[R] correlation, import of large tables, test for point-biserial c.c.?

ArneSaatkamp@gmx.de ArneSaatkamp at gmx.de
Fri Jul 11 16:01:15 CEST 2003

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


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