R help - Nov 2009 - Basic question on nominal data

Hello everybody,

I am new to R and I have a very basic question, but I couldn't get
this to work.
Let's say I have a vector

s =
c("a","a","a","b","b","c","c","c","c")
s1 <- factor(s)

s2 <- summary(s1) leads to the following
a b c
3 2 4


How can I access the different aggregated values for a b and c? I am
not quite sure if the factor method is the right approach.
I tried to use s2$a but it didn't work.

Any suggestions?

Thanks a lot for your help

Marc

Hi,
 
try ?table
 
# for example
 
(s3 <- table(s))
 
# and if you want a single value
 
s3["a"]
# or
s3[1]
 
HTH,
Colin.
 
 

________________________________

From: r-help-bounces@r-project.org on behalf of Marc Giombetti
Sent: Tue 17/11/2009 22:55
To: r-help@r-project.org
Subject: [R] Basic question on nominal data



Hello everybody,

I am new to R and I have a very basic question, but I couldn't get
this to work.
Let's say I have a vector

s =
c("a","a","a","b","b","c","c","c","c")
s1 <- factor(s)

s2 <- summary(s1) leads to the following
a b c
3 2 4


How can I access the different aggregated values for a b and c? I am
not quite sure if the factor method is the right approach.
I tried to use s2$a but it didn't work.

Any suggestions?

Thanks a lot for your help

Marc

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	[[alternative HTML version deleted]]

On 17-Nov-09 22:55:32, Marc Giombetti wrote:
> Hello everybody,
> I am new to R and I have a very basic question, but I couldn't get
> this to work.
> Let's say I have a vector
> 
> s =
c("a","a","a","b","b","c","c","c","c")
> s1 <- factor(s)
> 
> s2 <- summary(s1) leads to the following
> a b c
> 3 2 4
> 
> How can I access the different aggregated values for a b and c? I am
> not quite sure if the factor method is the right approach.
> I tried to use s2$a but it didn't work.
> 
> Any suggestions?
> 
> Thanks a lot for your help
> Marc
s2$a doesn't work because s2 is not a list. It is a vector.
You can find this out with

  str(s2)
  # Named int [1:3] 3 2 4
  # - attr(*, "names")= chr [1:3] "a" "b"
"c"

so you can access its elements in the usual way; also by exploiting
its "names" attribute:

  s2[1]
  # a 
  # 3 
  s2["a"]
  # a 
  # 3 
  s2[2]
  # b 
  # 2 
  s2["b"]
  # b 
  # 2

etc.
Ted.

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Date: 17-Nov-09                                       Time: 23:26:25
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