[R] converting time data in R

[PIKAL Petr]

Hi

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of R Novice
> Sent: Tuesday, February 18, 2014 9:44 AM
> To: r-help at r-project.org
> Subject: [R] converting time data in R
>
> Respected R veterans and experts,
>
>
>
> 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
>

You have some empty levels (cells) and it seems that not all data are in xx:yy format, so you need to repair it.


> 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.

You could transfer it to POSIX class and manipulate with logical operations. Maybe chron object can also be used for such comparisons.

>
> 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"

see my first comment.

Regards
Petr

>
> 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.
>
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>
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