[R] for loop is looping only once

[Ulrik Stervbo]

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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