R, graph of binomial distribution

Question

I have to write own function to draw the density function of binomial distribution and hence draw appropriate graph when n = 20 and p = 0.1,0.2,...,0.9. Also i need to comments on the graphs. I tried this ; ``` graph <- function(n,p){ x <- dbinom(0:n,size=n,prob=p) return(barplot(x,names.arg=0:n)) } graph(20,0.1) graph(20,0.2) graph(20,0.3) graph(20,0.4) graph(20,0.5) graph(20,0.6) graph(20,0.7) graph(20,0.8) graph(20,0.9) #OR graph(20,scan()) ``` My first question : is there any way so that i don't need to write down the line `graph(20,p)` several times except using `scan()`? My second question : I want to see the graph in one device or want to hit `ENTER` to see the next graph. I wrote ``` par(mfcol=c(2,5)) graph(20,0.1) graph(20,0.2) graph(20,0.3) graph(20,0.4) graph(20,0.5) graph(20,0.6) graph(20,0.7) graph(20,0.8) graph(20,0.9) ``` but the graph is too tiny. How can i present the graphs nicely with giving head line n=20 and p=the value which i used to draw the graph?[though it ca…

Accepted Answer

Here a job of `mapply` since you loop over 2 variables.

```
graph <- function(n,p){
  x <- dbinom(0:n,size=n,prob=p)
  barplot(x,names.arg=0:n,
         main=sprintf(paste('bin. dist. ',n,p,sep=':')))
}
par(mfcol=c(2,5))
  mapply(graph,20,seq(0.1,1,0.1))
```

R, graph of binomial distribution

Solution

Problem