I have a text (csv) file) with two columns: dates and numeric measurements.
I read it using read.table and the dates get read as a factor, with as many
levels as there are dates in the data.  How can I create a matrix-like data
structure (data frame?) which has one column of “real” dates (a vector of
dates, not a factor variable) and one column of the numeric measurements?
The strptime function converts the data into dates, but the naļve

 

foo <- read.table(…)                               # foo is a 2-column data
frame with the first column a factor (of dates) and the second column a
return vector

foo.dates <- strptime(fool[,1], format)       

cbind(foo.dates, foo[,2]) 

 

does not work (because foo.dates is not a vector) and produces a wrong
dimension error:

 

Warning message:

In cbind(foo.dates, foo[,2]) :

  number of rows of result is not a multiple of vector length (arg 1)

 

I am sure this is a very basic question on types, but I have spent hours on
this without much luck.  Any ideas/suggestions would be greatly welcome.

 

Thank you in advance.

 

 

Achilles Venetoulias
Tel: (212) 988-2276
axilleas@stanfordalumni.org

 


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