Question

我在df列中有一堆日期，格式如下：dd.mm.yyyy

我希望它看起来像这样：01/2020（mm.yyyy）

如何从所有日期中删除日期？

Answer 1

使用format指定所需的日期格式

date <- as.Date("13/01/2020", format = "%d/%m/%Y")
format(date, "%m/%Y")
[1] "01/2020"

编辑-应用于数据框列

dates <- c("13/01/2020", "17/02/2015", "13/03/2013")
df <- data.frame(dates, stringsAsFactors = FALSE)
df$dates <- as.Date(df$dates, format = "%d/%m/%Y")
df$dates_format <- format(df$dates, "%m/%Y")
df
       dates dates_format
1 2020-01-13      01/2020
2 2015-02-17      02/2015
3 2013-03-13      03/2013

Answer 2

除了@Greg的format之外，另一个选择是使用sub如下

> sub(".*?/","","13/01/2020")
[1] "01/2020"

Answer 3

R中有明确的日期格式选项（请参阅Greg的答案）。另一种选择是将日期分成三列，然后重新组合月份和年份，并在其之间插入一个/。请注意，这会将新日期列保留为字符格式，您可能需要根据需要进行更改。

library(tidyr)
df <- data.frame(date = "13/01/2020")
df <- separate(df, date, into = c("day","month","year"), sep = "/")
df$newdate <- paste(df$month, df$year, sep = "/")

Answer 4

这是使用lubridate的解决方案。

library(lubridate)

#Set the desired format (mm-yyyy) as my_stamp
my_stamp<-stamp( "02-2019", 
                 orders = "my") 

#A df with a column full of dates
df <- data.frame(dates = c("30/04/2020","29/03/2020","28/02/2020"))

#Change the column from string to date format
df$dates<-dmy(df$dates)

#Apply the format you desire to the dates (i.e., only month and year)
df$dates<-my_stamp(df$dates)

#    dates
#1 04-2020
#2 03-2020
#3 02-2020

R：如何从日期中删除日期？

4 个答案: