Re: [R] difficulty in Formatting time series data

Sun, 22 Apr 2012 11:31:29 -0700 


On Apr 22, 2012, at 2:12 PM, Raghuraman Ramachandran wrote:
I tried downloading using as.is and have also provided the dput below. The date for example is 20/4/2012 and wday gives 2 instead of 6? Thanks for all 
your help.


str(test1)

'data.frame':   1825 obs. of  7 variables:
$ Date : chr "20/04/2012" "19/04/2012" "18/04/2012" "17/04/2012" ... 
$ Open     : num  2.33 2.35 2.35 2.34 2.32 2.34 2.3 2.28 2.29 2.28 ...
$ High     : num  2.34 2.36 2.38 2.34 2.35 2.36 2.32 2.29 2.33 2.3 ...
$ Low      : num  2.31 2.33 2.34 2.3 2.31 2.32 2.29 2.25 2.28 2.28 ...
$ Close    : num  2.31 2.35 2.36 2.33 2.31 2.32 2.31 2.26 2.3 2.29 ...
$ Volume : int 5366000 5382000 9606000 9596000 5941000 10332000 7000000 
9636000 6019000 3279000 ...
$ Adj.Close: num  2.31 2.35 2.36 2.33 2.31 2.32 2.31 2.26 2.3 2.29 ...

wday(test$Date[1])

[1] 2
You are skipping a couple of essential steps. The wday() function is unable to infer that you are using a non-standard date format. (I don't think it would even work if you were using YYYY-MM-DD.) Read up on : 

?DateTimeClasses
?as.Date
?strptime

--
David.


wday(test1$Date[1])

[1] 2

test1%Date[1]

Error: unexpected input in "test1%Date[1]"

test1$Date[1]

[1] "20/04/2012"


dput(test1)

structure(list(Date = c("20/04/2012", "19/04/2012", "18/04/2012",
"17/04/2012", "16/04/2012", "13/04/2012", "12/04/2012", "11/04/2012",
"10/04/2012", "09/04/2012", "05/04/2012", "04/04/2012", "03/04/2012",
"02/04/2012", "30/03/2012", "29/03/2012", "28/03/2012", "27/03/2012",
"26/03/2012", "23/03/2012", "21/03/2012", "20/03/2012", "19/03/2012",
"16/03/2012", "15/03/2012", "14/03/2012", "13/03/2012", "12/03/2012",
"09/03/2012", "08/03/2012", "07/03/2012", "06/03/2012", "05/03/2012",
"02/03/2012", "01/03/2012", "29/02/2012", "28/02/2012", "27/02/2012",
"24/02/2012", "23/02/2012", "22/02/2012", "21/02/2012", "20/02/2012",
"17/02/2012", "16/02/2012", "15/02/2012", "14/02/2012", "13/02/2012",
"10/02/2012", "09/02/2012", "08/02/2012", "07/02/2012", "06/02/2012",
"03/02/2012", "02/02/2012", "01/02/2012", "31/01/2012", "30/01/2012",
"27/01/2012", "26/01/2012", "25/01/2012", "20/01/2012", "19/01/2012",
"18/01/2012", "17/01/2012", "16/01/2012", "13/01/2012", "12/01/2012",
"11/01/2012", "10/01/2012", "09/01/2012", "06/01/2012", "05/01/2012",
"04/01/2012", "03/01/2012", "30/12/2011", "29/12/2011", "28/12/2011",
"27/12/2011", "23/12/2011", "22/12/2011", "21/12/2011", "20/12/2011",
"19/12/2011", "16/12/2011", "15/12/2011", "14/12/2011", "13/12/2011",
"12/12/2011", "09/12/2011", "08/12/2011", "07/12/2011", "06/12/2011",
"05/12/2011", "02/12/2011", "01/12/2011", "30/11/2011", "29/11/2011",
"28/11/2011", "25/11/2011", "24/11/2011", "23/11/2011", "22/11/2011",
"21/11/2011", "18/11/2011", "17/11/2011", "16/11/2011", "15/11/2011",
"14/11/2011", "11/11/2011", "10/11/2011", "09/11/2011", "08/11/2011",
"04/11/2011", "03/11/2011", "02/11/2011", "01/11/2011", "31/10/2011",
"28/10/2011", "27/10/2011", "25/10/2011", "24/10/2011", "21/10/2011",
"20/10/2011", "19/10/2011", "18/10/2011", "17/10/2011", "14/10/2011",
"13/10/2011", "12/10/2011", "11/10/2011", "10/10/2011", "07/10/2011",
"06/10/2011", "05/10/2011", "04/10/2011", "03/10/2011", "30/09/2011",
"29/09/2011", "28/09/2011", "27/09/2011", "26/09/2011", "23/09/2011",
"22/09/2011", "21/09/2011", "20/09/2011", "19/09/2011", "16/09/2011",
"15/09/2011", "14/09/2011", "13/09/2011", "12/09/2011", "09/09/2011",
"08/09/2011", "07/09/2011", "06/09/2011", "05/09/2011", "02/09/2011",
"01/09/2011", "31/08/2011", "29/08/2011", "26/08/2011", "25/08/2011",
"24/08/2011", "23/08/2011", "22/08/2011", "19/08/2011", "18/08/2011",
"17/08/2011", "16/08/2011", "15/08/2011", "12/08/2011", "11/08/2011",
"10/08/2011", "08/08/2011", "05/08/2011", "04/08/2011", "03/08/2011",
"02/08/2011", "01/08/2011", "29/07/2011", "28/07/2011", "27/07/2011",
"26/07/2011", "25/07/2011", "22/07/2011", "21/07/2011", "20/07/2011",
"19/07/2011", "18/07/2011", "15/07/2011", "14/07/2011", "13/07/2011",
"12/07/2011", "11/07/2011", "08/07/2011", "07/07/2011", "06/07/2011",
"05/07/2011", "04/07/2011", "01/07/2011", "30/06/2011", "29/06/2011",
"28/06/2011", "27/06/2011", "24/06/2011", "23/06/2011", "22/06/2011",
"21/06/2011", "20/06/2011", "17/06/2011", "16/06/2011", "15/06/2011",
"14/06/2011", "13/06/2011", "10/06/2011", "09/06/2011", "08/06/2011",
"07/06/2011", "06/06/2011", "03/06/2011", "02/06/2011", "01/06/2011",
"31/05/2011", "30/05/2011", "27/05/2011", "26/05/2011", "25/05/2011",
"24/05/2011", "23/05/2011", "20/05/2011", "19/05/2011", "18/05/2011",
"16/05/2011", "13/05/2011", "12/05/2011", "11/05/2011", "10/05/2011",
"09/05/2011", "06/05/2011", "05/05/2011", "04/05/2011", "03/05/2011",
"29/04/2011", "28/04/2011", "27/04/2011", "26/04/2011", "25/04/2011",
"21/04/2011", "20/04/2011", "19/04/2011", "18/04/2011", "15/04/2011",
"14/04/2011", "13/04/2011", "12/04/2011", "11/04/2011", "08/04/2011",
"07/04/2011", "06/04/2011", "05/04/2011", "04/04/2011", "01/04/2011",
"31/03/2011", "30/03/2011", "29/03/2011", "28/03/2011", "25/03/2011",
"24/03/2011", "23/03/2011", "22/03/2011", "21/03/2011", "18/03/2011",
"17/03/2011", "16/03/2011", "15/03/2011", "14/03/2011", "11/03/2011",
"10/03/2011", "09/03/2011", "08/03/2011", "07/03/2011", "04/03/2011",
"03/03/2011", "02/03/2011", "01/03/2011", "28/02/2011", "25/02/2011",
"24/02/2011", "23/02/2011", "22/02/2011", "21/02/2011", "18/02/2011",
"17/02/2011", "16/02/2011", "15/02/2011", "14/02/2011", "11/02/2011",
"10/02/2011", "09/02/2011", "08/02/2011", "07/02/2011", "02/02/2011",
"01/02/2011", "31/01/2011", "28/01/2011", "27/01/2011", "26/01/2011",
"25/01/2011", "24/01/2011", "21/01/2011", "20/01/2011", "19/01/2011",
"18/01/2011", "17/01/2011", "14/01/2011", "13/01/2011", "12/01/2011",
"11/01/2011", "10/01/2011", "07/01/2011", "06/01/2011", "05/01/2011",
"04/01/2011", "03/01/2011", "31/12/2010", "30/12/2010", "29/12/2010",
"28/12/2010", "27/12/2010", "24/12/2010", "23/12/2010", "22/12/2010",
"21/12/2010", "20/12/2010", "17/12/2010", "16/12/2010", "15/12/2010",
"14/12/2010", "13/12/2010", "10/12/2010", "09/12/2010", "08/12/2010",
"07/12/2010", "06/12/2010", "03/12/2010", "02/12/2010", "01/12/2010",
"30/11/2010", "29/11/2010", "26/11/2010", "25/11/2010", "24/11/2010",
"23/11/2010", "22/11/2010", "19/11/2010", "18/11/2010", "16/11/2010",
"15/11/2010", "12/11/2010", "11/11/2010", "10/11/2010", "09/11/2010",
"08/11/2010", "04/11/2010", "03/11/2010", "02/11/2010", "01/11/2010",
"29/10/2010", "28/10/2010", "27/10/2010", "26/10/2010", "25/10/2010",
"22/10/2010", "21/10/2010", "20/10/2010", "19/10/2010", "18/10/2010",
"15/10/2010", "14/10/2010", "13/10/2010", "12/10/2010", "11/10/2010",
"08/10/2010", "07/10/2010", "06/10/2010", "05/10/2010", "04/10/2010",
"01/10/2010", "30/09/2010", "29/09/2010", "28/09/2010", "27/09/2010",
"24/09/2010", "23/09/2010", "22/09/2010", "21/09/2010", "20/09/2010",
"17/09/2010", "16/09/2010", "15/09/2010", "14/09/2010", "13/09/2010",
"09/09/2010", "08/09/2010", "07/09/2010", "06/09/2010", "03/09/2010",
"02/09/2010", "01/09/2010", "31/08/2010", "30/08/2010", "27/08/2010",
"26/08/2010", "25/08/2010", "24/08/2010", "23/08/2010", "20/08/2010",
"19/08/2010", "18/08/2010", "17/08/2010", "16/08/2010", "13/08/2010",
"12/08/2010", "11/08/2010", "10/08/2010", "06/08/2010", "05/08/2010",
"04/08/2010", "03/08/2010", "02/08/2010", "30/07/2010", "29/07/2010",
"28/07/2010", "27/07/2010", "26/07/2010", "23/07/2010", "22/07/2010",
"21/07/2010", "20/07/2010", "19/07/2010", "16/07/2010", "15/07/2010",
"14/07/2010", "13/07/2010", "12/07/2010", "09/07/2010", "08/07/2010",
"07/07/2010", "06/07/2010", "05/07/2010", "02/07/2010", "01/07/2010",
"30/06/2010", "29/06/2010", "28/06/2010", "25/06/2010", "24/06/2010",
"23/06/2010", "22/06/2010", "21/06/2010", "18/06/2010", "17/06/2010",
"16/06/2010", "15/06/2010", "14/06/2010", "11/06/2010", "10/06/2010",
"09/06/2010", "08/06/2010", "07/06/2010", "04/06/2010", "03/06/2010",
"02/06/2010", "01/06/2010", "31/05/2010", "27/05/2010", "26/05/2010",
"25/05/2010", "24/05/2010", "21/05/2010", "20/05/2010", "19/05/2010",
"18/05/2010", "17/05/2010", "14/05/2010", "13/05/2010", "12/05/2010",
"11/05/2010", "10/05/2010", "07/05/2010", "06/05/2010", "05/05/2010",
"04/05/2010", "03/05/2010", "30/04/2010", "29/04/2010", "28/04/2010",
"27/04/2010", "26/04/2010", "23/04/2010", "22/04/2010", "21/04/2010",
"20/04/2010", "19/04/2010", "16/04/2010", "15/04/2010", "14/04/2010",
"13/04/2010", "12/04/2010", "09/04/2010", "08/04/2010", "07/04/2010",
"06/04/2010", "05/04/2010", "01/04/2010", "31/03/2010", "30/03/2010",
"29/03/2010", "26/03/2010", "25/03/2010", "24/03/2010", "23/03/2010",
"22/03/2010", "19/03/2010", "18/03/2010", "17/03/2010", "16/03/2010",
"15/03/2010", "12/03/2010", "11/03/2010", "10/03/2010", "09/03/2010",
"08/03/2010", "05/03/2010", "04/03/2010", "03/03/2010", "02/03/2010",
"01/03/2010", "26/02/2010", "25/02/2010", "24/02/2010", "23/02/2010",
"22/02/2010", "19/02/2010", "18/02/2010", "17/02/2010", "12/02/2010",
"11/02/2010", "10/02/2010", "09/02/2010", "08/02/2010", "05/02/2010",
"04/02/2010", "03/02/2010", "02/02/2010", "01/02/2010", "29/01/2010",
"28/01/2010", "27/01/2010", "26/01/2010", "25/01/2010", "22/01/2010",
"21/01/2010", "20/01/2010", "19/01/2010", "18/01/2010", "15/01/2010",
"14/01/2010", "13/01/2010", "12/01/2010", "11/01/2010", "08/01/2010",
"07/01/2010", "06/01/2010", "05/01/2010", "04/01/2010", "31/12/2009",
"30/12/2009", "29/12/2009", "28/12/2009", "24/12/2009", "23/12/2009",
"22/12/2009", "21/12/2009", "18/12/2009", "17/12/2009", "16/12/2009",
"15/12/2009", "14/12/2009", "11/12/2009", "10/12/2009", "09/12/2009",
"08/12/2009", "07/12/2009", "04/12/2009", "03/12/2009", "02/12/2009",
"01/12/2009", "30/11/2009", "26/11/2009", "25/11/2009", "24/11/2009",
"23/11/2009", "20/11/2009", "19/11/2009", "18/11/2009", "17/11/2009",
"16/11/2009", "13/11/2009", "12/11/2009", "11/11/2009", "10/11/2009",
"09/11/2009", "06/11/2009", "05/11/2009", "04/11/2009", "03/11/2009",
"02/11/2009", "30/10/2009", "29/10/2009", "28/10/2009", "27/10/2009",
"26/10/2009", "23/10/2009", "22/10/2009", "21/10/2009", "20/10/2009",
"19/10/2009", "16/10/2009", "15/10/2009", "14/10/2009", "13/10/2009",
"12/10/2009", "09/10/2009", "08/10/2009", "07/10/2009", "06/10/2009",
"05/10/2009", "02/10/2009", "01/10/2009", "30/09/2009", "29/09/2009",
"28/09/2009", "25/09/2009", "24/09/2009", "23/09/2009", "22/09/2009",
"18/09/2009", "17/09/2009", "16/09/2009", "15/09/2009", "14/09/2009",
"11/09/2009", "10/09/2009", "09/09/2009", "08/09/2009", "07/09/2009",
"04/09/2009", "03/09/2009", "02/09/2009", "01/09/2009", "31/08/2009",
"28/08/2009", "27/08/2009", "26/08/2009", "25/08/2009", "24/08/2009",
"21/08/2009", "20/08/2009", "19/08/2009", "18/08/2009", "17/08/2009",
"14/08/2009", "13/08/2009", "12/08/2009", "11/08/2009", "07/08/2009",
"06/08/2009", "05/08/2009", "04/08/2009", "03/08/2009", "31/07/2009",
"30/07/2009", "29/07/2009", "28/07/2009", "27/07/2009", "24/07/2009",
"23/07/2009", "22/07/2009", "21/07/2009", "20/07/2009", "17/07/2009",
"16/07/2009", "15/07/2009", "14/07/2009", "13/07/2009", "10/07/2009",
"09/07/2009", "08/07/2009", "07/07/2009", "06/07/2009", "03/07/2009",
"02/07/2009", "01/07/2009", "30/06/2009", "29/06/2009", "26/06/2009",
"25/06/2009", "24/06/2009", "23/06/2009", "22/06/2009", "19/06/2009",
"18/06/2009", "17/06/2009", "16/06/2009", "15/06/2009", "12/06/2009",
"11/06/2009", "10/06/2009", "09/06/2009", "08/06/2009", "05/06/2009",
"04/06/2009", "03/06/2009", "02/06/2009", "01/06/2009", "29/05/2009",
"28/05/2009", "27/05/2009", "26/05/2009", "25/05/2009", "22/05/2009",
"21/05/2009", "20/05/2009", "19/05/2009", "18/05/2009", "15/05/2009",
"14/05/2009", "13/05/2009", "12/05/2009", "11/05/2009", "08/05/2009",
"07/05/2009", "06/05/2009", "05/05/2009", "04/05/2009", "30/04/2009",
"29/04/2009", "28/04/2009", "27/04/2009", "24/04/2009", "23/04/2009",
"22/04/2009", "21/04/2009", "20/04/2009", "17/04/2009", "16/04/2009",
"15/04/2009", "14/04/2009", "13/04/2009", "09/04/2009", "08/04/2009",
On Sun, Apr 22, 2012 at 6:41 PM, Jeff Newmiller <jdnew...@dcn.davis.ca.us >wrote: 


On Sun, 22 Apr 2012, Hasan Diwan wrote:

Raghu,


On 22 April 2012 09:53, Raghuraman Ramachandran <optionsra...@gmail.com

wrote:
I have a data frame (from CSV file) which has its first column called 
Date.
The Date is in the format mm/dd/yyyy. I was trying to get the weekday for these dates and I tried using wday() and day.of.week() functions and both of them gave me precisely the wrong answers. I think the issue lies in 
the
proper formatting of dates. The class of this column is a factor class 
and
hence I tried converting into POSIXlt, xts, zoo objects and yet I could 
not
get the weekday correctly. Anyone has any suggestions please?



Try this:
# assume dataIn is where the CSV files data is...
dataIn$Date <- as.POSIXct(dataIn$Date, format='%m/%d/%y')
By far the most common error I see is failing to import the Date column as character, instead allowing the import function to convert it to factor, after which computations (such as the above suggestion) use the hidden factor index instead of the visible character representation, which further mystifies beginners. The conversion above will only work correctly if the 
column was imported as character.  E.g.

dataIn <- read.csv( file="yourdatafile", as.is=TRUE )
OP: Use the str() function to see what types you are working with, and in future R-help queries send dput() of the data and code you have tried if we are to be able to reproduce your attempts effectively rather than reading 
your mind.
dataIn <- cbind(dataIn, day.of.week = format(dataIn$Date, format='%A') 



Why not just

dataIn$day.of.week <- weekdays( dataIn$Date )

?

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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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