编写函数以引用特定列

问题描述

我必须定期但出于不同的原因从同一个 API 中提取不同的数据集，因此我必须为许多不同的提取编写代码。我想创建一些函数来帮助解决这个问题，但我需要一些帮助。

我一直无法弄清楚如何设置函数，以便我可以更改数据集，但每次仍然从同一列中提取。在这个例子中，我有 3 列的时间戳表示不同的东西（在这个数据中组成）。我需要将这里的时区更改为我的本地时区。在我的所有数据集中，列名将保持不变，但数据集的名称将发生变化。我的代码中有几个地方需要执行此操作，但我一直无法弄清楚，因此非常感谢您提供任何建议！

此示例代码的第二部分未包含在实际代码中，但用于正确设置数据。数据以 GMT 显示的格式从 API 中输出。

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)

解决方法

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