How to check order factor variable in R

Question

I have factor variables in a data frame. I want some of them to be ordered (such as education) and some of them unordered (such as sex).

I create some of the variables and some get created automatically.

Is there a way to check that? Maybe using str() or some other method?

If you're unsure how to do that, consider reading [ask] and [how to make a reproducible example](http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example) — Heroka, Oct 20 '15 at 09:06
`str` will show you if the factors are ordered, yes. It will call it `Ord.factor`. — David Arenburg, Oct 20 '15 at 09:10
Thank David Arenburg and if it not ordered what it will show? — itay friedman, Oct 20 '15 at 19:56

score 1 · Answer 1 · answered Oct 21 '15 at 06:38

So after long searched i realize it simply answer all my factor was unordered. ordered factor sign by greater then sign (>) and unordered there is no sign between levels as shown in this code

> orderEduc[1:6]
[1] high        junior-high high        elementary  high        junior-high
Levels: elementary < junior-high < high < academic

> finalDF$eduction[1:6]
[1] high        junior-high high        elementary  high        junior-high
Levels: elementary junior-high high academic

one web page that help me understand was http://www.ats.ucla.edu/stat/r/modules/factor_variables.htm

leoluyi · Answer 2 · 2015-10-29T04:05:49.263

0

You can simply use this for checking class of each variable for data.frame.

iris$Sepal.Length <- as.ordered(iris$Sepal.Length)
sapply(iris, class)

# $Sepal.Length
# [1] "ordered" "factor" 
# 
# $Sepal.Width
# [1] "numeric"
# 
# $Petal.Length
# [1] "numeric"
# 
# $Petal.Width
# [1] "numeric"
# 
# $Species
# [1] "factor"

edited Oct 29 '15 at 04:05

answered Oct 20 '15 at 09:11

leoluyi

942
1
7
14

1

but can i distinguish between ordered factor and not ordered one? – itay friedman Oct 20 '15 at 19:58
There's an extra class `ordered` for ordered factor. – leoluyi Oct 29 '15 at 04:07

score 0 · Answer 3 · answered Aug 31 '23 at 09:42

The function is.ordered() returns TRUE when its argument is an ordered factor and FALSE otherwise.

Following the example by @leouyi:

iris$Sepal.Length <- is.ordered(iris$Sepal.Length)

sapply(iris, is.ordered)

Sepal.Length  Sepal.Width Petal.Length  Petal.Width      Species    
        TRUE        FALSE        FALSE        FALSE        FALSE

How to check order factor variable in R

3 Answers3