R - Problem在数据框中存储润滑日期

Question

当我试图在DF中存储日期时，它被表示为数字而不是数据格式。下面是我的例子。

library(lubridate)
df1 = data.frame(task = c('do somthing', 'do something else', 'do something more')
,Start_date = c(NA, NA, NA))
Start_date = ymd("2023-12-01")
df1$Date_Start[1] = Start_date
Start_date     #this returns a "2023-12-01"
df1$Date_Start[1]  #this returns a 19692

我想让df1$Date_Start[1]存储"2023-12-01">

Answer 1

这与lubridate无关，因为您将在as.Date中获得与lubridate::ymd相同的结果。

当您创建一个NA值的列，但您计划将日期写入其中时，您需要告诉R您打算通过使用as.Date(NA)填充该列来将其用于日期。否则，R会将日期转换为数值。

library(lubridate)
df1 = data.frame(task = c('do somthing', 'do something else', 'do something more')
,Date_Start = c(NA, NA, NA))
Start_date = ymd("2023-12-01")
df1$Date_Start <- as.Date(NA)
df1$Date_Start[1] <- Start_date[1]
Start_date 
#> [1] "2023-12-01"
df1$Date_Start[1] 
#> [1] "2023-12-01"
df1
#>                task Date_Start
#> 1       do somthing 2023-12-01
#> 2 do something else       <NA>
#> 3 do something more       <NA>

^{创建于2022-12-29与reprex v2.0.2}

Answer 2

Start_date变量被创建为逻辑对象:

str(df1)
'data.frame':   3 obs. of  2 variables:
$ task      : chr  "do somthing" "do something else" "do something more"
$ Start_date: logi  NA NA NA

在第一个元素定义日期后，对象被转换为数字

str(df1)
'data.frame':   3 obs. of  2 variables:
$ task      : chr  "do somthing" "do something else" "do something more"
$ Start_date: num  19692 NA NA

您可以通过将Start_date变量的类型定义为Date对象来创建data.frame。

df1 = data.frame(task = c('do somthing', 'do something else', 'do something more'), Start_date = as.Date(NA))
str(df1)
'data.frame':   3 obs. of  2 variables:
$ task      : chr  "do somthing" "do something else" "do something more"
$ Start_date: Date, format: NA NA NA

现在可以在第一个元素中定义日期:

df1$Start_date[1] = Start_date
df1
task Start_date
1       do somthing 2023-12-01
2 do something else       <NA>
3 do something more       <NA>

Answer 3

您可以直接指定您的日期格式:

library(lubridate)
df1 = data.frame(task = c('do somthing', 'do something else', 'do something more')
,Start_date = c(NA, NA, NA))
df1$Start_date[1] <- format(ymd("2023-12-01"), "%Y-%m-%d")