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I am trying to convert multiple columns from "character" to date, but also reformat the date. I can do it column by column, but am hoping to write some sort of loop to iterate over all the variables.

For example, I can do

dates_test$date.d.m.y <- format(as.Date(dates_test$date.d.m.y, "%d/%m/%Y), "%m/%d/%Y")

How would I write the code so that I changed the format of date.d.m.y and d.m.y.test into %m/%d/%Y format at the same time?

Dataset here:

dput(head(dates_test,20)

structure(list(date.m.d.y = c("5/13/2013", "5/14/2013", "5/15/2013", 
"5/16/2013", "5/17/2013", "5/18/2013", "5/19/2013", "5/20/2013", 
"5/21/2013", "5/22/2013", "5/23/2013", "5/24/2013", "5/25/2013", 
"5/26/2013", "5/27/2013", "5/28/2013", "5/29/2013", "5/30/2013", 
"5/31/2013", "6/1/2013"), date.d.m.y = c("2/2/2012", "2/2/2012", 
"2/2/2012", "2/2/2012", "2/2/2012", "9/2/2012", "9/2/2012", "9/2/2012", 
"9/2/2012", "9/2/2012", "16/2/2012", "16/2/2012", "16/2/2012", 
"16/2/2012", "16/2/2012", "23/2/2012", "23/2/2012", "23/2/2012", 
"23/2/2012", "23/2/2012"), date.y.m.d = c("2010-12-11", "2010-12-12", 
"2010-12-13", "2010-12-14", "2010-12-15", "2010-12-16", "2010-12-17", 
"2010-12-18", "2010-12-19", "2010-12-20", "2010-12-21", "2010-12-22", 
"2010-12-23", "2010-12-24", "2010-12-25", "2010-12-26", "2010-12-27", 
"2010-12-28", "2010-12-29", "2010-12-30"), date.d.m.y.2 = c("13.5.2013", 
"14.5.2013", "15.5.2013", "16.5.2013", "17.5.2013", "18.5.2013", 
"19.5.2013", "20.5.2013", "21.5.2013", "22.5.2013", "23.5.2013", 
"24.5.2013", "25.5.2013", "26.5.2013", "27.5.2013", "28.5.2013", 
"29.5.2013", "30.5.2013", "31.5.2013", "1.6.2013"), date.m.d.y.2 = c("13-May-2013", 
"14-May-2013", "15-May-2013", "16-May-2013", "17-May-2013", "18-May-2013", 
"19-May-2013", "20-May-2013", "21-May-2013", "22-May-2013", "23-May-2013", 
"24-May-2013", "25-May-2013", "26-May-2013", "27-May-2013", "28-May-2013", 
"29-May-2013", "30-May-2013", "31-May-2013", "1-Jun-2013"), d.m.y.test = c("2/2/2012", 
"2/2/2012", "2/2/2012", "2/2/2012", "2/2/2012", "9/2/2012", "9/2/2012", 
"9/2/2012", "9/2/2012", "9/2/2012", "16/2/2012", "16/2/2012", 
"16/2/2012", "16/2/2012", "16/2/2012", "23/2/2012", "23/2/2012", 
"23/2/2012", "23/2/2012", "23/2/2012"), new = c("13/05/2013", 
"14/05/2013", "15/05/2013", "16/05/2013", "17/05/2013", "18/05/2013", 
"19/05/2013", "20/05/2013", "21/05/2013", "22/05/2013", "23/05/2013", 
"24/05/2013", "25/05/2013", "26/05/2013", "27/05/2013", "28/05/2013", 
"29/05/2013", "30/05/2013", "31/05/2013", "01/06/2013")), row.names = c(NA, 
20L), class = "data.frame")
user16368087
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    Images are not a good way for posting data (or code). See [this Meta](https://meta.stackoverflow.com/a/285557/8245406) and a [relevant xkcd](https://xkcd.com/2116/). Can you post sample data in `dput` format? Please edit **the question** with the code you've tried and with the output of `dput(dates_test)`. Or, if it is too big with the output of `dput(head(dates_test, 20))`. – Rui Barradas Jul 02 '21 at 19:28
  • Note that when you format() you are turning the date back into a string. Is that want you want? – MrFlick Jul 02 '21 at 19:29
  • @RuiBarradas - just added the dput output. Thanks for the pro-tip and for your patience with me! – user16368087 Jul 02 '21 at 19:33
  • @MrFlick - Nope, so I guess that's problem number 2. Essentially I'm trying to get all the variables into %m/%d/%Y date format. – user16368087 Jul 02 '21 at 19:33
  • so far it seems the first column and the last columns are exactly the same. Does that mean the last column had been editted? – Onyambu Jul 02 '21 at 19:48
  • @Onyambu I just duplicated a column so I could test reformatting 2 columns at the same time. – user16368087 Jul 02 '21 at 19:52
  • but it does not seem to have a format. All the other columns have a format on their names – Onyambu Jul 02 '21 at 19:58

3 Answers3

1

We can use anydate to convert across the columns with different date formats to Date class and then apply the format to return the desired format - %m/%d/%Y

library(anytime)
library(dplyr)
addFormats("%d.%m.%Y")
dates_test1 <- dates_test %>% 
     mutate(across(everything(), ~ format(anydate(.), "%m/%d/%Y")))

-ouptut

dates_test1
 date.m.d.y date.d.m.y date.y.m.d date.d.m.y.2 date.m.d.y.2 d.m.y.test        new
1  05/13/2013 02/02/2012 12/11/2010   05/13/2013   05/13/2013 02/02/2012 05/13/2013
2  05/14/2013 02/02/2012 12/12/2010   05/14/2013   05/14/2013 02/02/2012 05/14/2013
3  05/15/2013 02/02/2012 12/13/2010   05/15/2013   05/15/2013 02/02/2012 05/15/2013
4  05/16/2013 02/02/2012 12/14/2010   05/16/2013   05/16/2013 02/02/2012 05/16/2013
5  05/17/2013 02/02/2012 12/15/2010   05/17/2013   05/17/2013 02/02/2012 05/17/2013
6  05/18/2013 09/02/2012 12/16/2010   05/18/2013   05/18/2013 09/02/2012 05/18/2013
7  05/19/2013 09/02/2012 12/17/2010   05/19/2013   05/19/2013 09/02/2012 05/19/2013
8  05/20/2013 09/02/2012 12/18/2010   05/20/2013   05/20/2013 09/02/2012 05/20/2013
9  05/21/2013 09/02/2012 12/19/2010   05/21/2013   05/21/2013 09/02/2012 05/21/2013
10 05/22/2013 09/02/2012 12/20/2010   05/22/2013   05/22/2013 09/02/2012 05/22/2013
11 05/23/2013 02/16/2012 12/21/2010   05/23/2013   05/23/2013 02/16/2012 05/23/2013
12 05/24/2013 02/16/2012 12/22/2010   05/24/2013   05/24/2013 02/16/2012 05/24/2013
13 05/25/2013 02/16/2012 12/23/2010   05/25/2013   05/25/2013 02/16/2012 05/25/2013
14 05/26/2013 02/16/2012 12/24/2010   05/26/2013   05/26/2013 02/16/2012 05/26/2013
15 05/27/2013 02/16/2012 12/25/2010   05/27/2013   05/27/2013 02/16/2012 05/27/2013
16 05/28/2013 02/23/2012 12/26/2010   05/28/2013   05/28/2013 02/23/2012 05/28/2013
17 05/29/2013 02/23/2012 12/27/2010   05/29/2013   05/29/2013 02/23/2012 05/29/2013
18 05/30/2013 02/23/2012 12/28/2010   05/30/2013   05/30/2013 02/23/2012 05/30/2013
19 05/31/2013 02/23/2012 12/29/2010   05/31/2013   05/31/2013 02/23/2012 05/31/2013
20 06/01/2013 02/23/2012 12/30/2010   01/06/2013   06/01/2013 02/23/2012 06/01/2013
akrun
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1

Here is a way with package lubridate function parse_date_time. The main trick is to first get the formats from the column names.

library(lubridate)

fmt <- names(dates_test)
fmt <- sub("date", "", fmt)
fmt <- unique(gsub("[^dmy]", "", fmt))
fmt <- fmt[nchar(fmt) == 3]

dates_new <- lapply(dates_test, parse_date_time, orders = fmt)
dates_new <- do.call(cbind.data.frame, dates_new)

str(dates_new)
#'data.frame':  20 obs. of  7 variables:
# $ date.m.d.y  : POSIXct, format: "2013-05-13" ...
# $ date.d.m.y  : POSIXct, format: "2012-02-02" ...
# $ date.y.m.d  : POSIXct, format: "2010-12-11" ...
# $ date.d.m.y.2: POSIXct, format: "2013-05-13" ...
# $ date.m.d.y.2: POSIXct, format: "2013-05-13" ...
# $ d.m.y.test  : POSIXct, format: "2012-02-02" ...
# $ new         : POSIXct, format: "2013-05-13" ...

Now that the columns are all of class "POSIXct", lapply the appropriate format method. R's S3 classes mechanism will automatically call it.

dates_new[] <- lapply(dates_new, format, format = "%m/%d/%Y")
str(dates_new)
#'data.frame':  20 obs. of  7 variables:
# $ date.m.d.y  : chr  "05/13/2013" "05/14/2013" "05/15/2013" "05/16/2013" ...
# $ date.d.m.y  : chr  "02/02/2012" "02/02/2012" "02/02/2012" "02/02/2012" ...
# $ date.y.m.d  : chr  "12/11/2010" "12/12/2010" "12/13/2010" "12/14/2010" ...
# $ date.d.m.y.2: chr  "05/13/2013" "05/14/2013" "05/15/2013" "05/16/2013" ...
# $ date.m.d.y.2: chr  "05/13/2013" "05/14/2013" "05/15/2013" "05/16/2013" ...
# $ d.m.y.test  : chr  "02/02/2012" "02/02/2012" "02/02/2012" "02/02/2012" ...
# $ new         : chr  "05/13/2013" "05/14/2013" "05/15/2013" "05/16/2013" ...
Rui Barradas
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0

You can use the parsedate package and format the output as required.

library(parsedate)

for (i in colnames(dates_test)) {
  dates_test[,i] <- format(parse_date(dates_test[,i]),"%m/%d/%Y")
}

dates_test
   date.m.d.y date.d.m.y date.y.m.d date.d.m.y.2 date.m.d.y.2 d.m.y.test        new
1  05/13/2013 02/02/2012 12/11/2010   05/13/2013   05/13/2013 02/02/2012 05/13/2013
2  05/14/2013 02/02/2012 12/12/2010   05/14/2013   05/14/2013 02/02/2012 05/14/2013
3  05/15/2013 02/02/2012 12/13/2010   05/15/2013   05/15/2013 02/02/2012 05/15/2013
4  05/16/2013 02/02/2012 12/14/2010   05/16/2013   05/16/2013 02/02/2012 05/16/2013
5  05/17/2013 02/02/2012 12/15/2010   05/17/2013   05/17/2013 02/02/2012 05/17/2013
6  05/18/2013 09/02/2012 12/16/2010   05/18/2013   05/18/2013 09/02/2012 05/18/2013
7  05/19/2013 09/02/2012 12/17/2010   05/19/2013   05/19/2013 09/02/2012 05/19/2013
8  05/20/2013 09/02/2012 12/18/2010   05/20/2013   05/20/2013 09/02/2012 05/20/2013
9  05/21/2013 09/02/2012 12/19/2010   05/21/2013   05/21/2013 09/02/2012 05/21/2013
10 05/22/2013 09/02/2012 12/20/2010   05/22/2013   05/22/2013 09/02/2012 05/22/2013
11 05/23/2013 02/16/2012 12/21/2010   05/23/2013   05/23/2013 02/16/2012 05/23/2013
12 05/24/2013 02/16/2012 12/22/2010   05/24/2013   05/24/2013 02/16/2012 05/24/2013
13 05/25/2013 02/16/2012 12/23/2010   05/25/2013   05/25/2013 02/16/2012 05/25/2013
14 05/26/2013 02/16/2012 12/24/2010   05/26/2013   05/26/2013 02/16/2012 05/26/2013
15 05/27/2013 02/16/2012 12/25/2010   05/27/2013   05/27/2013 02/16/2012 05/27/2013
16 05/28/2013 02/23/2012 12/26/2010   05/28/2013   05/28/2013 02/23/2012 05/28/2013
17 05/29/2013 02/23/2012 12/27/2010   05/29/2013   05/29/2013 02/23/2012 05/29/2013
18 05/30/2013 02/23/2012 12/28/2010   05/30/2013   05/30/2013 02/23/2012 05/30/2013
19 05/31/2013 02/23/2012 12/29/2010   05/31/2013   05/31/2013 02/23/2012 05/31/2013
20 06/01/2013 02/23/2012 12/30/2010   06/01/2013   06/01/2013 02/23/2012 01/06/2013
Mohanasundaram
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