[R] error in importing text files

[Steve_Friedman at nps.gov]

Eric,

The error suggests that the file  has an inconsistent  number of
attributes.  You should inspect the file to make sure that each line has
the same number of expected attributes (columns). If one or more is
missing, it suggests that the data collection process from the Palm Pilot
is not what you expect it to be. Perhaps, participants, just didn't answer
all of the questions or something like that.



Steve Friedman Ph. D.
Spatial Statistical Analyst
Everglades and Dry Tortugas National Park
950 N Krome Ave (3rd Floor)
Homestead, Florida 33034

Steve_Friedman at nps.gov
Office (305) 224 - 4282
Fax     (305) 224 - 4147


                                                                           
             "Eric McKibben"                                               
             <EMcKibb at clemson.                                             
             edu>                                                       To 
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                                                                   Subject 
                                       [R] error in importing text files   
             05/18/2009 10:42                                              
             AM AST                                                        
                                                                           
                                                                           
                                                                           
                                                                           




Hello All:
I am very new to R and am trying to import some (107) text files into R
while simultaneously manipulating the data into a structure that I can use.
Below is a description of what I am trying to ultimately accomplish.
However, I find that I am unable to even read one file into R using the
read.table function.  I get the following error:
> test<-read.table("test4.txt")
Error in scan(file, what, nmax, sep, dec, quote, skip, nlines, na.strings,
:
  line 16 did not have 8 elements

So, I would like to resolve the error first, and then ultimately accomplish
the goal outlined below.  I understand that my ultimate goal may require
multiple steps.  I am open to that.


First, a little background:  Data were collected from 107 participants on
palm pilots.  Participants were randomly beeped 5 times throughout the day
for 5 days resulting in a total of 25 measurement occasions.  Participants
responded to beeps only when they were able to (not in class, driving,
etc).  Thus, most participants completed far less than 25 measurement
occasions.  During each measurement occasion participants responded to 32
questions by moving a slider on a 100 point scale.  The palms recorded the
date, time, palm pilot ID number, response to the beep (non-response =
-32767), question number, response latency in milliseconds, response to
each question, and three addtiional data points of no interest.  The data
are arranged in an unstacked (long) text file such that each line contains
all of the above information and there are 34 (32 responses plus 2 extra
lines of meaningless data) lines per measurement occasion (upto 850 lines
of data if all 34 lines are present !
 for all 25 measurment occasions). Below is an example of how the data are
arranged.

20080204131646         2        32            560        63  6         0 ""
20080204131646         2        33            152        -1  7         0 ""
20080204150043         2    -32767              0      9999  0     65535 ""
20080204182117         2         1            283        -1  7         0 ""
20080204182117         2         2            838        34  6         0 ""
20080204182117         2         3            266        36  6         0 ""
Year/Month/Day/Time  Palm ID  Response/Q#    Latency  Response  3
meangingless columns    The dataset presented above begins with question 32
of one measurement occasion on Febraury 4, 2008 taken at 13:16:46.  The
next line (33) is in the datafile because participants had to click a
button to exit the measurement occasion.  You then see the beginning of
another measurement occasion (20080204192117) in which the participant did
not respond (-32767).  The next measurement occasion begins on the next
line which actually starts with response 2 because participants were
required to read a screen and click through prior to answering any
questions.  Thus, anytime participants simply read an instruction page
responses are coded as a -1.  What I would like to do is write code to
automatically import these 107 files into R and structure them
appropriately while importing them.  Furthermore, I would like for the code
to use conditional statements so that whenever it encounters a -32767!
  it inserts 32 variables (columns) with missing data and whenever it
encounters a -1 it deletes that column all together.  I would also like the
code to separate the combined year/month/day/time column into 4 separate
columns (year, month, day, time).  Finally, I would like the code to stack
the 32 responses during each measurement occasion so that I have 32 columns
of reponses plus columns for year, month, day, and latency, but leave each
measurment occasion unstacked.

Thanks!

Eric S McKibben
Industrial-Organizational Psychology Graduate Student
Clemson University
Clemson, SC
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