Converting R time column to specific strings

Question

I have a column representing time in a data frame in R.

when I call the str() function on the column it says something like this

>str(df2$Time)
 Factor w/ 1441 levels "","00:01","00:02","00:03",..: 1086 1096 1111 and so on

The thing is I want to conver this column into string type such that if the time is less than 12:00, it should get modified to the string "moring" , if time is between 12:00 and 6:00 , it is "daylight" and so on.

The first step I thought was to convert this vector to time type of column of data frame, so I used chron function.

I typed the following command,

>df2$Time<-chron(times=df2$Time,format=c('h:m'))
 Error in convert.times(times., fmt) : format h:m may be incorrect
 In addition: Warning message:
In is.na(out$s) : is.na() applied to non-(list or vector) of type 'NULL"

so I guessed I should have added second parameter in format so I tried the following :

df2$Time<-chron(time=df2$Time,format=c('h:m:s'))

But still got the same error

I know this is just the first step, may be my approach too is wrong. Can anyone suggest me how to convert these time data cells to morning, evening , night etc.

Any help is much appreciated.

Answer 1

Use chron's "times" class and cut:

library(chron)

# data in reproducible form
df2 <- data.frame(Times = c("00:01","12:02","19:03"))

df2$Times <- times(paste0(df2$Times, ":00")) # append a chron "times" class column
breaks <- c(0, 12, 18, 24) / 24 # times are internally fractions of a day
labels <- c("morning", "daylight", "evening")
df2$ind <- cut(df2$Times, breaks, labels, include.lowest = TRUE)

which gives:

> df2
     Times      ind
1 00:01:00  morning
2 12:02:00 daylight
3 19:03:00  evening

Next time please supply your data in reproducible form.

REVISED Minor simplification and fixed typo.

Answer 2

The same thing with lubridate (sorry Joran, i like this package), and functions hour and hm:

Time <- hour(hm("13:24","19:32","3:45","08:25", "21:45", "11:13", "00:00"))
your_breaks <- hour(hm("00:00", "6:00", "12:00", "18:00", "23:59"))
your_labels <- c("Night", "Morning", "Afternoon", "Evening")
cut(x=Time, breaks=your_breaks, labels=your_labels, include.lowest=TRUE)

[1] Afternoon Evening   Night     Morning   Evening   Morning   Night