I have a txt file that gets appended with data over a time event. The data comes from an RFID reader and is dumped to the file by the RFID software. I want to poll that file several times over the time period of the event to capture the current data in the RFID reader.
When I read the data I want to be able to compare the current data to the date from the last time I read it and only process the data appended since the last time it was read. The first time I read the data, it might look like this: AU08JEDD011485H14472402210 AU08JEDD020163C14472502210 AU08JEDD005029C14480102210 AU08JEDD004923H14482002210 AU08AWOL000799H14483902210 The next time it might look like this (with data appended to it) AU08JEDD011485H14472402210 AU08JEDD020163C14472502210 AU08JEDD005029C14480102210 AU08JEDD004923H14482002210 AU08AWOL000799H14483902210 AU08AWOL000120H14495902210 AU08ARPU050241H14511702210 IF08DRTO008074H14520202210 IF08DRTO008089H14521102210 IF08DRTO008077H14553602210 IF08CHES000023H14594902210 What I want to do is compare the old data (lets day it is saved to a file called 'lastdata.txt') with the new data (lets day it is saved to a file called 'currentdata.txt') and save the new appended data to a variable which I HTTP POST to a website where I process the data for display to interested parties. In the example below I am trying to save the new appended data to a file called "out.txt" I have looked at difflib.context_diff but I cannot get the syntax correct. This is what I have taken from an example from this page http://docs.python.org/library/difflib.html. One thing I do not understand is what do I do with: fromfile='before.py', tofile='after.py' in the example code. ********** import sys import difflib sys.stdout = open("out.txt","w") f1 = open(r'C:\Users\Owner\Desktop\lastdata.txt', 'r') read_data1 = f1.read() f1.close() f2 = open(r'C:\Users\Owner\Desktop\currentdata.txt', 'r') read_data2 = f2.read() f2.close() for line in context_diff(read_data1, read_data2, fromfile='before.py', tofile='after.py'): sys.stdout.write(line) *************** for line in context_diff(read_data1, read_data2, fromfile='before.py', tofile='after.py'): is the line that causes the syntax error. I would hope that when the script worked that "out.txt" would have the appended data. I would then copy currentdata.txt to lastdata.txt. No need to clear out the data in currentdata.txt as the next dump will overwrite that data. Any help or insights appreciated, thanks... -- http://mail.python.org/mailman/listinfo/python-list
