store for loop values in variable in R

Question

I am using a for loop obtain a set of p-values using the "pbinom" function. The values 1:5 simply refer to the number of observed counts, 21, refers to the sample size, and 0.05 refers to the probability of success:

for ( i in 1:5) {
print (1 - pbinom(i, 21, 0.05))
}

[1] 0.2830282
[1] 0.08491751
[1] 0.01888063
[1] 0.00324032
[1] 0.0004415266

This code works fine, but it just outputs the values the values on the command prompt as above.

My question is, how can I store the output in a variable?

I tried

output<-for ( i in 1:5) {
print (1 - pbinom(i, 21, 0.05))
}

But when I entered "output", I received "NULL" in response.

Any help would be appreciated, Thanks.

David Arenburg · Accepted Answer · 2015-03-04 21:08:07Z

4

Don't use a for loop at all for this. pbinom is vectorized. Just do

(output <- 1 - pbinom(1:5, 21, 0.05))
## [1] 0.2830281552 0.0849175139 0.0188806334 0.0032403196 0.0004415266

In a worst case scenario you can use sapply instead which outputs the vector by default, something like

(output <- 1 - sapply(1:5, pbinom, 21, 0.05))
## [1] 0.2830281552 0.0849175139 0.0188806334 0.0032403196 0.0004415266

answered Mar 4, 2015 at 21:08

David Arenburg

92.4k18 gold badges145 silver badges202 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Rish Over a year ago

Thanks for your answer, David. I just have one follow up question: If had multiple probabilities of success, say 0.05 and 0.02. How can I get the same output in your answer, but with a vector of p-values for each success probability (separated by row), such that row one represents the pvalues for 0.05 and row two represents the pvalues from 0.02?

David Arenburg Over a year ago

1 - pbinom(1:2, 21, c(0.02, 0.05))?

Rish Over a year ago

I tried this, but only outputs the pvalues for the first value in the vector, so all pvalues for 0.02

David Arenburg Over a year ago

Nope. Compare to 1 - pbinom(1:2, 21, 0.05) and 1 - pbinom(1:2, 21, 0.02) and then find the difference.

Rish Over a year ago

So after entering all the above commands, I see that 1 - pbinom(1:2, 21, c(0.02, 0.05)), I get [1] 0.06534884 0.08491751, which corresponds to the outputs obtained by: 1 - pbinom(1, 21, 0.02) and 1 - pbinom(2, 21, 0.05), respectively. My desired output would be: [1] 0.065348840 0.008125299 (row 1) and [1] 0.28302816 0.08491751 (row 2). Perhaps you got this output? I'm not sure what I'm doing incorrectly. Thanks again.

|

jimh · Accepted Answer · 2015-03-04 21:05:41Z

1

You can't pass a for loop into a variable like that. You could try this:

output=c()
for (i in 1:5){
output[i]=(1-pbinom(i,21,0.05))
}

Then if you type:

output

R will produce:

[1] 0.2830281552 0.0849175139 0.0188806334 0.0032403196 0.0004415266

answered Mar 4, 2015 at 21:05

jimh

1,9762 gold badges18 silver badges30 bronze badges

Collectives™ on Stack Overflow

store for loop values in variable in R

2 Answers 2

6 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

6 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related