Specify custom Date format for colClasses argument in read.table/read.csv

You can write your own function that accepts a string and converts it to a Date using the format you want, then use the setAs to set it as an as method. Then you can use your function as part of the colClasses.

Try:

setAs("character","myDate", function(from) as.Date(from, format="%d/%m/%Y") )tmp <- c("1, 15/08/2008", "2, 23/05/2010")con <- textConnection(tmp)tmp2 <- read.csv(con, colClasses=c('numeric','myDate'), header=FALSE)str(tmp2)

Then modify if needed to work for your data.

Edit ---

You might want to run setClass('myDate') first to avoid the warning (you can ignore the warning, but it can get annoying if you do this a lot and this is a simple call that gets rid of it).

If there is only 1 date format you want to change, you could use the Defaults package to change the default format within as.Date.character

library(Defaults)setDefaults('as.Date.character', format = '%d/%M/%Y')dataImport <- read.csv("data.csv", colClasses = c("factor","factor","Date"))str(dataImport)## 'data.frame':    10 obs. of  3 variables:##  $ func_loc     : Factor w/ 5 levels "3076WAG0003",..: 1 2 3 3 3 3 3 4 4 5##  $ order_type   : Factor w/ 3 levels "PM01","PM02",..: 3 3 1 1 1 1 2 2 3 1##  $ actual_finish: Date, format: "2008-10-15" "2009-10-19" NA "2008-10-11" ...

I think @Greg Snow's answer is far better, as it does not change the default behaviour of an often used function.

In case you need time also:

setClass('yyyymmdd-hhmmss')setAs("character","yyyymmdd-hhmmss", function(from) as.POSIXct(from, format="%Y%m%d-%H%M%S"))d <- read.table(colClasses="yyyymmdd-hhmmss", text="20150711-130153")str(d)## 'data.frame':    1 obs. of  1 variable:## $ V1: POSIXct, format: "2015-07-11 13:01:53"