[R] as.Date from data.frame

[separent]

Hello Gentlemen,

All of your answers were helpfull. Indeed, 'as.is=TRUE' or
'stringsAsFactors=FALSE' avoid importing as factors, as it did when I
imported the table without specifying anything. However, data frames will
not allow different datatypes within a single column, so, for time series, I
should work with a transpose of the table. However, when the time series is
the label of a profile, I should read the table with 'header = TRUE'.

In other words:
* Plotting values of a column (let's say againts observation number) for a
selected time (where time is the name of the series): import data with
'header = TRUE'
* Plotting the evolution of the values for a single observation number
against time: 'header = TRUE' & transpose & 'as.is=TRUE'

Kind Regards,

Serge-Étienne Parent
Golder Associés
Canada



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,])
> 
> 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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