如何将 R 数据帧中的时间戳转换为日期

Question

I have a R data frame with multiple columns with one of which containing a timestamp.

df <- data.frame(id=c(1:4), timestamp=c(123513,2,3,4))

The problem I have is trying to convert the timestamp say 123513 (integer) into a date ("1970-01-02").

I have a function as below, that I wish to apply to all timestamps.

timestamp_to_date <- function(timestamp) {
    return (as.Date(as.POSIXct(timestamp, origin="1970-01-01", tz="Australia/Melbourne")))
}

Answer 1

As the other have mentioned, this should just work:

df <- data.frame(id=c(1:4), timestamp=c(123513,2,3,4))

timestamp_to_date <- function(timestamp) {
  return (as.Date(as.POSIXct(timestamp, origin="1970-01-01", tz="Australia/Melbourne")))
}

df$timestamp = timestamp_to_date(df$timestamp)

> df
  id  timestamp
1  1 1970-01-02
2  2 1970-01-01
3  3 1970-01-01
4  4 1970-01-01