[R] Antwort: Re: for loop is looping only once [SOLVED]

[G.Maubach at weinwolf.de]

Hi Ulrik,

oh no! What a mistake did I make. But I definitely did not see the 
failure.

Many thanks for helping me.

Kind regards

Georg




Von:    Ulrik Stervbo <ulrik.stervbo at gmail.com>
An:     G.Maubach at weinwolf.de, r-help at r-project.org, 
Datum:  17.11.2016 12:24
Betreff:        Re: [R] for loop is looping only once



Hi Georg,

Your for loop iterates over just one value, to get it to work as you 
intend use for(item in 1:length(kpis)){}

HTH
Ulrik

On Thu, 17 Nov 2016 at 12:18 <G.Maubach at weinwolf.de> wrote:
Hi All,

I need to execute a loop on variables to compute several KPIs.
Unfortunately the for loop is executed only once for the last KPI given.
The code below illustrates my current solution but is not completely
necessary to spot the problem. I just give an idea what I am doing
overall. Looks much but isn't if copied and run in RStudio. The problem
occurs in function f_create_kpi_table() in lines 150 to 157:

  for (item in length(kpis))  # This loop runs only once!
  {
    print(kpis[[item]])
    ds_kpi <- f_compute_kpi(
      years    = years,
      kpi      = kpis[[item]],
      kpi_base = kpi_bases[[item]])
    print(ds_kpi)

Here is the complete example code with example data:

- cut --
dataset <-
  structure(
    list(
      to_2012 = c(
        85,
        822,
        891,
        700,
        386,
        127,
        938,
        381,
        871,
        254,
        793,
        0,
        934,
        217,
        163,
        755,
        607,
        794,
        477
      ),
      to_2013 = c(
        289,
        0,
        963,
        243,
        608,
        47,
        0,
        941,
        998,
        775,
        326,
        0,
        0,
        470,
        248,
        439,
        212,
        0,
        0
      ),
      to_2014 = c(0, 0, 71, 0, 0, 434, 0, 282, 0,
                  0, 405, 0, 0, 642, 0, 0, 0, 47, 299),
      to_2015 = c(
        705,
        134,
        659,
        0,
        609,
        807,
        783,
        0,
        0,
        304,
        141,
        500,
        0,
        0,
        764,
        790,
        851,
        0,
        802
      ),
      kpi1_2013 = c(0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0,
                    0, 0, 0, 1, 1),
      kpi1_2014 = c(1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0,
                    1, 1, 0, 1, 1, 1, 0, 0),
      kpi1_2015 = c(0, 0, 0, 1, 0, 0, 0, 1,
                    1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0),
      kpi1_2016 = c(0, 1, 0, 1, 0,
                    1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 0, 0, 0, 1),
      kpi2_2013 = c(1, 0,
                    1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0),
      kpi2_2014 = c(0,
                    0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 1),
      kpi2_2015 = c(1,
                    1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 1, 0, 0, 1, 1, 1, 0, 1),
      kpi2_2016 = c(1,
                    0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0)
    ),
    .Names = c(
      "to_2012",
      "to_2013",
      "to_2014",
      "to_2015",
      "kpi1_2013",
      "kpi1_2014",
      "kpi1_2015",
      "kpi1_2016",
      "kpi2_2013",
      "kpi2_2014",
      "kpi2_2015",
      "kpi2_2016"
    ),
    row.names = c(NA, 19L),
    class = "data.frame"
  )

f_compute_kpi <- function(
  years,
  kpi,
  kpi_base)
{
  print(years)
  print(kpi)
  print(kpi_base)

  ds_result <- data.frame()

  for (year in years) {
    current_year  <- year
    previous_year <- year - 1
    result <- sum(dataset[dataset[[paste0(kpi,
                                          "_",
                                          current_year)]] == 1 ,
                          paste0(kpi_base,
                                 "_", previous_year)],
                  na.rm = TRUE)
    ds_result <- rbind(ds_result, result)
  }

  ds_result           <- t(ds_result)
  rownames(ds_result) <- kpi
  colnames(ds_result) <- years

  invisible(ds_result)
}

f_create_kpi_table <- function(
  years,
  kpis,
  kpi_bases)
{
  print(length(kpis))

#-- Problematic loop --
  for (item in length(kpis))  # This loop runs only once!
  {
    print(kpis[[item]])
    ds_kpi <- f_compute_kpi(
      years    = years,
      kpi      = kpis[[item]],
      kpi_base = kpi_bases[[item]])
    print(ds_kpi)
  }
  # This for loop is executed only once for kpi2 instead of
  # as many times as given kpis in length(kpis), i. e.
  # kpi1 AND kpi2.
  # Why?
  # What do I do wrong?
}
-- cut --

What do I need to change to get the loop work correctly and loop over two
elements instead of one when calling the function

f_create_kpi_table(years = 2013:2016, kpis = c("kpi1", "kpi2"), kpi_bases
= c("to", "to"))

Kind regards

Georg

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