Try as.character like the following shows.
> dfx <- data.frame(
+ group = c(rep('A', 8), rep('B', 15), rep('C', 6)),
+ sex = sample(c("M", "F"), size = 29, replace = TRUE),
+ age = runif(n = 29, min = 18, max = 54))
> dfx
group sex age
1 A M 41.35554346
2 A F 47.73245469
3 A F 42.97870796
4 A M 52.51180396
5 A F 46.72228944
6 A M 48.64668630
7 A M 36.07894452
8 A M 26.96805121
9 B M 30.67208692
10 B M 45.09322672
11 B M 31.86601692
12 B F 53.28861780
13 B M 27.74271305
14 B F 52.05845066
15 B F 18.94612430
16 B M 48.66673378
17 B F 53.07004762
18 B F 48.15222416
19 B M 32.17737802
20 B M 37.02122907
21 B M 39.31442046
22 B M 27.90392578
23 B M 44.70562356
24 C F 53.43127126
25 C M 49.85362283
26 C M 40.40779822
27 C F 31.41189728
28 C M 47.49351314
29 C M 46.34333618
> summary(dfx)
group sex age
A: 8 F:10 Min. :18.94612
B:15 M:19 1st Qu.:32.17738
C: 6 Median :44.70562
Mean :41.46947
3rd Qu.:48.64669
Max. :53.43127
> dfx$group <- *as.character*(dfx$group)
> summary(dfx)
group sex age
Length:29 F:10 Min. :18.94612
Class :character M:19 1st Qu.:32.17738
Mode :character Median :44.70562
Mean :41.46947
3rd Qu.:48.64669
Max. :53.43127
> dfx
group sex age
1 A M 41.35554346
2 A F 47.73245469
3 A F 42.97870796
4 A M 52.51180396
5 A F 46.72228944
6 A M 48.64668630
7 A M 36.07894452
8 A M 26.96805121
9 B M 30.67208692
10 B M 45.09322672
11 B M 31.86601692
12 B F 53.28861780
13 B M 27.74271305
14 B F 52.05845066
15 B F 18.94612430
16 B M 48.66673378
17 B F 53.07004762
18 B F 48.15222416
19 B M 32.17737802
20 B M 37.02122907
21 B M 39.31442046
22 B M 27.90392578
23 B M 44.70562356
24 C F 53.43127126
25 C M 49.85362283
26 C M 40.40779822
27 C F 31.41189728
28 C M 47.49351314
29 C M 46.34333618
> dfx$sex <- *as.character*(dfx$sex)
> summary(dfx)
group sex age
Length:29 Length:29 Min. :18.94612
Class :character Class :character 1st Qu.:32.17738
Mode :character Mode :character Median :44.70562
Mean :41.46947
3rd Qu.:48.64669
Max. :53.43127
> class(dfx$group)
[1] "character"
> dfx$group
[1] "A" "A" "A" "A" "A" "A" "A" "A" "B" "B" "B" "B" "B" "B" "B" "B" "B" "B"
"B" "B" "B" "B" "B" "C"
[25] "C" "C" "C" "C" "C"
> class(dfx$sex)
[1] "character"
> dfx$sex
[1] "M" "F" "F" "M" "F" "M" "M" "M" "M" "M" "M" "F" "M" "F" "F" "M" "F" "F"
"M" "M" "M" "M" "M" "F"
[25] "M" "M" "F" "M" "M"
>
--
View this message in context:
http://r.789695.n4.nabble.com/format-selected-columns-in-dataframe-as-character-tp4703863p4703878.html
Sent from the R help mailing list archive at Nabble.com.
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
