LOADING DATA INTO ARRAYS

[John Hunter]

>>>>> "satish" == satish k chimakurthi <skchim0 at engr.uky.edu> writes:

    satish> I have written the following code which is not working for
    satish> some reason.  Can anyone suggest any changes:
[snip]
    satish>  xval,yval=string.split(line) ValueError: unpack list of
    satish> wrong size

The problem is with this line of code.

     xval,yval=string.split(line)

As the error indicates you are unpacking the results of the split
(which has 3 elements x,y,z) into 2 variables xval, yval.  You need to
do

   xval, yval, zval = line.split()

But then xval, yval and zval are strings and I bet you want them to be
floats.  So this would be better

   xval, yval, zval = map(float, line.split())

Finally, if you are doing number crunching, you will be much happier
with Numeric http://pfdubois.com/numpy/.  If holding the whole list in
memory is not a problem before initializing to array, you can do

  from Numeric import array
  a = array([float(val) for val in line.split() 
                        for line in file('myfile.dat')])

This uses list comprehensions rather than map to do the float
conversions but it's the same idea.

Now you can access the first row with a[0], or the first column with
a[:,0], etc....

Numeric comes with lots of support for analysis, etc...  In addition,
many of the python plotting packages and other analysis packages are
designed to work with Numeric.

JDH