Hello Vishal
Maybe this is what you want?
x<-c(0.34,0.36,3)
y<-c(0.56,0.76,4)
a<-data.frame(x,y)
>a
x y
1 0.34 0.56
2 0.36 0.76
3 3.00 4.00
a$diff<-(log(a$x))
a$diff2<-(log(a$y))
>a
x y diff diff2
1 0.34 0.56 -1.078810 -0.5798185
2 0.36 0.76 -1.021651 -0.2744368
3 3.00 4.00 1.098612 1.3862944
and if you wnat to coerce the first row to a whatever
value just type
a[1,]<-NA
Cheers
A
----- Messaggio originale -----
Da: Vishal Belsare <[EMAIL PROTECTED]>
A: r-help@r-project.org
Inviato: Mercoledì 9 gennaio 2008, 23:16:38
Oggetto: [R] diff in a dataframe
I have a dataframe say:
date price_g price_s
0.34 0.56
0.36 0.76
. .
. .
. .
and so on. say, 1000 rows.
Is it possible to add two columns to this dataframe, by computing say
diff(log(price_g) and diff(log(price_s)) ?
The elements in the first row of these columns cannot be computed, but
can I coerce this to happen and assign a missing value there? It would
be really great if I could do that, because in this case I don't have
to re-index my transformed series to the dates again in a new
dataframe.
Thanks in anticipation.
Vishal Belsare
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