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Patrick Casimir

2017-Aug-22 18:30 UTC

[R] Convert Factor to Date

Dear R Fellows,


I Have a dataset( data1) with 2 columns of date showing a class of factor. How
to convert them to date? Then compare them, keep the greater date only in a new
column. Using as.Date to change the class to Date but the data becomes NA.


Much Thanks


COL1    COL2
Apr-16  1-Nov-16
May-16  1-Nov-16
Jun-16  1-Nov-16
Jul-16  1-Nov-16
Aug-16  1-Nov-16
Sep-16  1-Nov-16
Oct-16  1-Nov-16
Nov-16  1-Nov-16
Dec-16  1-Nov-16
Jan-17  1-Nov-16
Feb-17  1-Nov-16
Mar-17  1-Nov-16
Apr-17  1-Nov-16
May-17  1-Nov-16
Jun-17  1-Nov-16
Jul-17  1-Nov-16
Aug-17  1-Nov-16
Sep-17  1-Nov-16


	[[alternative HTML version deleted]]

Spencer Graves

2017-Aug-22 18:49 UTC

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[R] Convert Factor to Date

On 2017-08-22 1:30 PM, Patrick Casimir wrote:> Dear R Fellows,
>
>
> I Have a dataset( data1) with 2 columns of date showing a class of factor.
How to convert them to date? Then compare them, keep the greater date only in a
new column. Using as.Date to change the class to Date but the data becomes NA.

 ????? When I specified a format with the second date, I got the desired 
behavior:


 > as.Date(factor('1-Nov-16'), '%d-%b-%y')
[1] "2016-11-01"
 > as.Date('Nov-16', '%b-%y')
[1] NA
 > as.Date(factor('Nov-16'), '%b-%y')
[1] NA
 > as.Date('Nov-16', '%b-%y')
[1] NA


 ????? To convert the first column, I pasted "1-" in front:


as.Date(paste0('1-', factor('Nov-16')), '%d-%b-%y')


 ????? Hope this helps.? Spencer
> Much Thanks
>
>
> COL1    COL2
> Apr-16  1-Nov-16
> May-16  1-Nov-16
> Jun-16  1-Nov-16
> Jul-16  1-Nov-16
> Aug-16  1-Nov-16
> Sep-16  1-Nov-16
> Oct-16  1-Nov-16
> Nov-16  1-Nov-16
> Dec-16  1-Nov-16
> Jan-17  1-Nov-16
> Feb-17  1-Nov-16
> Mar-17  1-Nov-16
> Apr-17  1-Nov-16
> May-17  1-Nov-16
> Jun-17  1-Nov-16
> Jul-17  1-Nov-16
> Aug-17  1-Nov-16
> Sep-17  1-Nov-16
>
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

Patrick Casimir

2017-Aug-22 19:04 UTC

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[R] Convert Factor to Date

This is large data set Spencer. What about when the dates change as below:


COL1    COL2
Jan-14  1-Aug-16
Feb-14  1-Aug-16
Mar-14  1-Aug-16
Apr-14  1-Aug-16
May-14  1-Aug-16
Jun-14  1-Aug-16
Jul-14  1-Aug-16
Aug-14  1-Aug-16
Sep-14  1-Aug-16
Oct-14  1-Aug-16
Nov-14  1-Aug-16
Dec-14  1-Aug-16
Jan-15  1-Aug-16
Feb-15  1-Aug-16
Mar-15  1-Aug-16
Apr-15  1-Aug-16
May-15  1-Aug-16
Jun-15  1-Aug-16
Jul-15  1-Aug-16
Aug-15  1-Aug-16
Sep-15  1-Aug-16
Oct-15  1-Aug-16
Nov-15  1-Aug-16
Dec-15  1-Aug-16
Jan-16  1-Aug-16
Feb-16  1-Aug-16
Mar-16  1-Aug-16
Apr-16  1-Aug-16
May-16  1-Aug-16
Jun-16  1-Aug-16
Jul-16  1-Aug-16
Aug-16  1-Aug-16
Sep-16  1-Aug-16
Oct-16  1-Aug-16






________________________________
From: R-help <r-help-bounces at r-project.org> on behalf of Spencer Graves
<spencer.graves at effectivedefense.org>
Sent: Tuesday, August 22, 2017 2:49 PM
To: r-help at r-project.org
Subject: Re: [R] Convert Factor to Date



On 2017-08-22 1:30 PM, Patrick Casimir wrote:> Dear R Fellows,
>
>
> I Have a dataset( data1) with 2 columns of date showing a class of factor.
How to convert them to date? Then compare them, keep the greater date only in a
new column. Using as.Date to change the class to Date but the data becomes NA.

       When I specified a format with the second date, I got the desired
behavior:


 > as.Date(factor('1-Nov-16'), '%d-%b-%y')
[1] "2016-11-01"
 > as.Date('Nov-16', '%b-%y')
[1] NA
 > as.Date(factor('Nov-16'), '%b-%y')
[1] NA
 > as.Date('Nov-16', '%b-%y')
[1] NA


       To convert the first column, I pasted "1-" in front:


as.Date(paste0('1-', factor('Nov-16')), '%d-%b-%y')


       Hope this helps.  Spencer
> Much Thanks
>
>
> COL1    COL2
> Apr-16  1-Nov-16
> May-16  1-Nov-16
> Jun-16  1-Nov-16
> Jul-16  1-Nov-16
> Aug-16  1-Nov-16
> Sep-16  1-Nov-16
> Oct-16  1-Nov-16
> Nov-16  1-Nov-16
> Dec-16  1-Nov-16
> Jan-17  1-Nov-16
> Feb-17  1-Nov-16
> Mar-17  1-Nov-16
> Apr-17  1-Nov-16
> May-17  1-Nov-16
> Jun-17  1-Nov-16
> Jul-17  1-Nov-16
> Aug-17  1-Nov-16
> Sep-17  1-Nov-16
>
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
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>
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> and provide commented, minimal, self-contained, reproducible code.
______________________________________________
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PLEASE do read the posting guide
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and provide commented, minimal, self-contained, reproducible code.

	[[alternative HTML version deleted]]

Patrick Casimir

2017-Aug-23 14:53 UTC

head link

[R] Comparing 2 dale columns

Dear R fellows,


I created a new column Date_flag to compare the dates of COL1 and COL2 using the
code
below. But it showed that 5/1/15 is greater than 6/1/2014 and 5/1/2015 greater
than
7/1/2014 despite the year is greater. How do I fix that? I did try to format as
%y/%m/%d

 but it does not fix that.


data$Date_Flag <- ifelse(data$COL2 > data$COL1, 0,1)


COL1       COL2
6/1/14     5/1/15
7/1/14     5/1/15


data$COL2<- as.Date(as.character(data$COL2, format="%y/%m/%d"))
data$COL1<- as.Date(as.character(data$COL1, format="%y/%m/%d"))


	[[alternative HTML version deleted]]

PIKAL Petr

2017-Aug-23 15:20 UTC

head link

[R] Comparing 2 dale columns

Hi

your code is wrong.

I get> test<-read.table("clipboard", header=T)
> str(test)'data.frame':   2 obs. of  2 variables:
 $ COL1: Factor w/ 2 levels "6/1/14","7/1/14": 1 2
 $ COL2: Factor w/ 1 level "5/1/15": 1 1> test$COL2<- as.Date(as.character(test$COL2,
format="%y/%m/%d"))
> test$COL1<- as.Date(as.character(test$COL1,
format="%y/%m/%d"))                                                                                
^^^^^^^^^^^^^^^^^^^^^^^
incorrect parentheses position, wrong y,m,d

Using correct syntax I get correct result.
> test$COL2<- as.Date(test$COL2, format="%d/%m/%y")
> test$COL1<- as.Date(test$COL1, format="%d/%m/%y")
>
> test$COL2 > test$COL1
[1] TRUE TRUE> test        COL1       COL2
1 2014-01-06 2015-01-05
2 2014-01-07 2015-01-05>
Cheers
Petr
> -----Original Message-----
> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Patrick
> Casimir
> Sent: Wednesday, August 23, 2017 4:54 PM
> To: r-help at r-project.org
> Subject: [R] Comparing 2 dale columns
>
> Dear R fellows,
>
>
> I created a new column Date_flag to compare the dates of COL1 and COL2
> using the code below. But it showed that 5/1/15 is greater than 6/1/2014
and
> 5/1/2015 greater than
> 7/1/2014 despite the year is greater. How do I fix that? I did try to
format as
> %y/%m/%d
>
>  but it does not fix that.
>
>
> data$Date_Flag <- ifelse(data$COL2 > data$COL1, 0,1)
>
>
> COL1       COL2
> 6/1/14     5/1/15
> 7/1/14     5/1/15
>
>
> data$COL2<- as.Date(as.character(data$COL2,
format="%y/%m/%d"))
> data$COL1<- as.Date(as.character(data$COL1,
format="%y/%m/%d"))
>
>
>       [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
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Mark Sharp

2017-Aug-23 15:28 UTC

head link

[R] Comparing 2 dale columns

Patrick,

## Run the following script an notice the different values of the dataframe
"data" in each instance.

# I understand you have done something like the following:
data <- data.frame(COL1 = c("6/1/14", "7/1/14"),
                   COL2 = c("5/1/15", "5/1/15"),
stringsAsFactors = FALSE)
data$Date_Flag <- ifelse(data$COL2 > data$COL1, 0,1)
data
data$COL2 <- as.Date(as.character(data$COL2, format = "%y/%m/%d"))
data$COL1 <- as.Date(as.character(data$COL1, format = "%y/%m/%d"))
data$Date_Flag <- ifelse(data$COL2 > data$COL1, 0,1)
data

# What you may want instead is the following:
data <- data.frame(COL1 = c("6/1/14", "7/1/14"),
                   COL2 = c("5/1/15", "5/1/15"),
stringsAsFactors = FALSE)
data
## strptime() converts the character vector to POSIXct so you do not necessarily
## need the as.Date. However, they are not the same and you may need the Date
## class.
data$COL2 <- as.Date(strptime(data$COL2, format = "%m/%d/%y"))
data$COL1 <- as.Date(strptime(data$COL1, format = "%m/%d/%y"))
data
data$Date_Flag <- ifelse(data$COL2 > data$COL1, 0,1)
data


R. Mark Sharp, Ph.D.
msharp at TxBiomed.org




> On Aug 23, 2017, at 9:53 AM, Patrick Casimir <patrcasi at nova.edu>
wrote:
>
> data$Date_Flag <- ifelse(data$COL2 > data$COL1, 0,1)
>
>
> COL1       COL2
> 6/1/14     5/1/15
> 7/1/14     5/1/15
>
>
> data$COL2<- as.Date(as.character(data$COL2,
format="%y/%m/%d"))
> data$COL1<- as.Date(as.character(data$COL1,
format="%y/%m/%d"))
>
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