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Old 06-10-2009, 12:10 PM
Woosuk Jang Woosuk Jang is offline
Join Date: Jun 2009
Posts: 8
read method needed

Is there a method where I can continuously read data from a text file (such that, when a new data is written in that file while program's running, it reads that immediately) ?
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Old 06-12-2009, 03:04 PM
Jeff Jeff is offline
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Join Date: Aug 2008
Posts: 2,454
The methods for reading and writing to files can be found in the Python documentation. What's the reason for reading it immediately after writing it to file?
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Old 06-16-2009, 08:31 AM
Woosuk Jang Woosuk Jang is offline
Join Date: Jun 2009
Posts: 8
Sorry for the confusion last time.
The program is supposed to read from a text file that is being written from another program. In my case the Vizard program is supposed to read a text file that Viewpoint is writing to. So I need a code that can help me to read continuously, because the text file is continuously being written, and I tried different methods with no avail.
This is my code so far:

file1 = 'file_name.txt'
file2 = open('marker.txt','a')

def linecount(fname):
""" Count number of lines in a file."""
f = open(fname)
nr_of_lines = sum(1 for line in f)
return nr_of_lines

def readline ():
j = linecount(file1)
i = 1
count = 0
while count < 30:
j = linecount(file1)
if i <= j:
while i <= j:
line = linecache.getline(file1,i)
i = i + 1
#i = j
yield viztask.waitTime(2)
count = count + 1


So what I did is two loops to read and write each line to a separate file ('marker.txt') as well as trying to continuously read in one second intervals. However, when I tested the program, it only reads up to the lines that were already present in the text file ('file_name.txt' or file1) right at the moment of initiation. Although it recognizes that there are new lines added (j increases) it doesn't read or write the lines.
Hope this is more understandable.
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Old 06-22-2009, 05:49 PM
Jeff Jeff is offline
WorldViz Team Member
Join Date: Aug 2008
Posts: 2,454
Please use code tags when posting code next time. Adding the following made it work for me.
line = linecache.getline(file1,i)
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