ggplot2-datetime-timezone-plotting.R

library(lubridate)
library(tidyverse)

seq(
    from=as.POSIXct("2012-1-1 0:00", tz="UTC"),
    to=as.POSIXct("2012-1-3 23:00", tz="UTC"),
    by="hour"
) ->
    dt

tibble(
    dt_utc = dt,
    dt_ny = with_tz(dt, tzone = "America/New_York"),
    dt_la = with_tz(dt, tzone = "America/Los_Angeles"),
    val = sin(2 * pi * as.numeric(dt) / 86400)) ->
    df_work

## UTC x-axis
## Labeled timestamps indeed agree with UTC
ggplot(data=df_work) +
    geom_line(mapping=aes(x=dt_utc, y=val)) +
    scale_x_datetime(breaks = "1 hour") +
    theme(
        axis.text.x = element_text(angle = 90)
    ) +
    labs(
        title="UTC Time"
    )


## Pacific times
## Indeed, x-axis labels are in America/Los_Angeles
ggplot(data=df_work) +
    geom_line(mapping=aes(x=dt_la, y=val)) +
    scale_x_datetime(breaks = "1 hour") +
    theme(
        axis.text.x = element_text(angle = 90)
    ) +
    labs(
        title="America/Los_Angeles Time"
    )


## UTC, but America/Los_Angeles supplied to scale_x_datetime
## No, labels are again in UTC.  Doesn't behave as I expect.
## I think this is rather a 'force_tz' rather than `with_tz'.
ggplot(data=df_work) +
    geom_line(mapping=aes(x=dt_utc, y=val)) +
    scale_x_datetime(breaks = "1 hour", timezone = "America/Los_Angeles") +
    theme(
        axis.text.x = element_text(angle = 90)
    ) +
    labs(
        title="Original timestamp in UTC, scale_x_datetime timezone arg is America/Los_Angeles Time"
    )




## UTC, but America/Los_Angeles supplied to scale_x_datetime
## Added explicit `date_labels` argument.
## Now it works.
## See: https://github.com/tidyverse/ggplot2/issues/4007
ggplot(data=df_work) +
    geom_line(mapping=aes(x=dt_utc, y=val)) +
    scale_x_datetime(breaks = "1 hour", timezone = "America/Los_Angeles", date_labels = "%F %T") +
    theme(
        axis.text.x = element_text(angle = 90)
    ) +
    labs(
        title="Original timestamp in UTC, scale_x_datetime timezone arg is America/Los_Angeles Time"
    )