[R] Converting text to numbers

[jim holtman]

> x <- read.table('clipboard', header=T, as.is=T)
> str(x)
`data.frame':   7 obs. of  2 variables:
 $ FCT: chr  "1" "2" "3-" "3" ...
 $ OBS: chr  "5" "4" "3+" "3" ...
#  define your conversion
> x.c <- c('1'=1, '2'=2, '3'=3, '3-'=2, '3+'=5, '4-'=3, '4'=6, '5'=7)
> x.c[x$FCT]
 1  2 3-  3 3+  4  5
 1  2  2  3  5  6  7
> x$FCT1 <- x.c[x$FCT]
> x$OBS1 <- x.c[x$OBS]
> x
  FCT OBS FCT1 OBS1
1   1   5    1    7
2   2   4    2    6
3  3-  3+    2    5
4   3   3    3    3
5  3+  3-    5    2
6   4   2    6    2
7   5   1    7    1
> str(x)
`data.frame':   7 obs. of  4 variables:
 $ FCT : chr  "1" "2" "3-" "3" ...
 $ OBS : chr  "5" "4" "3+" "3" ...
 $ FCT1: num  1 2 2 3 5 6 7
 $ OBS1: num  7 6 5 3 2 2 1
> x$FCT1 - x$OBS1
[1] -6 -4 -3  0  3  4  6
>


On 9/27/06, Dan Chan <dchan at gfc.state.ga.us> wrote:
> Hi,
>
> I have Forecast Class and Observed Class in a data matrix as below.
>
> > Sample1
>  FCT OBS
> 1   1  5
> 2   2   4
> 3  3-  3+
> 4   3   3
> 5  3+  3-
> 6   4   2
> 7   5   1
>
> I want to find the difference between Observed and Forecast Classes.
> How can I get this done?
>
> I tried to following to convert the 1 through 5 classes, to 1 through 7
> for both OBS and FCT column.
> > Sample1$OBS2 <- Sample1$OBS
> > levels(Sample1$OBS2) <- sub('5',7,levels(Sample1$OBS2),fixed=TRUE)
> > levels(Sample1$OBS2) <- sub('4',6,levels(Sample1$OBS2),fixed=TRUE)
> > levels(Sample1$OBS2) <- sub('3+',5,levels(Sample1$OBS2), fixed=TRUE)
> > levels(Sample1$OBS2) <- sub('3',4,levels(Sample1$OBS2),fixed=TRUE)
> > levels(Sample1$OBS2) <- sub('4-',3,levels(Sample1$OBS2),fixed=TRUE)
> > Sample1
>  FCT OBS FCT2 OBS2
> 1   1  5     1   7
> 2   2   4    2    6
> 3  3-  3+    3    5
> 4   3   3    4    4
> 5  3+  3-    5    3
> 6   4   2    6    2
> 7   5   1    7    1
>
> All looks good, but as I do the following, I encounter an error.
> > Sample1$OBS2- Sample1$FCT2
> [1] NA NA NA NA NA NA NA
> Warning message:
> - not meaningful for factors in: Ops.factor(Sample1$OBS2, Sample1$FCT2)
>
> Then, I tried to convert them to numbers using the following.
> > Sample1$FCT2 <- as.numeric(Sample1$FCT2)
> > Sample1$OBS2 <- as.numeric(Sample1$OBS2)
> > Sample1
>  FCT OBS FCT2 OBS2
> 1   1  5     1    7
> 2   2   4    2    6
> 3  3-  3+    4    5
> 4   3   3    3    3
> 5  3+  3-    5    4
> 6   4   2    6    2
> 7   5   1    7    1
>
> Sample1$FCT2[3] and Sample1$FCT2[4] switched values.
>
> I think it has something to do with the following:
> > Sample1$OBS
> [1] 5  4  3+ 3  3- 2   1
> Levels:  1 2 3 3- 3+ 4 5
>
> But, I don't know why and how to fix it.
>
> Any ideas?
>
> Thank you.
>
>
>
> Daniel Chan
> Meteorologist
> Georgia Forestry Commission
> P O Box 819
> Macon, GA
> 31202
> Tel: 478-751-3508
> Fax: 478-751-3465
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

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