Source code for IMMA.read

# Read in IMMA records from files.

import re     #  Regular Expressions
from structure import attachment
from structure import parameters
from structure import definitions

# Convert a single-digit base36 value to base 10
def _decode_base36(t): 
    return '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'.find(t)

# Extract the parameter values from the string representation
#  of an attachment
def _decode(as_string,        # String representation of the attachment
            attachment_n):    # Attachment number
    if( as_string== None ):
        raise ValueError("Bad IMMA string: No data to decode")
    params=parameters["%02d" % attachment_n]
    defns=definitions["%02d" % attachment_n]

    Decoded={}
    Position = 0;
    for param in params:
        if ( defns[param][0] != None ):
            Value = as_string[Position:Position+defns[param][0]]
            Position += defns[param][0]
        else:                  # Undefined length - so slurp all the data
            Value = as_string[Position:len(as_string)]
            Value = Value.rstrip("\n")
            Position = len(as_string)

    # Blanks mean value is undefined
        if( re.search("\S",Value) == None ):
            Value = None
            Decoded[param]=Value
            continue    #  Next parameter

        if ( defns[param][6] == 2 ):
            Value = _decode_base36(Value)

        if ( defns[param][6] == 1 ):
            Value = int(Value)

        if ( defns[param][5] != None and
             defns[param][5] != 1.0 ):
            Value = int(Value)*defns[param][5];
        Decoded[param]=Value
    return Decoded

# Make an iterator returning IMMA records from a file
[docs]class get: """Turn an imma file into an iterator providing its records. Args: filename (:obj:`str`): Name of file containing IMMA records. Returns: :obj:`func`: iterator - call ``next()`` on this to get the next record. """ def __init__(self, filename): self.fh=open(filename,'r') def __iter__(self): return self def next(self): # Python 3: def __next__(self) line = self.fh.readline(); if(line == ""): raise StopIteration line=line.rstrip("\n") # Remove trailing newline Attachment_n = 0; # Core always first Length = 108; record={} record['attachments']=[] while ( len(line) > 0 ): if ( Length != None and Length > 0 and len(line) < Length ): sfmt = "%%%ds" % (Length-len(line)) line += sfmt % " " record.update(_decode(line,Attachment_n)) record['attachments'].append(int(Attachment_n)) if ( Length==None or Length == 0 ): break line = line[Length:len(line)] if ( len(line) > 0 ): Attachment_n = int(line[0:2]) Length = line[2:4] line = line[4:len(line)] if Attachment_n==8: Length='102' # Ugly! if( re.search("\S",Length)==None): Length = None if ( Length != None ): Length = int(Length) if ( Length != 0 ): Length = int(Length)-4 if(attachment["%02d" % Attachment_n]==None ): raise ValueError("Bad IMMA string","Unsupported attachment ID %d" % Attachment_n)
return record # Function to read in all the records in a file
[docs]def read(filename): """Load all the records from an imma file. Just the same as ``list(IMMA.get(filename)``. Args: filename (:obj:`str`): Name of file containing IMMA records. Returns: :obj:`list`: List of records - each record is a :obj:`dict`: """
return list(get(filename))