R help - Mar 2012 - Converting factor data into Date-time format

Dear R-user,

I have read a dataset from .csv file into R. This dataset includes one
column containing some data in 'date and time' format, e.g.
'dd/mm/yyyy
hh:mm'.

These data were automatically read and saved as 'factor' in R. When I
was
trying to produce some plots (such as time series) with the above 'date and
time' on x-axis,  it caused some disodering problem, e.g. 1st of March 2012
is in front of 10th of Feb. 2012 (if the data is from 10th Feb. 2012 to 1st
of March 2012). I understand that I might have to convert them from
'factor' to 'date' first, so I tried using 'as.date'.
But this method seems
only work for data in format of  'd/m/y' and no further option that
allows
me to add hours and minutes.

I checked online for other methods such as 'as.POSIX' and
'strptime' but
none of them seem to offer me a quick solution.

Please note that the data I received is recorded every 10 minutes so they
are saved in the form of  'dd/mm/yyyy hh:mm', e.g. I only have data
measured up to 'minute' NOT to  'second'. Are there any direct
solution
that I can solve this issue??


Many thanks in advance!
HJ

	[[alternative HTML version deleted]]

as.POSIXct(as.character(FACTORHERE), format = "%d/%m/%Y %H:%M")

Michael

On Tue, Mar 13, 2012 at 12:20 PM, Haojie Yan <yhj204 at googlemail.com>
wrote:
> Dear R-user,
>
> I have read a dataset from .csv file into R. This dataset includes one
> column containing some data in 'date and time' format, e.g.
'dd/mm/yyyy
> hh:mm'.
>
> These data were automatically read and saved as 'factor' in R. When
I was
> trying to produce some plots (such as time series) with the above 'date
and
> time' on x-axis, ?it caused some disodering problem, e.g. 1st of March
2012
> is in front of 10th of Feb. 2012 (if the data is from 10th Feb. 2012 to 1st
> of March 2012). I understand that I might have to convert them from
> 'factor' to 'date' first, so I tried using
'as.date'. But this method seems
> only work for data in format of ?'d/m/y' and no further option that
allows
> me to add hours and minutes.
>
> I checked online for other methods such as 'as.POSIX' and
'strptime' but
> none of them seem to offer me a quick solution.
>
> Please note that the data I received is recorded every 10 minutes so they
> are saved in the form of ?'dd/mm/yyyy hh:mm', e.g. I only have data
> measured up to 'minute' NOT to ?'second'. Are there any
direct solution
> that I can solve this issue??
>
>
> Many thanks in advance!
> HJ
>
> ? ? ? ?[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> 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.

On Tue, Mar 13, 2012 at 12:20 PM, Haojie Yan <yhj204 at googlemail.com>
wrote:
> Dear R-user,
>
> I have read a dataset from .csv file into R. This dataset includes one
> column containing some data in 'date and time' format, e.g.
'dd/mm/yyyy
> hh:mm'.
>
> These data were automatically read and saved as 'factor' in R. When
I was
> trying to produce some plots (such as time series) with the above 'date
and
> time' on x-axis, ?it caused some disodering problem, e.g. 1st of March
2012
> is in front of 10th of Feb. 2012 (if the data is from 10th Feb. 2012 to 1st
> of March 2012). I understand that I might have to convert them from
> 'factor' to 'date' first, so I tried using
'as.date'. But this method seems
> only work for data in format of ?'d/m/y' and no further option that
allows
> me to add hours and minutes.
>
> I checked online for other methods such as 'as.POSIX' and
'strptime' but
> none of them seem to offer me a quick solution.
>
> Please note that the data I received is recorded every 10 minutes so they
> are saved in the form of ?'dd/mm/yyyy hh:mm', e.g. I only have data
> measured up to 'minute' NOT to ?'second'. Are there any
direct solution
> that I can solve this issue??
See Example 6 in the document Reading Data in zoo:
http://cran.r-project.org/package=zoo

-- 
Statistics & Software Consulting
GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com

Just a little typo: see below.

On Tue, Mar 13, 2012 at 1:00 PM, Haojie Yan <yhj204 at googlemail.com>
wrote:
> Dear Michael,
>
> Thanks a lot for your hints.
>
> I have just had a try as below but still got back some error messages as
> shown:
>
> The?object containing the 'date_time' data is?named
'INTERVAL_END_TIME'?and
> and wanted to plot it against another?variable 'CHANNEL_01' (data
type:
> numerical).
>
>
> As you suggested I did the following...
>
> (1) Converting 'INTERVAL_END_TIME' into charactor first and name it
> 'DATE_TIME_1';
> (2) Converting ?'DATE_TIME_1' into "POSIXlt"
"POSIXt" type data
>
> But, seems it doesnt work well and I got 'NA's for all of them...
>
> Any thoughts??
>
> Many thanks again!
> HJ
>
>
>> INTERVAL_END_TIME[1:10]
> ?[1] 20/02/2012 00:10 20/02/2012 00:20 20/02/2012 00:30 20/02/2012 00:40
> 20/02/2012 00:50
> ?[6] 20/02/2012 01:00 20/02/2012 01:10 20/02/2012 01:20 20/02/2012 01:30
> 20/02/2012 01:40
> 1584 Levels: 01/03/2012 00:00 01/03/2012 00:10 01/03/2012 00:20 ...
> 29/02/2012 23:50
>
>> class(INTERVAL_END_TIME)
> [1] "factor"
>
>> DATE_TIME_1<-as.character(INTERVAL_END_TIME)
>
>> DATE_TIME_1[1:10]
> ?[1] "20/02/2012 00:10" "20/02/2012 00:20"
"20/02/2012 00:30" "20/02/2012
> 00:40"
> ?[5] "20/02/2012 00:50" "20/02/2012 01:00"
"20/02/2012 01:10" "20/02/2012
> 01:20"
> ?[9] "20/02/2012 01:30" "20/02/2012 01:40"
>
>> class(DATE_TIME_1)
> [1] "character"
>
>> DATE_TIME_2<-as.POSIXlt(DATE_TIME_1,format="%d/%m/%y
%H:%M")
This needs to be a capital "Y" as in my original post.

e.g.,

x <- c("20/02/2012 00:10", "20/02/2012 00:20",
"20/02/2012 00:30",
"20/02/2012 00:40")

as.POSIXct(x, format = "%d/%m/%y %H:%M") # No good :-(
as.POSIXct(x, format = "%d/%m/%Y %H:%M") # Good!



Michael
>
>> DATE_TIME_2[1:10]
> ?[1] NA NA NA NA NA NA NA NA NA NA
>
>> class(DATE_TIME_2)
> [1] "POSIXlt" "POSIXt"
>
>> plot(DATE_TIME_2,CHANNEL_01)
> Error in plot.window(...) : need finite 'xlim' values
> In addition: Warning messages:
> 1: In min(x) : no non-missing arguments to min; returning Inf
> 2: In max(x) : no non-missing arguments to max; returning -Inf
>>
>
> On Tue, Mar 13, 2012 at 4:30 PM, R. Michael Weylandt
> <michael.weylandt at gmail.com> wrote:
>>
>> as.POSIXct(as.character(FACTORHERE), format = "%d/%m/%Y
%H:%M")
>>
>> Michael
>>
>> On Tue, Mar 13, 2012 at 12:20 PM, Haojie Yan <yhj204 at
googlemail.com>
>> wrote:
>> > Dear R-user,
>> >
>> > I have read a dataset from .csv file into R. This dataset includes
one
>> > column containing some data in 'date and time' format,
e.g. 'dd/mm/yyyy
>> > hh:mm'.
>> >
>> > These data were automatically read and saved as 'factor'
in R. When I
>> > was
>> > trying to produce some plots (such as time series) with the above
'date
>> > and
>> > time' on x-axis, ?it caused some disodering problem, e.g. 1st
of March
>> > 2012
>> > is in front of 10th of Feb. 2012 (if the data is from 10th Feb.
2012 to
>> > 1st
>> > of March 2012). I understand that I might have to convert them
from
>> > 'factor' to 'date' first, so I tried using
'as.date'. But this method
>> > seems
>> > only work for data in format of ?'d/m/y' and no further
option that
>> > allows
>> > me to add hours and minutes.
>> >
>> > I checked online for other methods such as 'as.POSIX' and
'strptime' but
>> > none of them seem to offer me a quick solution.
>> >
>> > Please note that the data I received is recorded every 10 minutes
so
>> > they
>> > are saved in the form of ?'dd/mm/yyyy hh:mm', e.g. I only
have data
>> > measured up to 'minute' NOT to ?'second'. Are
there any direct solution
>> > that I can solve this issue??
>> >
>> >
>> > Many thanks in advance!
>> > HJ
>> >
>> > ? ? ? ?[[alternative HTML version deleted]]
>> >
>>
>> > ______________________________________________
>> > R-help at r-project.org mailing list
>> > 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.
>
>

No problem.

A pro-tip for future posts: the dput() function creates a plain text
representation of the data in question which is great for email and is
nicely copy-and-pasteable. It wasn't so much a thing here, but for
large or complicated data sets, the regular console printout doesn't
always reveal all the details in play. (This can be particularly nasty
when dealing with time objects)

Best,

Michael Weylandt


On Tue, Mar 13, 2012 at 1:28 PM, Haojie Yan <yhj204 at googlemail.com>
wrote:
> Hi Michael!!!
>
> As a first time R-help user I just wanted to say THANKS A MILLION!!!!!!!
for
> your prompt and very helpful reply!!!
>
> Still can not believe this annoying issue can be resolved that quickly!!!
>
> Brilliant-will visit this forum soon!!
> HJ
>
> On Tue, Mar 13, 2012 at 5:09 PM, R. Michael Weylandt
> <michael.weylandt at gmail.com> wrote:
>>
>> Just a little typo: see below.
>>
>> On Tue, Mar 13, 2012 at 1:00 PM, Haojie Yan <yhj204 at
googlemail.com> wrote:
>> > Dear Michael,
>> >
>> > Thanks a lot for your hints.
>> >
>> > I have just had a try as below but still got back some error
messages as
>> > shown:
>> >
>> > The?object containing the 'date_time' data is?named
>> > 'INTERVAL_END_TIME'?and
>> > and wanted to plot it against another?variable
'CHANNEL_01' (data type:
>> > numerical).
>> >
>> >
>> > As you suggested I did the following...
>> >
>> > (1) Converting 'INTERVAL_END_TIME' into charactor first
and name it
>> > 'DATE_TIME_1';
>> > (2) Converting ?'DATE_TIME_1' into "POSIXlt"
"POSIXt" type data
>> >
>> > But, seems it doesnt work well and I got 'NA's for all of
them...
>> >
>> > Any thoughts??
>> >
>> > Many thanks again!
>> > HJ
>> >
>> >
>> >> INTERVAL_END_TIME[1:10]
>> > ?[1] 20/02/2012 00:10 20/02/2012 00:20 20/02/2012 00:30 20/02/2012
00:40
>> > 20/02/2012 00:50
>> > ?[6] 20/02/2012 01:00 20/02/2012 01:10 20/02/2012 01:20 20/02/2012
01:30
>> > 20/02/2012 01:40
>> > 1584 Levels: 01/03/2012 00:00 01/03/2012 00:10 01/03/2012 00:20
...
>> > 29/02/2012 23:50
>> >
>> >> class(INTERVAL_END_TIME)
>> > [1] "factor"
>> >
>> >> DATE_TIME_1<-as.character(INTERVAL_END_TIME)
>> >
>> >> DATE_TIME_1[1:10]
>> > ?[1] "20/02/2012 00:10" "20/02/2012 00:20"
"20/02/2012 00:30"
>> > "20/02/2012
>> > 00:40"
>> > ?[5] "20/02/2012 00:50" "20/02/2012 01:00"
"20/02/2012 01:10"
>> > "20/02/2012
>> > 01:20"
>> > ?[9] "20/02/2012 01:30" "20/02/2012 01:40"
>> >
>> >> class(DATE_TIME_1)
>> > [1] "character"
>> >
>> >> DATE_TIME_2<-as.POSIXlt(DATE_TIME_1,format="%d/%m/%y
%H:%M")
>>
>> This needs to be a capital "Y" as in my original post.
>>
>> e.g.,
>>
>> x <- c("20/02/2012 00:10", "20/02/2012 00:20",
"20/02/2012 00:30",
>> "20/02/2012 00:40")
>>
>> as.POSIXct(x, format = "%d/%m/%y %H:%M") # No good :-(
>> as.POSIXct(x, format = "%d/%m/%Y %H:%M") # Good!
>>
>>
>>
>> Michael
>>
>> >
>> >> DATE_TIME_2[1:10]
>> > ?[1] NA NA NA NA NA NA NA NA NA NA
>> >
>> >> class(DATE_TIME_2)
>> > [1] "POSIXlt" "POSIXt"
>> >
>> >> plot(DATE_TIME_2,CHANNEL_01)
>> > Error in plot.window(...) : need finite 'xlim' values
>> > In addition: Warning messages:
>> > 1: In min(x) : no non-missing arguments to min; returning Inf
>> > 2: In max(x) : no non-missing arguments to max; returning -Inf
>> >>
>> >
>> > On Tue, Mar 13, 2012 at 4:30 PM, R. Michael Weylandt
>> > <michael.weylandt at gmail.com> wrote:
>> >>
>> >> as.POSIXct(as.character(FACTORHERE), format = "%d/%m/%Y
%H:%M")
>> >>
>> >> Michael
>> >>
>> >> On Tue, Mar 13, 2012 at 12:20 PM, Haojie Yan <yhj204 at
googlemail.com>
>> >> wrote:
>> >> > Dear R-user,
>> >> >
>> >> > I have read a dataset from .csv file into R. This dataset
includes
>> >> > one
>> >> > column containing some data in 'date and time'
format, e.g.
>> >> > 'dd/mm/yyyy
>> >> > hh:mm'.
>> >> >
>> >> > These data were automatically read and saved as
'factor' in R. When I
>> >> > was
>> >> > trying to produce some plots (such as time series) with
the above
>> >> > 'date
>> >> > and
>> >> > time' on x-axis, ?it caused some disodering problem,
e.g. 1st of
>> >> > March
>> >> > 2012
>> >> > is in front of 10th of Feb. 2012 (if the data is from
10th Feb. 2012
>> >> > to
>> >> > 1st
>> >> > of March 2012). I understand that I might have to convert
them from
>> >> > 'factor' to 'date' first, so I tried
using 'as.date'. But this method
>> >> > seems
>> >> > only work for data in format of ?'d/m/y' and no
further option that
>> >> > allows
>> >> > me to add hours and minutes.
>> >> >
>> >> > I checked online for other methods such as
'as.POSIX' and 'strptime'
>> >> > but
>> >> > none of them seem to offer me a quick solution.
>> >> >
>> >> > Please note that the data I received is recorded every 10
minutes so
>> >> > they
>> >> > are saved in the form of ?'dd/mm/yyyy hh:mm',
e.g. I only have data
>> >> > measured up to 'minute' NOT to ?'second'.
Are there any direct
>> >> > solution
>> >> > that I can solve this issue??
>> >> >
>> >> >
>> >> > Many thanks in advance!
>> >> > HJ
>> >> >
>> >> > ? ? ? ?[[alternative HTML version deleted]]
>> >> >
>> >>
>> >> > ______________________________________________
>> >> > R-help at r-project.org mailing list
>> >> > 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.
>> >
>> >
>
>