R help - Oct 2010 - Generate random percentages and placing vectors

Hello everyone,

I have two questions:

1.) I would like to generate random percentages that add up to 100. For
example, if I need 5 percentages, I would obtain something like: 20, 30, 40,
5, 5. Is there some way to do this in R?

2.) I would like to insert vectors of specified length into a larger vector
of specified length randomly, and fill the gaps with zeroes. For example, if
I have 3 vectors of length 3, 2, and 2 with values and I would like to
randomly place them into a vector of length 25 made of 0's.

Thank you in advance!

-Aaron

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On Oct 27, 2010, at 11:02 AM, Aaron Lee wrote:
> Hello everyone,
>
> I have two questions:
>
> 1.) I would like to generate random percentages that add up to 100.  
> For
> example, if I need 5 percentages, I would obtain something like: 20,  
> 30, 40,
> 5, 5. Is there some way to do this in R?
>
> 2.) I would like to insert vectors of specified length into a larger  
> vector
> of specified length randomly, and fill the gaps with zeroes. For  
> example, if
> I have 3 vectors of length 3, 2, and 2 with values and I would like to
> randomly place them into a vector of length 25 made of 0's.
You need to specify the order of placement and whether over-writing is  
allowed. If overwriting is not allowed then after the first is placed  
the allowable positions may shrink in odd ways.
>
> Thank you in advance!
>

David Winsemius, MD
West Hartford, CT

1)
rands <- runif(5)
rands <- rands/sum(rands)*100

2)
# assume vectors are v1, v2, etc.
v_all <- c(v1, v2, ...)
v_len <- length(v_all)

output <- rep(0,25)
output[sample(1:25, v_len)] <- v_all

--------------------------------------
Jonathan P. Daily
Technician - USGS Leetown Science Center
11649 Leetown Road
Kearneysville WV, 25430
(304) 724-4480
"Is the room still a room when its empty? Does the room,
 the thing itself have purpose? Or do we, what's the word... imbue it."
     - Jubal Early, Firefly



From:
Aaron Lee <aaron.zl.lee@gmail.com>
To:
r-help@r-project.org
Date:
10/27/2010 11:06 AM
Subject:
[R] Generate random percentages and placing vectors
Sent by:
r-help-bounces@r-project.org



Hello everyone,

I have two questions:

1.) I would like to generate random percentages that add up to 100. For
example, if I need 5 percentages, I would obtain something like: 20, 30, 
40,
5, 5. Is there some way to do this in R?

2.) I would like to insert vectors of specified length into a larger 
vector
of specified length randomly, and fill the gaps with zeroes. For example, 
if
I have 3 vectors of length 3, 2, and 2 with values and I would like to
randomly place them into a vector of length 25 made of 0's.

Thank you in advance!

-Aaron

                 [[alternative HTML version deleted]]

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