Homework Problem 2, Due Wednesday February 6.
---------------------------------------------

Either follow the course web-page links or directly access
the (compressed) text data-file

http://www.math.umd.edu/~evs/s798c/Data/exampfram.asc.gz

(You may have to create a new ASCII data-file by copying from the
browser window to a word-processor and saving the file `as text'.)

   (a) Create the data-frame "exampfram" consisting only of the
columns IDNUM DTH EVTTIME TRTGP LOGBILI AGEVAR CIRRH
from the indicated text data-file by using the "read.table" R 
function. Make sure that these column labels are the column names.
In your resulting data frame, check whether the "class" values of 
the TRTGP and CIRRH columns are respectively "character" and "logical"
and if not, change them to be this way.

(When the data are first inputted by read.table, character columns 
are by default converted to something that we will study later 
called a "Factor".)

   (b) Create the same data-frame, this time called "exampfram2", by
inputting the data as a giant vector using "scan" (after skipping
the first header line, if you wish) and then doing Splus operations
upon that vector. Make sure that the columns of this data-frame are
all numeric except that the TRTGP column is character-type and
CIRRH is Boolean, i.e., "logical". To achieve this you will have
to make a character matrix into a data-frame, and then redefine the
types" of the columns using R functions like as.numeric() and  
as.logical().

   (c) Show that your two data-frames in (a) and (c) are identical.

   (d) Create and display a matrix whose first column is the vector
of minima of the numeric variables in `exampfram' and whose
second column is the corresponding vector of maximum values.