[R] Regarding the 'R' Load Command

[Gavin Simpson]

I think the answer is clear from the error: R thinks the type of data in
the components of 'testmurali' do not match those of the data used to
fit the original randomForest.

The OP should go back to his model fitting code and do

str(obj)

where 'obj' is the name of his original data object used to fit the
randomForest and compare it with

str(testmurali)

to see why the types of data are different. Look for variables that were
factors or characters in one data set and numeric/integer in the other.
This smells like a data import issue...

If revelation still doesn't occur Murali, *please* follow Steve's
suggestions and post and message that shows exactly (i.e. the R code
executed) along side a data set *we* can load into R without jumping
through hoops or having to divine what your data look like using a
crystal ball or ESP.

HTH

G

On Wed, 2010-05-19 at 12:24 -0400, Steve Lianoglou wrote:
> Hi Murali,
> 
> I'm sorry, but you're making this too difficult to provide any help.
> Describing what your data structures are and contain is too tedious to
> follow, and end up being rather ambiguous anyway.
> 
> My first guess: by your error message, perhaps the columns of the data
> to predict on are different than the training.
> 
> If you want to get help, please provide your data in a form that we
> can test against. Look at this post by Hadley Wickham to help you do
> that:
> http://gist.github.com/270442
> 
> In particular, not the use of "dput" that you should use so we can
> paste the result in our workspace and get the data objects you try to
> describe. So, to be clear: send us a chunk of text we can paste into R
> that will recreate a workspace that can reproduce your problem. Please
> trim your data files to be only as large as necessary (eg. provide 3
> observations instead of 300)
> 
> Thanks,
> -steve
> 
> On Wed, May 19, 2010 at 11:40 AM, Godavarthi, Murali
> <MGodavarthi at dpscs.state.md.us> wrote:
> > Hi Steve,
> >
> > Thanks so much for your inputs! I was actually trying to implement your
> > suggestions, I get the below error (please see the results of predict
> > command below).
> >
> > What we are trying to do is to feed in values for about 23
> > characteristics of an individual, and use the randomForest() function to
> > determine if the individual is a violent offender. Expected output is 0
> > or 1, indicating yes/no.
> >
> > Am I going wrong again? Here is what I was doing:
> >
> > 1) Created a text file with following data:
> > "imurder" "itheft" "irobbery" "iassault" "idrug" "iburglary" "igun"
> > "psych" "Freq" "priors" "firstage" "intage" "sex" "race" "marstat"
> > "empac" "educ" "zipcode" "suspendmn" "drugs" "alco" "probation" "parole"
> > "10" 0 0 0 1 0 0 0 0 0 58 19 19 "1" "BLACK" "SINGLE" "UNEMPLD" 0 21215 0
> > 0 0 1 0
> >
> > The above format in which the text file was created is in the same
> > format as the one which is already working, but has characteristics of
> > about 290 individuals fed-in instead of just one individual as above.
> > Not sure why this doesn't work!
> >
> >
> > 2) Executed the below command sequence:
> >
> >
> >> library(randomForest)
> > randomForest 4.5-34
> > Type rfNews() to see new features/changes/bug fixes.
> >
> >> load("C://Program Files//R//R-2.10.1//bin//rfoutput")
> >
> >> testmurali<-read.table("ex.data",T)
> >
> >> load(testmurali)
> > Error in load(testmurali) : bad 'file' argument
> >
> >> load("testmurali")
> >
> >> names(testmurali)
> >  [1] "imurder"   "itheft"    "irobbery"  "iassault"  "idrug"
> > "iburglary" "igun"      "psych"     "Freq"      "priors"
> > [11] "firstage"  "intage"    "sex"       "race"      "marstat"   "empac"
> > "educ"      "zipcode"   "suspendmn" "drugs"
> > [21] "alco"      "probation" "parole"
> >
> >> predict(rfoutput,newdata=testmurali,type="response")
> > Error in predict.randomForest(rfoutput, newdata = testmurali, type =
> > "response") :
> >  Type of predictors in new data do not match that of the training data.
> >>
> >
> > The model rfoutput used in the above predict command is also based on a
> > working example with similar data.
> >
> >
> > Also, does load command accept a data string input directly (without
> > storing it into a file and then providing path of the file as a string)?
> >
> > Please suggest. Thanks in advance!
> >
> >
> > Best Regards,
> > Murali Godavarthi
> > 410-585-3746 (w)
> >
> > ITCD - DPSCS Data Mining
> >
> >
> >
> >
> >
> >
> > -----Original Message-----
> > From: Steve Lianoglou [mailto:mailinglist.honeypot at gmail.com]
> > Sent: Tuesday, May 18, 2010 4:13 PM
> > To: Godavarthi, Murali
> > Cc: r-help at r-project.org
> > Subject: Re: [R] Regarding the 'R' Load Command
> >
> > Hi,
> >
> > On Tue, May 18, 2010 at 2:49 PM, Godavarthi, Murali
> > <MGodavarthi at dpscs.state.md.us> wrote:
> >> Hi,
> >>
> >> I'm new to 'R' and need some help on the "Load" command. Any responses
> >> will be highly appreciated. Thanks in advance!
> >>
> >> As per manuals, the "Load" command expects a binary file input that is
> >> saved using a "save" command.
> >
> > Or a path to the file ...
> >
> >> However it is required that we need to
> >> call the 'R' program from
> >>
> >> Java web application using RJava, and pass a string to the 'R" program
> >> instead of a binary file. Is it possible?
> >
> > Yes, pay closer attention to the description for the "file" argument
> > in the load function (see ?load):
> >
> > """a (readable binary) connection **or a character string** giving the
> > name of the file to load"""
> >
> > (emphasis mine)
> >
> >> I was exploring the options of using TextConnections, file connections
> >> and other types of connections in order to read a stream of input
> >> (either from a file, stdin etc). I am able to read the string, but the
> >> Save and Load commands are not accepting the string input. Here is the
> >> sequence of commands I tried running, and the error received. There is
> >> no clue on this error, especially when trying to use the eval function
> >> in randomForest package, even on the internet. Can anyone help please!
> >>
> >>> library(randomForest)
> >>
> >> randomForest 4.5-34
> >>
> >> Type rfNews() to see new features/changes/bug fixes.
> >>
> >>
> >>
> >>> load("C://Program Files//R//R-2.10.1//bin//rfoutput")
> >>
> >>
> >>
> >>> zz <- file("ex.data", "w")
> >>
> >>
> >>
> >>> cat("\"imurder\" \"itheft\" \"irobbery\" \"iassault\" \"idrug\"
> >> \"iburglary\" \"igun\" \"psych\" \"Freq\" \"priors\" \"firstage\"
> >> \"intage\" \"sex\" \"race\" \"marstat\" \"empac\"
> >>
> >> \"educ\" \"zipcode\" \"suspendmn\" \"drugs\" \"alco\" \"probation\"
> >> \"parole\"",file = zz, sep = "\n", fill = TRUE)
> >>
> >>
> >>
> >>> cat("\"10\" 0 0 0 1 0 0 0 0 0 58 19 19 \"1\" \"BLACK\" \"SINGLE\"
> >> \"UNEMPLD\" 0 21215 0 0 0 1 0",file = zz, sep = "\n", fill = TRUE)
> >
> > What are you trying to do here?
> > It looks like you want to save a table of sorts. First create your
> > data into a data.frame, then save that data.frame to a file using
> > write.table (or write.csv, etc).
> >
> >>> save(zz, file = "testmurali", version = 2)
> >
> > You're saving a file "object" here, not the contents of the file.
> > Once you successfully serialize your data into a text file, just load
> > it from "like normal" using read.table (or similar).
> >
> > Anyway, I'm not sure what we're talking about here, but in short:
> >
> > 1. You need to make sure that you are correctly saving what you think
> > you're saving.
> > 2. You can pass a character string to the `load` function, so you can
> > send it through (over from) java as  you wich.
> > 3. I don't think you really want to deal with load/save here, because
> > it looks like you are dealing with some tab delimited file -- in which
> > case use read.table (or similar) and load it that way. You can, of
> > course, still use save/load, but make sure you save/load the right
> > thing (not a file object like you're doing here).
> >
> > --
> > Steve Lianoglou
> > Graduate Student: Computational Systems Biology
> >  | Memorial Sloan-Kettering Cancer Center
> >  | Weill Medical College of Cornell University
> > Contact Info: http://cbio.mskcc.org/~lianos/contact
> >
> 
> 
> 

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