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Goal: Learn how to read ASCII data in CDAT.

• Use Python “string” Module
• Use VCDAT
• In general use genutil.ASCII.readAscii
  

genutil.ASCII.readAscii( text_file ,header=0, ids=None, shape=None,
    next='------',separators=[';',',',':'])
Reads data from an ascii file
    Usage :::
    vars = genutil.ASCII.readAscii( text_file ,header=0, ids=None, shape=None, next='------',separators=[';',',',':'])
    :::

    Options :::
        text_file  :: ASCII File to read from.
        header     :: (0) Number of header lines, these lines will be skipped.
        ids        :: (None) use the values in this list as variable ids (1 per variable returned)
        shape      :: (None) use the tuple/list in this list as the final shape of the variable read.
        next       :: ('------') character string marking separation between variables
        separators :: ([';',',', ':']) List of character recognized as column separator
    Output :::
        vars       :: List containing transient variable possibly named after ids and reshaped from the 'shape' option.

• If data are in columns use genutil.ASCII.read_col

genutil.ASCII.read_col( text_file ,header=0, cskip=0, 
    cskip_type='columns', axis=0, ids=None, idrow=0,
    separators=[';',',', ':'])
 
Reads column-stored data from ASCII files
    Usage:::
     vars = genutil.ASCII.read_col( text_file ,header=0, cskip=0, cskip_type='columns', axis=False, ids=None, idrow=False, separators=[';',',', ':'])

    Options :::
        text_file  :: ASCII File to read from.
        header     :: (0) Number of header lines, these lines will be skipped.
        cskip      :: (0) Number of 'column'/'character' to skip (dummy column)
        cskip_type :: ('column') is 'cskip'  a number of 'column' or 'character' to skip?
        axis       :: (False)  Use as the values for the first column as variable axis (x values in y(x))
        idrow      :: (False) Is the first row representing the ids of var generated ?
        ids        :: (None) use the values in this list as variable ids (1 per column returned)
        separators :: ([';',',', ':']) List of character recognized as column separator
    Output :::
        vars       :: List containing 1 transient varialbe per column in the files.
                      Variable ids are optionaly determined by first row.
                      Variable axis may be the first column

Python "string"  example:

import sys,MV

# First of all we need to open the ASCII file
# For this we used the Python built-in command "open"
f=open(sys.prefix+'/sample_data/test_col.asc')

# Now we need to read its content
# To read all of its content we use the "readlines" command
# This returns a list of strings, each element of the list represents
# one line in the file
lines=f.readlines()

# Note to read one line at a time (inside a loop for example, if the ascii file is too big
# You can also f.readline()

# Now we can loop through the lines and look at the content
data1=[]
data2=[]

for line in lines:
    # Splits the line into a list of string with seprartion 
    # when it finds space or tabs or return    
    sp=line.split() 

    # Now try to see if the first element is a number, if not skip
    # we are only interested in the 2nd and third column here
    try:
        val1=float(sp[1])   # second column
        val2=float(sp[2])   # third column
        
        data1.append(val1)
        data2.append(val2)

    except:
        pass       #  we didn't have 2 float at the begining of this line


# Now converts the 2 datasets to MV for use in other CDAT Packages
data1=MV.array(data1,id='dataset1')
data2=MV.array(data2,id='dataset2')

# Just for fun prints the average of data1
print MV.average(data1)

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