elegantly GPR data.

Preliminary

• Read the tutorial Basic GPR data processing to learn more about the processing methods

Install/load RGPR

# install "remotes" if not already done
if(!require("remotes")) install.packages("remotes")
remotes::install_github("emanuelhuber/RGPR")
library(RGPR)       # load RGPR in the current R session

The GPR data

RPGR comes along with a GPR data called frenkeLine00. Because this name is long, we set x equal to frenkeLine00:

x <- frenkeLine00
plot(x)

Compute time zero

tfb <- firstBreak(x, w = 10, method = "coppens", thr = 0.05)
plot(x[,1], relTime0 = FALSE, xlim = c(0, 100))
t0 <- firstBreakToTime0(tfb[1], x[,1])
abline(v = c(tfb[1], t0[1]), col = c("green", "blue"))

Using the pipe operators with RPGR

Basic piping

Here a short excerpt that explains how to use pipe operators:

https://rstudio-pubs-static.s3.amazonaws.com/1368525_31210c1c422f4faa9c8df4364ea8543d.html

Note: In the following, we will only focus on the base R pipe operator |>.

The operators pipe their left-hand side values forward into expressions that appear on the right-hand side, i.e. one can replace f(x) with x |> f(), where |> is the pipe operator.

• x |> f is equivalent to f(x)
• x |> f(y) is equivalent to f(x, y)
• x |> f |> g |> h is equivalent to h(g(f(x)))

With pipe operators, the code is more compact and better readable.

The |> pipe operator

Without pipe operator, we would code something like that:

time0(x) <- t0
x1 <- dcshift(x)
x2 <- dewow(x1, type = "runmed", w = 50)
x3 <- time0Cor(x2)
x4 <- fFilter(x3, f = c(100, 280), type = "low", plotSpec = FALSE)
x5 <- gain(x4, type = "agc", w =  5)

The same code with the |> pipe operator.

xnew <- x |> 
  setTime0(t0) |>
  dcshift() |>
  dewow(type = "runmed", w = 50) |>
  time0Cor() |>
  fFilter(f = c(100, 280), type = "low", plotSpec = FALSE)  |>
  gain(type = "agc", w =  5)

Note that we here the setTime0() instead of time0()<-. setTime0() is nothing else than a wrapper for time0()<-:

setTime0 <- function(x, t0){
  time0(x) <- t0
}

Currently, the other replace methods of RGPR(function()<-) do not have such a wrapper. Don’t hesitate to write you own wrapper.