CODEWITHSUNDEEP
r
Freda K
Freda K

Reputation: 464

Preallocating a dataframe in R with date as the column class

I want to preallocate space for dates in an R dataframe.

To preallocate space for characters and numbers, I would write

MyDataframe <- data.frame(Name = character(10), 
                          Tickets  = numeric(10))

What would I add next to preallocate space for dates? This does not work...

# DOES NOT WORK
MyDataframe <- data.frame(Name = character(10), 
                          Tickets  = numeric(10)
                          Date = Date(10))

Currently, I define the column as numeric, then coerce to dates, but this seems less than ideal.
Thanks

Upvotes: 4

Views: 11121

Answers (2)

Freda K
Freda K

Reputation: 464

Here is my final code. It works well. 

MyDF <- data.frame(Name = character(10),
                   Tickets = numeric(10),
                   Date = as.Date(rep(0,10), origin = "1900-01-01"))

Here is the output:

> MyDF

   Name Tickets       Date
1             0 1900-01-01
2             0 1900-01-01
3             0 1900-01-01
4             0 1900-01-01
5             0 1900-01-01
6             0 1900-01-01
7             0 1900-01-01
8             0 1900-01-01
9             0 1900-01-01
10            0 1900-01-01

And the summary

> summary(MyDF)

 Name     Tickets       Date           
 :10   Min.   :0   Min.   :1900-01-01  
       1st Qu.:0   1st Qu.:1900-01-01  
       Median :0   Median :1900-01-01  
       Mean   :0   Mean   :1900-01-01  
       3rd Qu.:0   3rd Qu.:1900-01-01  
       Max.   :0   Max.   :1900-01-01

Thanks for your help

Upvotes: 1

Andy
Andy

Reputation: 4659

If all you are looking for is a placeholder column with 10 dates, this works:

as.Date(1:10, origin=Sys.Date())

Your problem is that the character() and numeric() functions take a length argument, but as.Date (as there is no Date() function) does not (?as.Date)

Upvotes: 5

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