R-基于其他列和行的绝对差的累积和

Question

My data has the following format:

• first column: indication if the machine is running
• second column: Coordinate to indicate the distance that the machine is running

See here below the dataset:

structure(c("", "", "running", "running", "running", "running", 
"running", "running", "running", "", "504", "678", "268", "475", 
"675", "796", "745", "693", "665", "488"), .Dim = c(10L, 2L), .Dimnames = list(
    NULL, c("e", "f")))

I would like to add a third column that gives the total distance that the machine has been running (by adding all the absolute differences since the machine started to run). See here below the desired output:

   e         f     Output
 [1,] ""        "504" ""    
 [2,] ""        "678" ""    
 [3,] "running" "268" "0"   
 [4,] "running" "475" "207" 
 [5,] "running" "675" "407" 
 [6,] "running" "796" "528" 
 [7,] "running" "745" "579" 
 [8,] "running" "693" "631" 
 [9,] "running" "665" "659" 
[10,] ""        "488" "" 

I tried to write some code in R to get this in an elegant way, but my programming skills are too limited for the moment. Is there anybody that knows a solution for this problem? Thank you on beforehand!

Answer 1

Actually I have to confess I did not fully understand your question...

Do you mean something like this?

a <- c("", "", "running", "running", "running", "running", 
  "running", "running", "running", "", "504", "678", "268", "475", 
  "675", "796", "745", "693", "665", "488")

a <- data.frame(matrix(a, ncol=2), stringsAsFactors=FALSE)
a[,2] <- as.numeric(a[,2])

subs.a <- subset(a, X1=='running')
abs(diff(subs.a$X2))
cumsum(diff(subs.a$X2))

this returns

  abs(diff(subs.a$X2)) 
  [1] 207 200 121  51  52  28
  cumsum(abs(diff(subs.a$X2)))
  [1] 207 407 528 579 631 659

inserting it into the data.frame :

a[a$X1=='running', 'CumSum'] <- c(0,cumsum(abs(diff(subs.a$X2))))

Answer 2

This gives you the desired data frame:

df <- data.frame(structure(c("", "", "running", "running",     "running",     "running", 
        "running", "running", "running", "", "504", "678", "268", "475", 
        "675", "796", "745", "693", "665", "488"), .Dim = c(10L, 2L), .Dimnames = list(
          NULL, c("e", "f"))), stringsAsFactors = F)

runs <- df$e == "running"

df$f <- as.numeric(df$f)
diff <- abs(diff(df$f[runs]))
df$Output[runs] <- 0
df$Output[runs][-1] <- cumsum(diff)

You get:

         e   f Output
1          504     NA
2          678     NA
3  running 268      0
4  running 475    207
5  running 675    407
6  running 796    528
7  running 745    579
8  running 693    631
9  running 665    659
10         488     NA