s-u/fasttime

Fast utility for date/time parsing and conversion in R

fasttime's Issues

fasttime not returning correct date from character in R

fasttime does not correctly return dates.
'''library(data.table)
library(fasttime)
dt<-data.table(Time=c("29/12/2022 12:13:51"
,"29/12/2022 12:13:52"
,"29/12/2022 12:13:53"
,"29/12/2022 12:13:54"
,"29/12/2022 12:13:56"
,"30/12/2022 6:29:11"
,"30/12/2022 6:29:12"
,"30/12/2022 6:29:13"
,"30/12/2022 6:29:14"
,"30/12/2022 6:29:15"))

fastPOSIXct(dt$Time,"GMT",required.components = 6L)
[1] "2035-06-14 12:13:51 GMT" "2035-06-14 12:13:52 GMT" "2035-06-14 12:13:53 GMT"
[4] "2035-06-14 12:13:54 GMT" "2035-06-14 12:13:56 GMT" "2036-06-13 06:29:11 GMT"
[7] "2036-06-13 06:29:12 GMT" "2036-06-13 06:29:13 GMT" "2036-06-13 06:29:14 GMT"
[10] "2036-06-13 06:29:15 GMT"
fastPOSIXct(dt$Time)
[1] "2035-06-14 15:13:51 IDT" "2035-06-14 15:13:52 IDT" "2035-06-14 15:13:53 IDT"
[4] "2035-06-14 15:13:54 IDT" "2035-06-14 15:13:56 IDT" "2036-06-13 09:29:11 IDT"
[7] "2036-06-13 09:29:12 IDT" "2036-06-13 09:29:13 IDT" "2036-06-13 09:29:14 IDT"
[10] "2036-06-13 09:29:15 IDT"
'''

[feature request] fastDate()

Just a suggestion, I think a fastDate function would be worthwhile. This:

fastDate <- function(x) as.Date( fasttime::fastPOSIXct( x, "UTC", 3L ) )

Is around 60x faster than both as.Date and lubridate::as_date, and produces identical results. Just a simple wrapper, but I'm finding myself using it a lot, so thought others might find it useful too. I'd be happy to make a pull request if you like the idea.

# test data
dates <- as.Date( seq.int( 1, to = 1E4, by = 1 ), origin = "1970-01-01" )
x <- as.character( dates )

res <- microbenchmark::microbenchmark(
    fast = { fast <- fastDate( x ) },
    lubr = { lubr <- lubridate::as_date( x ) },
    base = { base <- as.Date( x ) },
    times = 10
)
setDT(res)[ , .( median = signif( median( time ) / 1E6, 4 ) ), by = expr ]

#        expr    median
# 1:    lubr     61.020
# 2:    base     60.520
# 3:    fast      1.054

identical( dates, fast ) # TRUE
identical( dates, lubr ) # TRUE
identical( dates, base ) # TRUE

BTW, fantastic package, I'm blown away every time I run a benchmark.

Push most recent version to CRAN

Hello, @s-u. Any reason the most recent version here and on r-forge has not been pushed to CRAN?

fastPOSIXct fails to convert seconds with decimals

I have to process a very large (several millions rows) timeseries with a 0.1 sec interval.
After importing a file using fread() timestamps are correctly stored as strings:

"2018-08-29 12:45:00.6"
"2018-08-29 12:45:00.7"
"2018-08-29 12:45:00.8"
"2018-08-29 12:45:00.9"
"2018-08-29 12:45:01"
"2018-08-29 12:45:01.1"
"2018-08-29 12:45:01.2"

Then I tried to convert them to posixct using:
dati1$TIMESTAMP = fastPOSIXct(dati1$TIMESTAMP, tz = "UTC", required.components = 6L)

But looks like something goes wrong, the function still returns decimals of seconds but they look somehow rounded like this:

2018-08-29 12:45:00.5
2018-08-29 12:45:00.7
2018-08-29 12:45:00.7
2018-08-29 12:45:00.9
2018-08-29 12:45:01.0
2018-08-29 12:45:01.0
2018-08-29 12:45:01.2
2018-08-29 12:45:01.2

Is that a limit of fasttime or a bug?

Thanks

parsing "20160930 12:03:04.567"

Hi Simon,
I'd like to suggest a small enchancement: whenever four digits have been "collected", call it a year and move on to month, regardless if a separator is present or not. Same between months and days but with two digits. Maybe a new parameter require.separators=true makes sense, for rare cases where y,m,d are represented by more than 4,2,2 digits respectively.

Add fastDate

Not sure this is the place for a feature request (nor if it is done) but it would be very nice to get a fastDate function that would cast Character to Date. Looking at tparse.c it might just be cuting some part off ?
fastDate('2011-01-01') or fastDate('20110304') would give [1] Date '2011-01-01'

Incorrect result from fastPOSIXct

Starting from 2039, the parsed result become incorrect

> fastPOSIXct('2039-12-31', 'GMT')
[1] "1903-11-24 17:31:44 GMT"