Holcombe:ProgrammingInR

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(doing ANOVAs etc)
 
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[http://rwiki.sciviews.org/doku.php?id=tips:tips#data Data frame tips],  [http://alittleknowledge.wordpress.com/2009/09/11/r-for-pedestrians/ list of R websites]
[http://rwiki.sciviews.org/doku.php?id=tips:tips#data Data frame tips],  [http://alittleknowledge.wordpress.com/2009/09/11/r-for-pedestrians/ list of R websites]
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Functions in R can only return one parameter. Calling typeof() on a dataframe returns "list"!
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Functions in R can only return one parameter.
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Delete nearly everything in memory: rm(list = ls())
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Examining your data matrix or object, let's say it's called ''datos''
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===dataframe tips===
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Examining your data frame or object, let's say it's called ''datos''
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typeof(datos) #returns "list!"
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str(datos) #tells you it's a dataframe, number of observations, columns, etc
  head(datos)
  head(datos)
  str(datos)
  str(datos)
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summary(datos) #good for ggplot objects also
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df$varWithExtraLevels = factor(df$varWithExtraLevels)
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length(df) #number of columns of dataframe
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names(df) #names of columns of dataframe
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library(Hmisc);
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describe(df)
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#Calling typeof() on a dataframe returns "list"
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rm(objectToBeDeleted)
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rm(list = ls())  #Delete nearly everything in memory
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Don't use the function ''attach''. It seems to leave lots of data in the 'environment' that can cause problems later. Also it makes the code harder to understand.
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expand.grid() to create dataframe with every combination of some factors
Check your counterbalancing in your results file. Make a contingency table,
Check your counterbalancing in your results file. Make a contingency table,
  table(dataRaw$speed,dataRaw$relPhaseOuterRing)
  table(dataRaw$speed,dataRaw$relPhaseOuterRing)
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 +
Replace certain value with another
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thr$thresh[  thr$task=='ident' ] = NA
==Creating Graphs (usu. ggplot2)==
==Creating Graphs (usu. ggplot2)==
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In the lab we usually use the package, [http://had.co.nz/ggplot2/ ggplot2], for graphs. Ask Sarah about the ggplot2 book.
 
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For custom colour schemes, the [http://research.stowers-institute.org/efg/R/Color/Chart/ Chart of R Colors] is a helpful resource. The table with named colours is most useful.
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how I [[Holcombe:fit psychometric functions]] and bootstrap
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ggplot2 tips:
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See http://openwetware.org/wiki/Holcombe:Plotting
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last_plot()
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summary(g) gives info about the ggplot struct, if you've created one called g
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order used for scale mapping (color, etc.) is perhaps the order of the levels property of the vector. This gives bizarre results because R's sort(unique(x)) default does not alphabetize strings.
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==Debugging in R==
==Debugging in R==
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   STOP
   STOP
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==fitting psychometric functions==
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After an error, calling traceback() gives you the stack
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Malte Kuss hosts the R library PsychoFun on his personal webpage rather than c-ran server. So you must download is package, unzip it, and install it by inside R going to Packages&Data->Package Installer->Local Package Directory->Install, go inside the PsychoFun directory you've unzipped, and click Open.
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I needed to constrain width of psychometric function to be quite narrow. Prior I was using followed lognormal distribution. Then if want mode to be say .1, have to feed it a mean parameter of -2.3 because ln(.1) = -2. Unfortunately the PsychoFun code doesn't allow using a negative parameter for that prior, so I had to change the code. To do so, you go into the downloaded version of PsychoFun folder before you install it, where you can find PsychoFun.R in the R subdirectory. I commented out line 56. Then have to reinstall with Package Installer inside R, "Local Package Directory" option, after in my case first deleting original PsychoFun installation in /Library/Frameworks/R.framework/Versions/2.10/Resources/library/
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==doing ANOVAs etc==
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[http://ww2.coastal.edu/kingw/statistics/R-tutorials/formulae.html Understanding model formulae]
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Technical Report explains many more terms than JoV article:
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[http://ww2.coastal.edu/kingw/statistics/R-tutorials/repeated.html ANOVA with repeated measures] walk-through
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Acceptance rate:Next sample in chain only accepted if quantity on p.481 of JoV paper is good
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Kinetic, Potential energy from Hamiltonian algorithm
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==doing ANOVAs etc==
 
[http://www.personality-project.org/r/r.anova.html some aov (ANOVA) explanation]
[http://www.personality-project.org/r/r.anova.html some aov (ANOVA) explanation]
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I think I had [http://tolstoy.newcastle.edu.au/R/help/04/08/2136.html too many error terms]
I think I had [http://tolstoy.newcastle.edu.au/R/help/04/08/2136.html too many error terms]
[http://books.google.com.au/books?id=ptbcCBSWvvQC&pg=PA359&lpg=PA359&dq=ANOVA+within-subjects++pooled+error+term&source=bl&ots=73eFDsaw8l&sig=ReTGWRjNFGnYQ4DF-D6qAE9qJgQ&hl=en&ei=cKu4Sd7CPIr2sAPSw4Q8&sa=X&oi=book_result&resnum=8&ct=result reducing error terms]
[http://books.google.com.au/books?id=ptbcCBSWvvQC&pg=PA359&lpg=PA359&dq=ANOVA+within-subjects++pooled+error+term&source=bl&ots=73eFDsaw8l&sig=ReTGWRjNFGnYQ4DF-D6qAE9qJgQ&hl=en&ei=cKu4Sd7CPIr2sAPSw4Q8&sa=X&oi=book_result&resnum=8&ct=result reducing error terms]
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[http://blog.gribblelab.org/2009/03/09/repeated-measures-anova-using-r/ Anovas with repeated measures] can be complicated in R.
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We have some R books in the lab
==Dealing with circular data==
==Dealing with circular data==
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==Setting up a proxy in R on a Mac==
==Setting up a proxy in R on a Mac==
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The easiest way to set up a proxy is simply to create a file called ".Rprofile" in your user directory (~ or Users/username/) with the line:
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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:
<code>
<code>
   Sys.setenv(http_proxy=”http://username:password@tcdproxy.tcd.ie:8080″)
   Sys.setenv(http_proxy=”http://username:password@tcdproxy.tcd.ie:8080″)
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This information (and more) can be found on [http://www.kenbenoit.net/?p=261 Ken Benoit's webpage]
This information (and more) can be found on [http://www.kenbenoit.net/?p=261 Ken Benoit's webpage]
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For Sydney Uni, use:
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If you're at the Camperdown campus of the University of Sydney, use:
<code>
<code>
   Sys.setenv(http_proxy=”http://www-cache.usyd.edu.au:8080″)
   Sys.setenv(http_proxy=”http://www-cache.usyd.edu.au:8080″)
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</code>
 +
 +
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:
 +
<code>
 +
  Sys.setenv(http_proxy=”web-cache-ext.usyd.edu.au:8080″)
</code>
</code>

Current revision

Members

Alex Holcombe
Sarah McIntyre
Fahed Jbarah
• Shih-Yu Lo
• Patrick Goodbourn
Lizzy Nguyen
Alumni


Technical

Skills Checklist
Python Programming
Psychopy/VisionEgg Installation Notes
R analysis,plot,stats
Statistics
Buttonbox
Verifying timing
Programming Cheat Sheets


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″)
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