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matlab serial date to r

4 messages · Christoph Schlächter, Brian Ripley, Jeff Newmiller +1 more

Original
Brian Ripley
# 
See ?as.Date.

I am guessing these are days and fractional days.  Try

x <- 7.356000000813091e5
as.POSIXct((x - 719529)*86400, origin = "1970-01-01")
On 25/06/2014 14:56, Christoph Schl?chter wrote:

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      Jeff Newmiller
    

    

      
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I think the character format for this data is the most versatile and clear option. You do have to prevent the R input function (read.csv? read.table?) from converting it to factor when you read it in, but then you can use as.POSIXct with a format argument (see ?strptime) to obtain useful timestamp values in R. You also need to be clear about time zones, but that is true regardless of the software you use.
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On June 25, 2014 6:56:38 AM PDT, "Christoph Schl?chter" <christoph.schlaechter at gmail.com> wrote:

            

      
      
      
    

        

      
      
    

  
  


  


      

    

    

      
      

        


  

        

      arun
    

    

      
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Hi,
May be this helps:

dat <- read.table(text="7.356000000813091
? 7.356000000956856
? 7.356000001305921
? 7.356000001654985
? 7.356000002004049
? 7.356000002353113
? 7.356000002702178
? 7.356000003397179
? 7.356000004092182
? 7.356000004787183
? 7.356000005482185
? 7.356000006177187
? 7.356000006940080
? 7.356000007702975
? 7.356000008465869
? 7.356000009228763
? 7.356000009991657
? 7.356000010754551
? 7.356000011517445
? 7.356000012280339
? 7.356000013085329",sep="",header=F, colClasses="character")
library(chron)
t1 <- chron(1.0e+05 *as.numeric(dat[,1])) -719529
format(as.POSIXct(paste(as.Date(dates(t1)), times(t1)%%1)),"%m-%b-%Y %H:%M:%S")


A.K.

        
On Wednesday, June 25, 2014 10:00 AM, Christoph Schl?chter <christoph.schlaechter at gmail.com> wrote:

        
Hi,

I have a matlab variable as serial date (class double) in the form
'dd-mmm-yyyy HH:MM:SS'.

format long
disp( tx(40:60,1) )

1.0e+05 *

?  7.356000000813091
?  7.356000000956856
?  7.356000001305921
?  7.356000001654985
?  7.356000002004049
?  7.356000002353113
?  7.356000002702178
?  7.356000003397179
?  7.356000004092182
?  7.356000004787183
?  7.356000005482185
?  7.356000006177187
?  7.356000006940080
?  7.356000007702975
?  7.356000008465869
?  7.356000009228763
?  7.356000009991657
?  7.356000010754551
?  7.356000011517445
?  7.356000012280339
?  7.356000013085329

It should be the same as

datestr( tx(40:60,1), 0)

01-Jan-2014 00:00:07
01-Jan-2014 00:00:08
01-Jan-2014 00:00:11
01-Jan-2014 00:00:14
01-Jan-2014 00:00:17
01-Jan-2014 00:00:20
01-Jan-2014 00:00:23
01-Jan-2014 00:00:29
01-Jan-2014 00:00:35
01-Jan-2014 00:00:41
01-Jan-2014 00:00:47
01-Jan-2014 00:00:53
01-Jan-2014 00:00:59
01-Jan-2014 00:01:06
01-Jan-2014 00:01:13
01-Jan-2014 00:01:19
01-Jan-2014 00:01:26
01-Jan-2014 00:01:32
01-Jan-2014 00:01:39
01-Jan-2014 00:01:46
01-Jan-2014 00:01:53

I can easily convert it with Matlab but then I will obtain a character
format which is useless. I can also make use of cellstr(datestr(tx(:,1),
0)) but then I can't save it in ASCII file.

The origin of the Matlab format is supposed to be "0000-00-00". This is the
only origin which results in "2014-01-01" which is my actual start date.

Can somebody please tell me how I can simply convert serial datetime to
datetime in R.

Thanks in advance.

All the best,

Christoph

??? [[alternative HTML version deleted]]

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