user3006691 user3006691 - 2 months ago 25
R Question

Convert Unix timestamp into datetime in R

I have the following data frame

> head(try)
creates time
1 128.29508 1417392072
3 236.98361 1417392072
7 98.45902 1417392072
9 157.44068 1417392131
10 227.38333 1417392131
11 242.03390 1417392131

> str(try)
'data.frame': 102968 obs. of 2 variables:
$ creates: num 128.3 237 98.5 157.4 227.4 ...
$ time : Factor w/ 26418 levels "1417392071","1417392072",..: 2 2 2 3 3 3 3 3 5 5 ...


I am unable to convert the UNIX timestamp into datetime using the following methods I tried

> head(as.POSIXlt(as.numeric(try$time),origin="1970-01-01",tz="GMT"))
[1] "1970-01-01 00:00:02 UTC" "1970-01-01 00:00:02 UTC" "1970-01-01 00:00:02 UTC" "1970-01-01 00:00:03 UTC" "1970-01-01 00:00:03 UTC"
[6] "1970-01-01 00:00:03 UTC"

> head(as.POSIXct(as.character(try$time),tz="GMT"))
Error in as.POSIXlt.character(x, tz, ...) :
character string is not in a standard unambiguous format

> head(as.POSIXlt(as.POSIXct(as.vector(as.numeric(try$time)),origin="1970-01-01")))
[1] "1970-01-01 00:00:02 UTC" "1970-01-01 00:00:02 UTC" "1970-01-01 00:00:02 UTC" "1970-01-01 00:00:03 UTC" "1970-01-01 00:00:03 UTC"
[6] "1970-01-01 00:00:03 UTC"


I'm not sure what I'm doing incorrectly here

Answer

You have to convert from Factor to Character To Number before using as.POSIXct. The function is expecting an integer as a Unixtime

head(as.POSIXct(as.numeric(as.character(try$time)),origin="1970-01-01",tz="GMT"))
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