[R] CORRECTION - Generation of Random numbers in a loop

[Gray Calhoun]

Hi Maithili,
  This is probably easiest if you think in terms of functions.  Just
apply 'runif' along the right vectors

## gives you one data frame with the min and max
limits <- read.table(textConnection("name min max
A11    1.05  1.30
A12    1.30  1.60
A13    1.60  1.99"), header = TRUE)
d <- merge(ONS, limits)

cbind(randomdraw = unlist(mapply(runif, d$number, d$min, d$max)), name
= rep(d$name, d$number))

## now save it to a csv file, etc.


On Wed, Dec 16, 2009 at 10:35 PM, Maithili Shiva
<maithili_shiva at yahoo.com> wrote:
> Dear R helpers, please ignore my earlier mail. Here is the corrected mail. Please forgive me for the lapses on my part. Extremely sorry.
>
> Here is the corrected mail.
>
>
> Dear R helpers
>
> I am having following data
>
> Name           Numbers
> A11                  12
> A12                  17
> A13                   0
> A11                  11
> A12                   6
> A13                   0
> A11                   8
> A12                   4
> A13                   3
>
> CONDITIONS
>
> If Name is A11, min_val = 1.05, max_val = 1.30
> If Name is A12, min_val = 1.30, max_val = 1.60
> If Name is A13, min_val = 1.60, max_val = 1.99
>
> TASK
>
> To generate the Uniform random nos for each of these Names (Equal to the corresponding no. e.g. the 5th Name is A12, so I need to generate 6 uniform random numbers in the range (1.30 - 1.99). Also I need to arrange these random numbers one by one in a single csv file i.e. say 12 random numbers in teh range (1.05-1.30) followed by 17 random numbers in the range (1.30-1.60) and so on.
>
> # ___________________________________________________
>
> Here is the R code I have tried
>
> ONS <- read.table(textConnection("name number
> A11    12
> A12    17
> A13     0
> A11    11
> A12      6
> A13      0
> A11      8
> A12      4
> A13      3"), header = TRUE)
>
> X = as.character(ONS$name)
> Y = ONS$number
>
> Z = NULL
>
> for (i in 1:length(X))
>    {
>    if(X[i] == 'A11')
>    {
>    min_val = 1.05
>    max_val = 1.30
>    Z = runif(Y[i], min_val, max_val)
>    }
>    else
>    {
>    if(X[i] == 'A12')
>    {
>    min_val = 1.30
>    max_val = 1.60
>    Z = runif(Y[i], min_val, max_val)
>    }
>    else
>    {
>    if(X[i] == 'A13')
>    {
>    min_val = 1.60
>    max_val = 1.99
>    Z = runif(Y[i], min_val, max_val)
>    }
>    }
>    }
>    }
>
> # End of Code
>
> ## _____________________________________________________________________
>
> PROBLEM
>
> I need to get 61 random numbers which is total of all the numbers (1st 12 fo A, 3 random numbers for B, 13 for C, 5 again fo A and so on). The result whcih I got is
>
>> Z
> [1] 1.740443 1.761758 1.797222
>
> which is pertaining to the last name C where 3 random numbers are generated i.e. Z instaed of getting added, is overwritten.
>
> Please help me to rectify my code so that in the end I will get 61 random numbers as desired i.e. 12 for A in the range (1.05 - 1.30), 3 for B in the range (1.30 - 1.60), 13 for C in the range (1.60-1.99), again 5 for A in the range (1.05 - 1.30).
>
> Thanking in advance. I also sincerely apologize for writing such a long mail, as I wanted to be clear as possible in my communication.
>
> Regards
>
> Maithili
>
>
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>
>
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>
>



-- 
Gray Calhoun

Assistant Professor of Economics
Iowa State University