Building factors across two columns, is this possible?

Hello,

You can do what you want, but the coding of factors starts at 1 not at 0.


dat <- read.table(text="
V1    V2       V3
1   sun  moon    stars
2 stars  moon      sun
3   cat   dog   catdog
4   dog  moon      sun
5  bird plane superman
6  1000   dog     2000
", header = TRUE)

levs <- unique(unlist(dat))

dat$V1 <- factor(dat$V1, levels = levs)
dat$V2 <- factor(dat$V2, levels = levs)
dat$V3 <- factor(dat$V3, levels = levs)

str(dat)
'data.frame':   6 obs. of  3 variables:
 $ V1: Factor w/ 11 levels "sun","stars",..: 1 2 3 4 5 6
 $ V2: Factor w/ 11 levels "sun","stars",..: 7 7 4 7 8 4
 $ V3: Factor w/ 11 levels "sun","stars",..: 2 1 9 1 10 11


Hope this helps,

Rui Barradas
Em 24-11-2012 07:33, Brian Feeny escreveu:

To clarify on my previous post, here is a representation of what I am 
trying to accomplish:

I would like every unique value in either column to be assigned a 
number so like so:

     V1    V2       V3
1   sun  moon    stars
2 stars  moon      sun
3   cat   dog   catdog
4   dog  moon      sun
5  bird plane superman
6  1000   dog     2000

Level            Value
sun            ->    0
stars        ->    1
cat            ->    2
dog            ->    3
bird            ->    4
1000        ->    5
moon        ->    6
plane        ->    7
catdog        ->    8
superman    ->    9
2000        ->   10
etc
etc

so internally its represented as:

     V1    V2       V3
1   0        6    1
2   1        6    0
3   2        3    8
4   3        6    0
5   4        7    9
6   5        3    10

does this make sense?  I am hoping there is a way to accomplish this.

Brian

On Nov 23, 2012, at 11:42 PM, Brian Feeny <bfeeny at mac.com> wrote:

I am trying to make it so two columns with similar data use the same 
internal numbers for same factors, here is the example:

read.csv("test.csv",header =FALSE,sep=",")

     V1    V2       V3
1   sun  moon    stars
2 stars  moon      sun
3   cat   dog   catdog
4   dog  moon      sun
5  bird plane superman
6  1000   dog     2000

data <- read.csv("test.csv",header =FALSE,sep=",")
str(data)

'data.frame':    6 obs. of  3 variables:
$ V1: Factor w/ 6 levels "1000","bird",..: 6 5 3 4 2 1
$ V2: Factor w/ 3 levels "dog","moon","plane": 2 2 1 2 3 1
$ V3: Factor w/ 5 levels "2000","catdog",..: 3 4 2 4 5 1

as.numeric(data$V1)

[1] 6 5 3 4 2 1

as.numeric(data$V2)

[1] 2 2 1 2 3 1

as.factor(data$V1)

[1] sun   stars cat   dog   bird  1000
Levels: 1000 bird cat dog stars sun

as.factor(data$V2)

[1] moon  moon  dog   moon  plane dog
Levels: dog moon plane


So notice "dog" is 4 in V1, yet its 1 in V2.  Is there a way, either 
on import, or after, to have factors computed for both columns and 
assigned
the same internal values?

Brian