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Michael Friendly

2013-Dec-02 14:47 UTC

[R] generate multiple probability distributions

I want to generate a collection of probability distributions in a data 
frame, with
varying parameters.  There must be some simpler way than what I have below
(avoiding rbind and cbind), but I can't quite see it.

x <- seq(0,12)
bin.df <- as.data.frame(
     rbind( cbind(x, prob=dbinom(x,12,1/6), p=1/6),
            cbind(x, prob=dbinom(x,12,1/3), p=1/3),
            cbind(x, prob=dbinom(x,12,1/2), p=1/2),
            cbind(x, prob=dbinom(x,12,2/3), p=2/3)
           ))
bin.df$p <- factor(bin.df$p, labels=c("1/6", "1/3",
"1/2", "2/3"))
str(bin.df)

 > str(bin.df)
'data.frame':   52 obs. of  3 variables:
  $ x   : num  0 1 2 3 4 5 6 7 8 9 ...
  $ prob: num  0.1122 0.2692 0.2961 0.1974 0.0888 ...
  $ p   : Factor w/ 4 levels "1/6","1/3","1/2",..:
1 1 1 1 1 1 1 1 1 1 ...
 >

-- 
Michael Friendly     Email: friendly AT yorku DOT ca
Professor, Psychology Dept. & Chair, Quantitative Methods
York University      Voice: 416 736-2100 x66249 Fax: 416 736-5814
4700 Keele Street    Web:   http://www.datavis.ca
Toronto, ONT  M3J 1P3 CANADA

Duncan Murdoch

2013-Dec-02 15:12 UTC

head link

[R] generate multiple probability distributions

On 02/12/2013 9:47 AM, Michael Friendly wrote:> I want to generate a collection of probability distributions in a data
> frame, with
> varying parameters.  There must be some simpler way than what I have below
> (avoiding rbind and cbind), but I can't quite see it.
>
> x <- seq(0,12)
> bin.df <- as.data.frame(
>       rbind( cbind(x, prob=dbinom(x,12,1/6), p=1/6),
>              cbind(x, prob=dbinom(x,12,1/3), p=1/3),
>              cbind(x, prob=dbinom(x,12,1/2), p=1/2),
>              cbind(x, prob=dbinom(x,12,2/3), p=2/3)
>             ))
> bin.df$p <- factor(bin.df$p, labels=c("1/6", "1/3",
"1/2", "2/3"))
> str(bin.df)
>
>   > str(bin.df)
> 'data.frame':   52 obs. of  3 variables:
>    $ x   : num  0 1 2 3 4 5 6 7 8 9 ...
>    $ prob: num  0.1122 0.2692 0.2961 0.1974 0.0888 ...
>    $ p   : Factor w/ 4 levels
"1/6","1/3","1/2",..: 1 1 1 1 1 1 1 1 1 1 ...
>   >
>
dbinom can take vector inputs for the parameters, so this would be a bit 
simpler:

x <- seq(0,12)
x <- rep(x, 4)
p <- rep(c(1/6, 1/3, 1/2, 2/3), each=13)
bin.df <- data.frame(x, prob = dbinom(x, 12, p), p)

Duncan Murdoch

David Carlson

2013-Dec-02 15:41 UTC

head link

[R] generate multiple probability distributions

You can use recycling to simplify things:
> set.seed(42)
> x <- seq(0,12)
> bin.df <- as.data.frame(+     rbind( cbind(x, prob=dbinom(x,12,1/6), p=1/6),
+            cbind(x, prob=dbinom(x,12,1/3), p=1/3),
+            cbind(x, prob=dbinom(x,12,1/2), p=1/2),
+            cbind(x, prob=dbinom(x,12,2/3), p=2/3)
+      ))> bin.df$p <- factor(bin.df$p, labels=c("1/6", "1/3",
"1/2",
"2/3"))> str(bin.df)'data.frame':   52 obs. of  3 variables:
 $ x   : num  0 1 2 3 4 5 6 7 8 9 ...
 $ prob: num  0.1122 0.2692 0.2961 0.1974 0.0888 ...
 $ p   : Factor w/ 4 levels "1/6","1/3","1/2",..:
1 1 1 1 1 1 1
1 1 1 ...> 
> bin.df.2 <- data.frame( x, +     prob = c(dbinom(x,12,1/6), dbinom(x,12,1/3),
+            dbinom(x,12,1/2), dbinom(x,12,2/3)),
+     p = rep(c(1/6, 1/3, 1/2, 2/3), each=length(x))
+ )> bin.df.2$p <- factor(bin.df$p, labels=c("1/6",
"1/3", "1/2",
"2/3"))> str(bin.df.2)'data.frame':   52 obs. of  3 variables:
 $ x   : int  0 1 2 3 4 5 6 7 8 9 ...
 $ prob: num  0.1122 0.2692 0.2961 0.1974 0.0888 ...
 $ p   : Factor w/ 4 levels "1/6","1/3","1/2",..:
1 1 1 1 1 1 1
1 1 1 ...> all.equal(bin.df, bin.df.2)[1] TRUE

-------------------------------------
David L Carlson
Department of Anthropology
Texas A&M University
College Station, TX 77840-4352




-----Original Message-----
From: r-help-bounces at r-project.org
[mailto:r-help-bounces at r-project.org] On Behalf Of Michael
Friendly
Sent: Monday, December 2, 2013 8:48 AM
To: R-help
Subject: [R] generate multiple probability distributions

I want to generate a collection of probability distributions in
a data 
frame, with
varying parameters.  There must be some simpler way than what I
have below
(avoiding rbind and cbind), but I can't quite see it.

x <- seq(0,12)
bin.df <- as.data.frame(
     rbind( cbind(x, prob=dbinom(x,12,1/6), p=1/6),
            cbind(x, prob=dbinom(x,12,1/3), p=1/3),
            cbind(x, prob=dbinom(x,12,1/2), p=1/2),
            cbind(x, prob=dbinom(x,12,2/3), p=2/3)
           ))
bin.df$p <- factor(bin.df$p, labels=c("1/6", "1/3",
"1/2",
"2/3"))
str(bin.df)

 > str(bin.df)
'data.frame':   52 obs. of  3 variables:
  $ x   : num  0 1 2 3 4 5 6 7 8 9 ...
  $ prob: num  0.1122 0.2692 0.2961 0.1974 0.0888 ...
  $ p   : Factor w/ 4 levels "1/6","1/3","1/2",..:
1 1 1 1 1 1 1
1 1 1 ...
 >

-- 
Michael Friendly     Email: friendly AT yorku DOT ca
Professor, Psychology Dept. & Chair, Quantitative Methods
York University      Voice: 416 736-2100 x66249 Fax: 416
736-5814
4700 Keele Street    Web:   http://www.datavis.ca
Toronto, ONT  M3J 1P3 CANADA

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R help - Dec 2013 - generate multiple probability distributions

[R] generate multiple probability distributions

[R] generate multiple probability distributions

[R] generate multiple probability distributions