On Wed, 12 Aug 2009, Mark Breman wrote:
Hi,
I have a csv file with different datatypes:
2009-01-01, character1, 10, 20.1
2009-01-02, character2, 11, 21.1
(I have attached the file to this post)
I read this file with read.zoo as I want a zoo/xts timeseries:
t = read.zoo("./data.txt", sep=",", dec = ".", header=FALSE)
If I look at the zoo data all integer/numeric columns are read as
character:
str(t)
?zoo? series from 2009-01-01 to 2009-01-02
Data: chr [1:2, 1:3] " character1" " character2" "10" "11" "20.1" "21.1"
- attr(*, "dimnames")=List of 2
..$ : NULL
..$ : chr [1:3] "V2" "V3" "V4"
Index: Class 'Date' num [1:2] 14245 14246
So I try the colClasses parameter with read.zoo but it looks like this does
not make any difference:
t1 = read.zoo("./data.txt", sep=",", dec = ".", header=FALSE,
colClasses=c("Date", "character", "integer", "numeric"))
str(t1)
?zoo? series from 2009-01-01 to 2009-01-02
Data: chr [1:2, 1:3] " character1" " character2" "10" "11" "20.1" "21.1"
- attr(*, "dimnames")=List of 2
..$ : NULL
..$ : chr [1:3] "V2" "V3" "V4"
Index: Class 'Date' num [1:2] 14245 14246
Why does read.zoo ignores the colClasses parameter
zoo objects are a matrix plus an "index" (aka time) attribute (of
arbitrary class). As the data is a matrix, it can only be of one type,
everything numeric typically. Mixed classes would require a data.frame
plus index, which is currently not yet supported.
and how do I get integer/numeric data into my zoo series?
You can read it as a data.frame and convert the character column to
integers if that makes sense for your data:
x <- read.table("data.txt", sep = ",")
x[,2] <- as.numeric(x[,2])
z <- zoo(as.matrix(x[,-1]), as.Date(as.character(x[,1])))
Alternatively, you could store the data as a data.frame of zoo series (a
column in a data.frame can be of class zoo, including factor columns).
hth,
Z
Regards,
-Mark-
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