如何更改同一列中的多种日期格式? [英] How to change multiple Date formats in same column?

问题描述

到目前为止，我得到的是一个数据框列，其中包含不同字符格式的日期.一些出现在 %d.%m.%Y 模式中，一些出现在 %m/%d/%Y 中:

What I've got so far is a dataframe column with dates in different character formats. A few appear in the %d.%m.%Y pattern, some in %m/%d/%Y :

data$initialDiagnose = as.character(data$initialDiagnose)
data$initialDiagnose[1:10]

[1] "14.01.2009" "9/22/2005"  "4/21/2010" "28.01.2010" "09.01.2009" "3/28/2005" "04.01.2005" "04.01.2005" "9/17/2010" "03.01.2010"

我希望它们是一种格式的 Date()，但 R 拒绝了.
所以我首先尝试通过分隔符来改变它们:

I want them as Date() in one format, but R refuses of course.
So I tried at first to change them by the separator:

data$initialDiagnose[grep('/', data$initialDiagnose)] = as.character.Date(data$initialDiagnose[grep('/', data$initialDiagnose)], format = '%m/%d/%Y')

模拟."日期.但是没有用.

Analog to the '.' dates. But it didn't work.

如何将它们全部更改为一种格式，以便我可以使用它们?

How can I change them all to one format, that I can work with them?

推荐答案

我喜欢 lubridate，因为它易于使用:

I like lubridate for its ease of use:

library(lubridate) 

# note added ugly formats below
data <- data.frame(initialDiagnose = c("14.01.2009", "9/22/2005", 
        "4/21/2010", "28.01.2010", "09.01.2009", "3/28/2005", 
        "04.01.2005", "04.01.2005", "Created on 9/17/2010", "03 01 2010"))

mdy <- mdy(data$initialDiagnose) 
dmy <- dmy(data$initialDiagnose) 
mdy[is.na(mdy)] <- dmy[is.na(mdy)] # some dates are ambiguous, here we give 
data$initialDiagnose <- mdy        # mdy precedence over dmy
data
#   initialDiagnose
#       2009-01-14
#       2005-09-22
#       2010-04-21
#       2010-01-28
#       2009-09-01
#       2005-03-28
#       2005-04-01
#       2005-04-01
#       2010-09-17
#       2010-03-01

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