The documentation observes that cor accepts an optional second argument. The following works:
> df1 <- data.frame(a=1:8, b=rep(c(-1, 1), 4),
+ c=rep(c(-1, 1), each=4))
> cor(df1[,1], df1[, -1])
b c
[1,] 0.2182179 0.8728716
>
hope this helps. spencer graves
[EMAIL PROTECTED] wrote:
Dear R help community,
I want to calculate correlations between environment parameters and species
abundance data. When I use the cor() for my table (121 columns 91 rows) R
generates a dataset with the correlations between all columns;
1) How can I limit the calculations to the correlations of only the first column with every other ? (Or:) How can I extract the line/row in question from the cor() dataset produced by R ?
2) I assume that with one continuous factor and the other binary (0/1), cor() gives the point-biserial correlation coefficient, but how can I find the
method used by R ?
3) I was not able to import (from "Excel") the whole 121x67 table, for instance I divided it into pieces. Is there a simple solution to import the whole file ?
4) In the end I want to test the correlation coefficients. Where do I find an appropriated test for the point biserial correlation ? Can R calculate the coefficient and test it for all data in one step ?
I just started working & learning with R, but even after reading the R-help and Introduction to R, I still have big difficulties, so Thanks in advance for your help !!
Arne Saatkamp
Arne Saatkamp Inst. f. Biol. II - Abt. f. Geobotanik Schänzlestr. 1 79104 Freiburg Germany
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