rserve-simpler¶ ↑

rserve-simpler is a simple interface on top of rserve-client, a fantastic gem that lets a user communicate with R in a straighforward, efficient way.

rserve-client is doing all the heavy lifting and should be consulted for background.

require 'rserve/simpler'
r = Rserve::Simpler.new

# or can initialize a connection held in the 'R' constant:
require 'rserve/simpler/R'
R.do_something_fantastic ...  # ** not a real method

These commands specify ways of talking to your Rserve connection. They differ chiefly in the type of output you’ll receive back from R.

# converse: casts the result with 'to_ruby'
r.converse "mean(c(1,2,3))"  # -> 2.0

# convert: returns the raw Rserve::REXP result (like eval)
rexp = r.convert "mean(c(1,2,3))"  # -> #<Rserve::REXP::Double:0x00000002296498 @payload=[2.0], @attr=nil>
rexp.as_doubles   # -> [2.0]
rexp.to_ruby      # -> 2.0

# command: tell R what to do and only expect boolean reply
r.command "z <- mean(c(1,2,3))"  # -> true
# all variables are persistent in the session and can be retrieved later
r.converse "z"  # -> 2.0

converse/convert/command let you name variables in a hash as a shortcut to ‘assign’. [These examples use Ruby 1.9 hash syntax, but they should work on 1.8 if the hashes are keyed old-style {:key => val}]

r.converse(a: [1,2,3], b: [4,5,6]) { "cor(a,b)" } # -> 1.0
# another form doing the same thing
r.converse("cor(a,b)", a: [1,2,3], b: [4,5,6])

‘>>’ is an alias for converse, so you can write code like this:

r >> "mean(c(1,2,3))"  # -> 2.0
# note: use '.>>' (and parentheses at times) to get proper behavior with multiple args or blocks
r.>> "cor(a,b)", a: [1,2,3], b: [1,2,3]

Data frames are a prominent object in R. Simpler provides a simple ruby DataFrame object.

Column names are derived from the data hash’s keys. Ruby 1.9 hashes keep track of insertion order. Use an OrderedHash (gem install orderedhash) for ruby 1.8, or set colnames.

hash = {
  var1: [1,2,3,4], 
  fac1: [3,4,5,6], 
  res1: [4,5,6,7]
}
# convert with hash.to_dataframe or Rserve::DataFrame.new(hash)
r.command( df: hash.to_dataframe ) do 
  %Q{ 
    pdf("out.pdf")
    plot(df)
    dev.off()
  }
end

The equivalent data frame as above can be generated with an array of Struct objects.

DataRow = Struct.new(:var1, :fac1, :res1)
structs = [
  DataRow.new(1,3,4),
  DataRow.new(2,4,5),
  DataRow.new(3,5,6),
  DataRow.new(4,6,7)
]
datafr = Rserve::DataFrame.from_structs(structs)
reply = r.converse("summary(df)", df: datafr).each_cons(6).to_a
datafr.colnames.zip(reply) {|name,data| puts [name].+(data).join("\n ") }

## outputs -> :
var1
 Min.   :1.00  
 1st Qu.:1.75  
 Median :2.50  
 Mean   :2.50  
 3rd Qu.:3.25  
 Max.   :4.00  
fac1
 Min.   :3.00  
 1st Qu.:3.75  
 ...

Rserve is great for graphical output. Here are some pointers when getting started with plotting:

Plots to x11() are persistent until the script or session ends.

Inside an irb session:

irb>>  r >> "plot(c(1,2,3), c(3,4,5))"
# if you resize a window (at least on Ubuntu) you may need to re-issue the call
irb>>  r >> "plot(c(1,2,3), c(3,4,5))"
# return a list of currently used devices (device 2 is the only one being used)
# to_ruby returns an array of 1 value as a number
irb>>  r >> "dev.list()"
=> 2
# shut off graphics device 2
# [??] sometimes this generates windows 3 & 4, not sure what is happening
irb>> r >> "dev.off(2)"
# shut off all graphics
irb>> r >> "graphics.off()"

In a script, your plot will appear until the script exits. This usually means you’ll miss the display of your plot. Two ways to deal with this:

r >> "plot(c(1,2,3), c(4,5,6))"
sleep(7)  # pause for 7 seconds

r >> "plot(c(1,2,3), c(4,5,6))"
r.pause  # pauses things until a key is pressed in terminal

Files are written below the workdir specified when the Rserve connection was made (see Rserve configuration for background) and this is “/tmp/Rserve” on my system.

r.>> "pdf('output.pdf')", "plot(c(1,2,3),c(4,5,6))", "dev.off()"
# outputs file /tmp/Rserv/conn156/output.pdf
# note the connection number dir!
# (I haven't figured out how to predict this number)

NArray vectors work as input to converse, convert, and command.

• simple option to use pwd as default directory

• quiet the startup of Rserve by default

• wrap graphic output commands

see LICENSE.txt