using if else function to complete a column in data frame

Hi

Split option seems to me the most effective and ifelse is in this case not necessary.

You can use this function to estimate levels

fff <- function(x) sign(diff(x))
test.s <- split(test, test$ID)
for (i in 1:length(test.s)) test.s[[i]]$movimento[-1] <- fff(test.s[[i]][,2])
test <- do.call(rbind, test.s)
test[,3] <- factor(test[,3], levels=c(-1, 0, 1), labels=c("jusante", "parado", "montante"))
test

To avoid extension of row names you can use
library (plyr)
test<-ldply (test.s, data.frame)

instead of do.call.

I tried assigning factor within for cycle

fff<- function(x) factor(sign(diff(x)), levels=c(-1, 0, 1), labels=c("jusante", "parado", "montante"))
test.s <- split(test, test$ID)
for (i in 1:length(test.s)) test.s[[i]]$movimento[-1] <- fff(test.s[[i]][,2])
test <- do.call(rbind, test.s)
test

but assigned in this case is not factor but numeric vector, which seems to me strange. Maybe somebody could explain this behaviour

Cheers
Petr

-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Cacique
Samurai
Sent: Monday, January 9, 2017 6:22 AM
To: R help <r-help at r-project.org>
Subject: [R] using if else function to complete a column in data frame

Hello all!

I?m trying to complete the "movimento" column in dataframe based in the
values of "kmr" column in two sequential lines, as below:

data example (dput in the end of email):

         ID    kmr movimento
5    10.700 314.20        NA
1    10.700 278.74        NA
2    10.700 278.74        NA
3    10.700 278.74        NA
4    10.700 278.74        NA
494 100.700 269.94        NA
500 100.700 278.74        NA
499 100.700 314.20        NA
495 100.700 278.74        NA
498 100.700 278.74        NA
496 100.700 255.40        NA
497 100.700 255.10        NA

Once I have different IDs, I wrote this function:

move = function (x){

  for (j in x$ID){

    for (i in 2:length(x$kmr)-1){

      if (x$kmr[i+1]  < x$kmr[i]) {
        x$movimento[i+1] <- "jusante"
      } else if (x$kmr[i+1] > x$kmr[i]) {
        x$movimento[i+1] <- "montante"
      } else {
        x$movimento[i+1] <- "parado"
      }

    }

  }

  return (x)
}

Worked pretty well with just one ID, but with many IDs the function didn?t
detach different IDs.

         ID    kmr movimento
5    10.700 314.20      <NA>
1    10.700 278.74   jusante
2    10.700 278.74    parado
3    10.700 278.74    parado
4    10.700 278.74    parado
494 100.700 269.94   jusante <-- this should be <NA>
500 100.700 278.74  montante
499 100.700 314.20  montante
495 100.700 278.74   jusante
498 100.700 278.74    parado
496 100.700 255.40   jusante
497 100.700 255.10   jusante

I also tried remove the first If condition and pass this function using lapply in
the splitted original data-frame, but didn?t work as well.

Some onde can help?

Thanks in advanced,

Raoni

structure(list(ID = c("10.700", "10.700", "10.700", "10.700", "10.700",
"100.700", "100.700", "100.700", "100.700", "100.700", "100.700", "100.700"),
kmr = c(314.2, 278.74, 278.74, 278.74, 278.74, 269.94, 278.74, 314.2, 278.74,
278.74, 255.4, 255.1),
    movimento = c(NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
    NA)), .Names = c("ID", "kmr", "movimento"), row.names = c(5L, 1L, 2L, 3L,
4L, 494L, 500L, 499L, 495L, 498L, 496L, 497L), class = "data.frame")

--
Raoni Rosa Rodrigues
Research Associate of Fish Transposition Center CTPeixes Universidade
Federal de Minas Gerais - UFMG Brasil rodrigues.raoni at gmail.com

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