[R] creating a factor

[Peter Dalgaard]

Simon Hosking <simon.hosking at general.monash.edu.au> writes:

> Hi list,
> I'd like to make a factor with seven 1s and three 2s using the
> factor() function. 
> That is,
> 
> 1
> 1
> 1
> 1
> 1
> 1
> 1
> 2
> 2
> 2
>  
> 
> I will then bind this factor to the matrix below using cbind.data.frame().
> 
> 0.56	0.48
> 0.22	0.59
> 0.32	0.64
> 0.26	0.60
> 0.25	0.38
> 0.24	0.45
> 0.56	0.67
> 0.78	0.97
> 0.87	0.79
> 0.82	0.85
> 
> 
> 
> I am new to R and have been using various manuals and have made many attempts without success
> any help appreciated.
> thanks,
> Simon


> f <- factor(scan())
1: 1
2: 1
3: 1
4: 1
5: 1
6: 1
7: 1
8: 2
9: 2
10: 2
11:
Read 10 items


> df <- read.table(stdin())
0: 0.56 0.48
1: 0.22 0.59
2: 0.32 0.64
3: 0.26 0.60
4: 0.25 0.38
6: 0.24 0.45
7: 0.56 0.67
8: 0.78 0.97
9: 0.87 0.79
10: 0.82 0.85
11:


> cbind(df,f)
     V1   V2 f
1  0.56 0.48 1
2  0.22 0.59 1
3  0.32 0.64 1
4  0.26 0.60 1
5  0.25 0.38 1
6  0.24 0.45 1
7  0.56 0.67 1
8  0.78 0.97 2
9  0.87 0.79 2
10 0.82 0.85 2

> summary(cbind(df,f))
       V1               V2         f
 Min.   :0.2200   Min.   :0.3800   1:7
 1st Qu.:0.2525   1st Qu.:0.5075   2:3
 Median :0.4400   Median :0.6200
 Mean   :0.4880   Mean   :0.6420
 3rd Qu.:0.7250   3rd Qu.:0.7600
 Max.   :0.8700   Max.   :0.9700


so what was the problem?? 

I suspect your df was a matrix, not a data frame: just take
as.data.frame first. Otherwise, you'll find that f gets converted to
numeric.

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907