I have some integers (timestamps) and I want to convert them into time intervals (time deltas). How can I do that in R?
Something like this:
strptime(37998530.34, format="%d %H:%M")
This R code returns with error:
difftime(37998530.34, 0)
In Python I can use this code:
datetime.timedelta(0, 37998530.34)
And the result is:
datetime.timedelta(439, 68930, 340000)
439 days, 19:08:50.340000
Thank you!
In R you need to specify the origin for the date conversion. Assuming your value is the number of seconds use this function:
as.POSIXlt(37998530.34, origin="1970-01-01")
#[1] "1971-03-16 14:08:50 EST"
as.POSIXlt function also has an option to specify the desired timezone (tz= )
The following code:
difftime(as.POSIXlt(37998530.34, origin="1970-01-01"), as.POSIXlt(0, origin="1970-01-01"), units=c('days'))
has the result:
Time difference of 439.8 days
Related
Have an large data frame where there's 2 columns (POSIXct) and need to calculate length of ride.
Dates are formatted as follows:
format: "2020-10-31 19:39:43"
Can use the difftime function, correct?
Thanks
Given your data is using the correct POSIXct format you can simply subtract two dates to get the difference. No need for additional functions.
date1 <- as.POSIXct(strptime("2020-10-31 19:39:43", format = "%Y-%m-%d %H:%M:%OS"))
date2 <- as.POSIXct(strptime("2020-10-31 19:20:43", format = "%Y-%m-%d %H:%M:%OS"))
date1 - date2
Output: Time difference of 19 mins
It depends what output format you want.
For example if you want month difference between two dates, you can use the "interval" function from library "lubridate"
library(lubridate)
interval(as.Date(df$date1),as.Date(df$date2) %/% months(1))
It also works with years, weeks, days, hours
I have some MATLAB serial date number that I need to use in R but I havt to convert them to a normal date.
Matlab:
datestr(733038.6)
ans =
27-Dec-2006 14:24:00
you can see it gives the date and time.
Now we try in R:
Matlab2Rdate <- function(val) as.Date(val - 1, origin = '0000-01-01')
> Matlab2Rdate(733038.6)
[1] "2006-12-27"
It gives only the date but I need also the time? Any idea
The trick is Matlab uses "January 01, 0000", a fictional reference date, to calculate its date number. The origin of time for the "POSIXct" class in R is, ‘1970-01-01 00:00.00 UTC’. You can read about how different systems handle dates here.
Before converting, you need to account for this difference in reference from one format to another. The POSIX manual contains such an example. Here's my output:
> val<-733038.6
> as.POSIXct((val - 719529)*86400, origin = "1970-01-01", tz = "UTC")
[1] "2006-12-27 14:23:59 UTC"
Where 719529 is ‘1970-01-01 00:00.00 UTC’ in Matlab's datenum and 86400 the number of seconds in an standard UTC day.
I have a table (tags) with a column for timestamp (ts), which is formatted as seconds since 1 Jan, 1970 GMT. I'm trying to create a date column that converts the timestamp from seconds to date and time EST.
The suggested code for R was:
tags$date<-strptime(tags$ts, "%Y-%m-%d")
tags$date<-as.POSIXct(tags$date)
But when I do this, tags$date comes up as NA. Any suggestions for what I might be doing wrong? Thanks.
You should us as.POSIXct function instead:
tags$date <- as.POSIXct(tags$ts, origin="1970-01-01", tz="US/New York")
strptime converts between character representations and dates not between timestamp and dates.
Here's a lubridate version. When we use as_datetime we don't need to explicitly specify an origin as it defaults to the desired origin.
lubridate::as_datetime(1507119276, tz='EST')
# [1] "2017-10-04 07:14:36 EST"
I have a vector of decimal numbers, which represent 'decimal day', the fraction of a day. I want to convert it into HH:MM format using R.
For example, the number 0.8541667 would correspond to 20:30. How can I convert the numbers to HH:MM format?
Using chron:
chron::times(0.8541667)
#[1] 20:30:00
Try this:
R> format(as.POSIXct(Sys.Date() + 0.8541667), "%H:%M", tz="UTC")
[1] "20:30"
R>
We start with a date--which can be any date, so we use today--and add your desired fractional day.
We then convert the Date type into a Datetime object.
Finally, we format the hour and minute part of the Datetime object, ensuring that UTC is used for the timezone.
One option with data.table:
> library(data.table)
> structure(as.integer(0.4305556*60*60*24), class="ITime")
[1] "10:20:00"
We convert from day fraction to seconds since midnight; coerce to integer; and apply ITime class. (ITime works with integer-stored seconds since midnight.)
Other resources:
#GaborGrothendieck re chron package and link to his R News article with Thomas Petzoldt about converting from Excel in particular Converting a time decimal/fraction representing days to its actual time in R?
#JorisChau re RStudio's hms package how to convert excel internal coding for hours to hours in R?
I have some MATLAB serial date number that I need to use in R but I havt to convert them to a normal date.
Matlab:
datestr(733038.6)
ans =
27-Dec-2006 14:24:00
you can see it gives the date and time.
Now we try in R:
Matlab2Rdate <- function(val) as.Date(val - 1, origin = '0000-01-01')
> Matlab2Rdate(733038.6)
[1] "2006-12-27"
It gives only the date but I need also the time? Any idea
The trick is Matlab uses "January 01, 0000", a fictional reference date, to calculate its date number. The origin of time for the "POSIXct" class in R is, ‘1970-01-01 00:00.00 UTC’. You can read about how different systems handle dates here.
Before converting, you need to account for this difference in reference from one format to another. The POSIX manual contains such an example. Here's my output:
> val<-733038.6
> as.POSIXct((val - 719529)*86400, origin = "1970-01-01", tz = "UTC")
[1] "2006-12-27 14:23:59 UTC"
Where 719529 is ‘1970-01-01 00:00.00 UTC’ in Matlab's datenum and 86400 the number of seconds in an standard UTC day.