[R] Generating input population for microsimulation

[Jan van der Laan]

Emma,

If, as you say, each unit is the same you can just repeat the units to  
obtain the required number of units. For example,


   unit_size <- 10
   n_units <- 10

   unit_id <- rep(1:n_units, each=unit_size)
   pid     <- rep(1:unit_size, n_units)
   senior  <- ifelse(pid <= 2, 1, 0)

   pop <- data.frame(unit_id, pid, senior)


If you want more flexibility in generating the units, I would first  
generate the units (without the persons) and then generate the persons  
for each unit. In the example below I use the plyr package; you could  
probably also use lapply/sapply, or simply a loop over the units.

   library(plyr)

   generate_unit <- function(unit) {
       pid <- 1:unit$size
       senior <- rep(0, unit$size)
       senior[sample(unit$size, 2)] <- 1
       return(data.frame(unit_id=unit$id, pid=pid, senior=senior))
   }

   units <- data.frame(id=1:n_units, size=unit_size)

   library(plyr)
   ddply(units, .(id), generate_unit)


HTH,

Jan




Emma Thomas <thomas_ek at yahoo.com> schreef:

> Hi all,
>
> I've been struggling with some code and was wondering if you all could help.
>
> I am trying to generate a theoretical population of P people who are  
> housed within X different units. Each unit follows the same  
> structure- 10 people per unit, 8 of whom are junior and two of whom  
> are senior. I'd like to create a unit ID and a unique identifier for  
> each person (person ID, PID) in the population so that I have a  
> matrix that looks like:
>
>      unit_id pid senior
>   [1,]      1   1      0
>   [2,]      1   2      0
>   [3,]      1   3      0
>   [4,]      1   4      0
>   [5,]      1   5      0
>   [6,]      1   6      0
>   [7,]      1   7      0
>   [8,]      1   8      0
>   [9,]      1   9      1
>   [10,]    1   10   1
> ...
>
> I came up with the following code, but am having some trouble  
> getting it to populate my matrix the way I'd like.
>
> world <- function(units, pop_size, unit_size){
>     pid <- rep(0,pop_size) #person ID
>     senior <- rep(0,pop_size) #senior in charge
>     unit_id <- rep(0,pop_size) #unit ID
>    
>         for (i in 1:pop_size){
>         for (f in 1:units)    { 
>         senior[i] = sample(c(1,1,0,0,0,0,0,0,0,0), 1, replace = FALSE)
>         pid[i] = sample(c(1:10), 1, replace = FALSE)
>         unit_id[i] <- f
>                 }}   
>     data <- cbind(unit_id, pid, senior)
>    
>     return(data)
>     }
>
>     world(units = 10,pop_size = 100, unit_size = 10) #call the function
>
>
>
> The output looks like:
>      unit_id pid senior
>   [1,]      10   7      0
>   [2,]      10   4      0
>   [3,]      10  10      0
>   [4,]      10   9      1
>   [5,]      10  10      0
>   [6,]      10   1      1
> ...
>
> but what I really want is to generate is 10 different units with two  
> seniors per unit, and with each person in the population having a  
> unique identifier.
>
> I thought a nested for loop was one way to go about creating my data  
> set of people and families, but obviously I'm doing something (or  
> many things) wrong. Any suggestions on how to fix this? I had been  
> focusing on creating a person and assigning them to a unit, but  
> perhaps I should create the units and then populate the units with  
> people?
>
> Thanks so much in advance.
>
> Emma
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.