Wednesday, May 18, 2011

phylogenetic signal simulations

I did a little simulation to examine how K and lambda vary in response to tree size (and how they compare to each other on the same simulated trees). I use Liam Revell's functions fastBM to generate traits, and phylosig to measure phylogenetic signal.

Two observations: 



First, it seems that lambda is more sensitive than K to tree size, but then lambda levels out at about 40 species, whereas K continues to vary around a mean of 1.

Second, K is more variable than lambda at all levels of tree size (compare standard error bars).

Does this make sense to those smart folks out there?




Tuesday, May 17, 2011

A simple function for plotting phylogenies in ggplot2

UPDATE: Greg jordan has a much more elegant way of plotting trees with ggplot2. See his links in the comments below.


I wrote a simple function for plotting a phylogeny in ggplot2. However, it only handles a 3 species tree right now, as I haven't figured out how to generalize the approach to N species.

Any ideas on how to improve this?



Friday, May 13, 2011

plyr's idata.frame VS. data.frame

I had seen the function idata.frame in plyr before, but not really tested it. From the plyr documentation:

"An immutable data frame works like an ordinary data frame, except that when you subset it, it
returns a reference to the original data frame, not a a copy. This makes subsetting substantially
faster and has a big impact when you are working with large datasets with many groups."

For example, although baseball is a data.frame, its immutable counterpart is a reference to it:

> idata.frame(baseball)
<environment: 0x1022c74e8>
attr(,"class")
[1] "idf"         "environment"


Here are a few comparisons of operations on normal data frames and immutable data frames. Immutable data frames don't work with the doBy package, but do work with aggregate in base functions.  Overall, the speed gains using idata.frame are quite impressive - I will use it more often for sure.


Get the github code below here.





Here's the comparisons of idata.frames and data.frames:

> # load packages
require(plyr); require(reshape2)
 
> # Make immutable data frame
baseball_i <- idata.frame(baseball)
 
> # Example 1 - idata.frame more than twice as fast
system.time( replicate(50, ddply( baseball, "year", summarise, mean(rbi))) )
   user  system elapsed 
 14.812   0.252  15.065 
> system.time( replicate(50, ddply( baseball_i, "year", summarise, mean(rbi))) )
   user  system elapsed 
  6.895   0.020   6.915 
> # Example 2 - Bummer, this does not work with idata.frame's
> colwise(max, is.numeric) ( baseball ) # works year stint g ab r h X2b X3b hr rbi sb cs bb so ibb hbp sh sf gidp 1 2007 4 165 705 177 257 64 28 73 NA NA NA 232 NA NA NA NA NA NA > colwise(max, is.numeric) ( baseball_i ) # doesn't work Error: is.data.frame(df) is not TRUE
> # Example 3 - idata.frame twice as fast
system.time( replicate(100, baseball[baseball$year == "1884", ] ) )
   user  system elapsed 
  1.155   0.048   1.203 
> system.time( replicate(100, baseball_i[baseball_i$year == "1884", ] ) )
   user  system elapsed 
  0.598   0.011   0.609 
> # Example 4 - idata.frame faster
system.time( replicate(50, melt(baseball[, 1:4], id = 1) ) )
   user  system elapsed 
 16.587   1.169  17.755 
> system.time( replicate(50, melt(baseball_i[, 1:4], id = 1) ) )
   user  system elapsed 
  0.869   0.196   1.065 
> # And you can go back to a data frame by 
d <- as.data.frame(baseball_i)
str(d)
 
'data.frame': 21699 obs. of  23 variables:
 $ id   : chr  "ansonca01" "forceda01" "mathebo01" "startjo01" ...
 $ year : int  1871 1871 1871 1871 1871 1871 1871 1872 1872 1872 ...
 $ stint: int  1 1 1 1 1 1 1 1 1 1 ...
 $ team : chr  "RC1" "WS3" "FW1" "NY2" ...
 $ lg   : chr  "" "" "" "" ...
 $ g    : int  25 32 19 33 29 29 29 46 37 25 ...
 $ ab   : int  120 162 89 161 128 146 145 217 174 130 ...
 $ r    : int  29 45 15 35 35 40 36 60 26 40 ...
 $ h    : int  39 45 24 58 45 47 37 90 46 53 ...
 $ X2b  : int  11 9 3 5 3 6 5 10 3 11 ...
 $ X3b  : int  3 4 1 1 7 5 7 7 0 0 ...
 $ hr   : int  0 0 0 1 3 1 2 0 0 0 ...
 $ rbi  : int  16 29 10 34 23 21 23 50 15 16 ...
 $ sb   : int  6 8 2 4 3 2 2 6 0 2 ...
 $ cs   : int  2 0 1 2 1 2 2 6 1 2 ...
 $ bb   : int  2 4 2 3 1 4 9 16 1 1 ...
 $ so   : int  1 0 0 0 0 1 1 3 1 0 ...
 $ ibb  : int  NA NA NA NA NA NA NA NA NA NA ...
 $ hbp  : int  NA NA NA NA NA NA NA NA NA NA ...
 $ sh   : int  NA NA NA NA NA NA NA NA NA NA ...
 $ sf   : int  NA NA NA NA NA NA NA NA NA NA ...
 $ gidp : int  NA NA NA NA NA NA NA NA NA NA ...
 $ teamf: Factor w/ 132 levels "ALT","ANA","ARI",..: 99 127 51 79 35 35 122 86 16 122 ...
> # idata.frame doesn't work with the doBy package
require(doBy)
summaryBy(rbi ~ year, baseball_i, FUN=c(mean), na.rm=T)
Error in as.vector(x, mode) : 
  cannot coerce type 'environment' to vector of type 'any'
> # But idata.frame works with aggregate in base (but with minimal speed gains)
# and aggregate is faster than ddply of course 
system.time( replicate(100, aggregate(rbi ~ year, baseball, mean) ) )
   user  system elapsed 
  4.117   0.423   4.541 
> system.time( replicate(100, aggregate(rbi ~ year, baseball_i, mean) ) )
   user  system elapsed 
  3.908   0.383   4.291 
> system.time( replicate(100, ddply( baseball_i, "year", summarise, mean(rbi)) ) )
   user  system elapsed 
 14.015   0.048  14.082 
Created by Pretty R at inside-R.org

Thursday, May 12, 2011

google reader

I just realized that the gists code blocks don't show up in Google Reader, so you have to click the link to my blog to see the gists. Apologies for that!

-S

Wednesday, May 11, 2011

Comparison of functions for comparative phylogenetics

With all the packages (and beta stage groups of functions) for comparative phylogenetics in R (tested here: picante, geiger, ape, motmot, Liam Revell's functions), I was simply interested in which functions to use in cases where multiple functions exist to do the same thing. I only show default settings, so perhaps these functions would differ under different parameter settings.  [I am using a Mac 2.4 GHz i5, 4GB RAM]

Get motmot here: https://r-forge.r-project.org/R/?group_id=782
Get Liam Revell's functions here: http://anolis.oeb.harvard.edu/~liam/R-phylogenetics/


> # Load 
require(motmot); require(geiger); require(picante)
source("http://anolis.oeb.harvard.edu/~liam/R-phylogenetics/phylosig/v0.3/phylosig.R")
source("http://anolis.oeb.harvard.edu/~liam/R-phylogenetics/fastBM/v0.4/fastBM.R")
 
# Make tree
tree <- rcoal(10)
 




# Transform branch lengths
> system.time( replicate(1000, transformPhylo(tree, model = "lambda", lambda = 0.5)) ) # motmot
   user  system elapsed 
  1.757   0.004   1.762 
> system.time( replicate(1000, lambdaTree(tree, 0.9)) ) # geiger
   user  system elapsed 
  3.708   0.008   3.716 
>   # motmot wins!!!


# Simulate trait evolution
system.time( replicate(1000, transformPhylo.sim(tree, model = "bm")) ) # motmot
   user  system elapsed 
  3.732   0.007   3.741 
> system.time( replicate(1000, rTraitCont(tree, model = "BM")) ) # ape
   user  system elapsed 
  0.312   0.009   0.321 
> system.time( replicate(1000, fastBM(tree)) ) # Revell
   user  system elapsed 
  1.315   0.005   1.320 
>   # ape wins!!!

# Phylogenetically independent contrasts
trait <- rnorm(10)
names(trait) <- tree$tip.label
 
> system.time( replicate(10000, pic.motmot(trait, tree)$contr[,1])  ) # motmot
   user  system elapsed 
  3.062   0.007   3.070 
> system.time( replicate(10000, pic(trait, tree)) ) # ape
   user  system elapsed 
  2.846   0.007   2.853 
>   # ape wins!!!

# Phylogenetic signal, Blomberg's K
> system.time( replicate(100, Kcalc(trait, tree))  ) # picante
   user  system elapsed 
  1.311   0.005   1.316 
> system.time( replicate(100, phylosig(tree, trait, method = "K")) ) # Revell
   user  system elapsed 
  0.201   0.000   0.202 
>   # Liam Revell wins!!!

# Ancestral character state estimation
> system.time( replicate(100, ace(trait, tree)$ace) ) # ape
   user  system elapsed 
  4.988   0.018   5.007 
> system.time( replicate(100, getAncStates(trait, tree)) ) # geiger
   user  system elapsed 
  2.253   0.005   2.258 
>   # geiger wins!!!

Created by Pretty R at inside-R.org


__________
It's hard to pick an overall winner because not all functions are available in all packages, but there are definitely some functions that are faster than others.

Tuesday, May 3, 2011

Treebase trees from R

UPDATE: See Carl Boettiger's functions/package at Github for searching Treebase here.



Treebase is a great resource for phylogenetic trees, and has a nice interface for searching for certain types of trees. However, if you want to simply download a lot of trees for analyses (like that in Davies et al.), then you want to be able to access trees in bulk (I believe Treebase folks are working on an API though). I wrote some simple code for extracting trees from Treebase.org.

It reads an xml file of (in this case consensus) URL's for each tree, parses the xml, makes a vector of URL's, reads the nexus files with error checking, remove trees that gave errors, then a simple plot looking at metrics of the trees.

Is there an easier way to do this?