I have to pull different data sets from the same API regularly but for different reasons, so I have to write out the code for many different pulls. I'd like to create some functions to help with this, but I need some help.
I haven't been able to figure out how to set up the function so that I can change the data set but still pull from the same column each time. In this example, I have 3 columns with timestamps that mean different things (made up in this data). I need to change the timezone here to my local time zone. The column name will remain the same in all of my datasets, but the name of the dataset will change. I have a few places in my code where I need to do this, and I haven't been able to figure it out, so any suggestions would be much appreciated!
The second section of this example code is not included in the actual code, but it is there to set the data up correctly. The data comes out of the API in the format shown as GMT.
df <- data.frame(col_1 = c(1, 2, 3, 4),
time_1 = c("2021-01-20 23:58:21", "2021-01-20 21:21:00", "2021-01-20 17:14:04", "2021-01-20 01:05:18"),
time_2 = c("2021-01-19 23:58:21", "2021-01-19 21:21:00", "2021-01-19 17:14:04", "2021-01-19 01:05:18"),
time_3 = c("2021-01-18 23:46:21", "2021-01-18 36:21:00", "2021-01-18 15:14:04", "2021-01-18 01:05:18"),
time_4 = c("2021-01-17 23:58:21", "2021-01-17 20:21:00", "2021-01-17 18:14:04", "2021-01-17 02:05:18"))
# Not part of actual code
df$time_1 <- as.POSIXlt(df$time_1, tz = "GMT")
df$time_2 <- as.POSIXlt(df$time_2, tz = "GMT")
df$time_3 <- as.POSIXlt(df$time_3, tz = "GMT")
df$time_4 <- as.POSIXlt(df$time_4, tz = "GMT")
# What I want it to do
# df$time_1 <- lubridate::with_tz(df$time_1, tz = "America/Los_Angeles")
# df$time_2 <- lubridate::with_tz(df$time_2, tz = "America/Los_Angeles")
# df$time_3 <- lubridate::with_tz(df$time_3, tz = "America/Los_Angeles")
# df$time_4 <- lubridate::with_tz(df$time_4, tz = "America/Los_Angeles")
# Attempted function
timezone_cleanup <- function(my_df){
my_df$time_1 <- lubridate::with_tz(my_df$time_1, tz = "America/Los_Angeles")
my_df$time_2 <- lubridate::with_tz(my_df$time_2, tz = "America/Los_Angeles")
my_df$time_3 <- lubridate::with_tz(my_df$time_3, tz = "America/Los_Angeles")
my_df$time_4 <- lubridate::with_tz(my_df$time_4, tz = "America/Los_Angeles")
}
# how I'd like to use this function. Not working now. Even if I wrap it with data.frame(), it's not what I wanted.
new_df <- timezone_cleanup(df)
I think you need to return my_df in your function to get the changed dataframe back. However, you can use lapply or across to apply the same function to multiple columns.
library(dplyr)
timezone_cleanup <- function(my_df){
my_df %>%
mutate(across(starts_with('time'),
lubridate::with_tz, tz = "America/Los_Angeles"))
}
new_df <- timezone_cleanup(df)
By the way, I do recive a warning message while using this Unrecognized time zone 'America/Los_Angeles'. Are you sure you are using the correct tz value?