On 04.03.2011 11:38, Dmitrij Kudriavcev wrote:
Hello
Let's say, my data.frame is
symbol,day,value
A, 2010-01-01, 0.8888
A, 2010-01-02, 0.6666
B, 2010-01-01, 0.7777
i need to get matrix as
See ?reshape, in this case if you data.frame is in dat:
reshape(dat, v.names="value", direction="wide",
idvar="day", timevar="symbol")
Uwe Ligges
, A, B
2010-01-01, 0.8888, 0.7777
2010-01-02, 0.6666, NA
where A and B is columns name and date used as row name
I found a way how to do it with tapply function, is it a best way (i will
need to do this pretty offen and wish to save some time)
Cheers,
Dima
2011/3/4 Ivan Calandra<ivan.calan...@uni-hamburg.de>
Hi,
Let's say your data.frame is called df:
df<- data.frame(a=rnorm(10), b=rnorm(10))
data.matrix<- as.matrix(df)
This should work, but be careful with coercion if you have different modes
in your data.frame
HTH,
Ivan
PS: next time, provide a reproducible example, using dput() for example
Le 3/4/2011 07:08, Dmitrij Kudriavcev a écrit :
Hello
I'm a new in R
I have a large data.frame "s" (this is actualy just a table in mysql) :
names(s)
[1] "symbols", "day", "value"
I need to convert it to simple matrix. I have define this matrix like
this:
data.matrix<- matrix(nrow=nDays, ncol=nSymbols, dimnames=list(days,
symbols))
then i just copy values to the matrix using for() loop, but it seems to
take
very long time. Is is a more fast way to do it in R? I know, what i can
just
gyve s$value as source data to the matrix, but problem is, what for some
symbols couple days could be just missed.
Cheers,
Dima
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and provide commented, minimal, self-contained, reproducible code.
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
