Holcombe:ProgrammingInR

SUPA Sydney University Perception and Action Lab Primer editing help refcard

R is an interactive programming language for statistics. The syntax is very idiosyncratic, and not really in a good way. Try R for programmers for a description. However it may have menu-driven versions maybe available R commander we haven't tried that and another one is pmg GTK maybe here

In the lab we have the book Using R for Introductory Statistics. R_Statistics introduces you to R

Dani has posted some example code and graphs on his personal website.

R reference cheatsheet, also a file here Media:Matlab-python-xref.pdf‎ that gives equivalent code for doing array operations in MATLAB, Python, and R plot parameters

There is a wiki with some good tips here. Also Data frame tips, list of R websites

Functions in R can only return one parameter.

dataframe tips

Examining your data frame or object, let's say it's called datos

typeof(datos) #returns "list!"
str(datos) #tells you it's a dataframe, number of observations, columns, etc
head(datos)
str(datos)
summary(datos) #good for ggplot objects also

df$varWithExtraLevels = factor(df$varWithExtraLevels)

length(df) #number of columns of dataframe

names(df) #names of columns of dataframe

library(Hmisc); 
describe(df)

#Calling typeof() on a dataframe returns "list"

rm(objectToBeDeleted)
rm(list = ls())  #Delete nearly everything in memory

expand.grid() to create dataframe with every combination of some factors

Check your counterbalancing in your results file. Make a contingency table,

table(dataRaw$speed,dataRaw$relPhaseOuterRing)

Replace certain value with another

thr$thresh[  thr$task=='ident' ] = NA

Creating Graphs (usu. ggplot2)

how I Holcombe:fit psychometric functions and bootstrap

See http://openwetware.org/wiki/Holcombe:Plotting

Debugging in R

How to examine and try things with a questionable variable within a function?

 ee <<- resultsMeans #make global, violating all principles of good coding #DEBUG
 STOP

After an error, calling traceback() gives you the stack

doing ANOVAs etc

Understanding model formulae

ANOVA with repeated measures walk-through

some aov (ANOVA) explanation

R will assume factor is regressor if numeric

I think I had too many error terms reducing error terms

Anovas with repeated measures can be complicated in R.

We have some R books in the lab

Dealing with circular data

von Mises vs. wrapped Gaussian,

see Swindale, N. V. (1998). Orientation tuning curves: empirical description and estimation of parameters. Biol Cybern, 78(1), 45-56.

Setting up a proxy in R on a Mac

The easiest way to set up a proxy is simply to create a file called ".Rprofile" (make sure the file does not have a .txt or .rtf extension. Textwrangler will automatically give it an extension, it may be best to create the file using Vi in a terminal - using emacs probably won't work) in your user directory (~ or /Users/username/) with the line:

 Sys.setenv(http_proxy=”http://username:password@tcdproxy.tcd.ie:8080″)

Then restart R. This information (and more) can be found on Ken Benoit's webpage

If you're at the Camperdown campus of the University of Sydney, use:

 Sys.setenv(http_proxy=”http://www-cache.usyd.edu.au:8080″)

Note: The following may not necessarily be true anymore. If the below address does not work, use the same one as for Camperdown above. The Cumberland Campus of the University of Sydney, use:

 Sys.setenv(http_proxy=”web-cache-ext.usyd.edu.au:8080″)