Hi,

On Nov 11, 2009, at 1:06 PM, separent wrote:


#Hello,

#I loaded data using read.table - I needed to convert a row in the data
frame to date class:

data

V1          V2          V3          V4
1  2008-05-19  2008-04-19  2008-03-21  2008-02-22
2 38.16999817 30.70999908 36.86000061 35.18999863
3 37.47999954 29.95000076 36.45999908 35.36000061
4 37.47999954 30.14999962 36.47000122 35.36000061
5 37.84999847 30.56999969 36.84000015 35.74000168
6 38.38999939 31.14999962 37.34000015 36.27000046
7 39.11000061 31.90999985 38.02999878 36.97999954
8 39.81000137 32.65000153 38.68000031 37.63999939
9 40.47000122 33.34999847 39.27999878 38.27000046

data[1,]
         V1         V2         V3         V4
1 2008-05-19 2008-04-19 2008-03-21 2008-02-22

dates1<-as.Date(data[1,])

I think this should work if data[1,] returns a vector of characters:

R> d <- c("2008-05-19", "2008-05-30")
R> dd <- as.Date(d)
R> is(dd)
[1] "Date"     "oldClass"

Is your first row being treated as factors? Maybe if you convert to character first it should work?

R> dates1<-as.Date(as.character(data[1,]))

But the fact that it works for as.Date(data[1,1]) make it a bit weird ...

-steve

do not know how to convert 'dates[1,]' to class "Date"

# However, I can individually convert them all:

dates1.1<-as.Date(data[1,1])

dates1.1
[1] "2008-05-19"

# How can I change the class of the date over the entire row (my original
file contains more than one hundred rows)?
# Thank you very much.
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--
Steve Lianoglou
Graduate Student: Computational Systems Biology
  |  Memorial Sloan-Kettering Cancer Center
  |  Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact

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