# [R] Calculating date difference in days

Boris Steipe bor|@@@te|pe @end|ng |rom utoronto@c@
Wed May 22 23:52:33 CEST 2019

```ed <- as.POSIXlt("2018-03-10")
sd <- as.POSIXlt("2018-02-10")
as.numeric(ed-sd)
[1] 28

ed <- as.POSIXlt("2000-03-10")
sd <- as.POSIXlt("2000-02-10")
as.numeric(ed-sd)
[1] 29

Cheers,
B.

> On 2019-05-22, at 17:43, reichmanj using sbcglobal.net wrote:
>
> R Help
>
> I have a function to calculate a date difference in days but my results come
> back in hours.  I suspect I am using the as.POSIXlt function incorrectly .
>
> Suggestions?
>
> # Start time of data to be considered
> start_day <- "2016-04-30"
>
> # Make event and sequence IDs into factors
> elapsed_days <- function(end_date, start_date){
>  ed <- as.POSIXlt(end_date)
>  sd <- as.POSIXlt(start_date)
>  ed-sd
> }
>
> trans_sequence\$eventID <- elapsed_days(trans_sequence\$Date, start_day)
>
>
>> trans_sequence
> # A tibble: 39 x 5
> # Groups:   Emitter [15]
>   Emitter Date        SIZE Geohash
> eventID
>     <int> <date>     <int> <chr>
> <time>
> 1       1 2016-05-01    12 A;B;C;D;E;F;G;H;I;J;K;L
> 19 hours
> 2       1 2016-05-02     5 A;B;C;D;E
> 43 hours
> 3       1 2016-05-05    11 A;B;C;D;E;F;G;H;I;J;K
> 115 hours
> 4       2 2016-05-01     9 C;D;E;F;G;H;I;J;K
> 19 hours
> 5       2 2016-05-02     3 F;G;H
> 43 hours
> 6       2 2016-05-05     3 L;M;N
> 115 hours
> 7       3 2016-05-01     3 L;M;N
> 19 hours
> 8       3 2016-05-02     3 I;J;K
> 43 hours
> 9       3 2016-05-04    25
> A;B;C;D;E;F;G;H;I;J;K;L;M;N;O;P;Q;R;S;T;U;V;W;X;Y  91 hours
> 10       3 2016-05-05     7 O;P;Q;R;S;T;U
> 115 hours
>
> Jeff Reichman
>
>
> 	[[alternative HTML version deleted]]
>
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