levels

On Jul 15, 2020, at 4:31 AM, andy elprama <andy.elprama at gmail.com> wrote:

Dear R-users,

Something strange happened within the command "levels"

R version 3.6.1
name <- c("a","b","c")
values <- c(1,2,3)
data <- data.frame(name,values)
levels(data$name)
[1] "a" "b" "c"

R version 4.0
name <- c("a","b","c")
values <- c(1,2,3)
data <- data.frame(name,values)
levels(data$name)
[1] NULL

What is happening here?

Hi,

The default value for 'stringsAsFactors' for data.frame() and read.table() changed from TRUE to FALSE in version 4.0.0, per the news() file:

"R now uses a stringsAsFactors = FALSE default, and hence by default no longer converts strings to factors in calls to data.frame() and read.table()."


Using 4.0.2:

data <- data.frame(name, values, stringsAsFactors = TRUE)

levels(data$name)

[1] "a" "b" "c"


If you see behavioral changes from one version of R to another, especially major version increments, check the news() file.

Regards,

Marc Schwartz