Re: writing serial port data to the gzip file

2006-12-18 Thread jim-on-linux 



If someone hasn't already commented, 

Aside from any other problems, the file you are 
trying to write to is (opened)?? in the w mode. 
Every time a file is opened in the 'w' mode, 
everything in the file is deleted.

If you open a file in the 'a' mode, then 
everything in the file is left untouched and the 
new data is appended to the end of the file.

Your while loop is deleting everything in the file 
on each loop with the 'w' mode.

try, 
vfile = open('vfile', 'a')
rather than 
vfile = open('vfile', 'w')

jim-on-linux
http:\\www.inqvista.com


 while 1:
 g=gzip.GzipFile(/root/foofile.gz,w)
 while dataOnSerialPort():
 g.write(data)
 else: g.close()



On Sunday 17 December 2006 20:06, Petr Jakes 
wrote:
 I am trying to save data it is comming from the
 serial port continually for some period.
 (expect reading from serial port is 100% not a
 problem) Following is an example of the code I
 am trying to write. It works, but it produce an
 empty gz file (0kB size) even I am sure I am
 getting data from the serial port. It looks
 like g.close() does not close the gz file.
 I was reading in the doc:

 Calling a GzipFile object's close() method does
 not close fileobj, since you might wish to
 append more material after the compressed
 data...

 so I am completely lost now...

 thanks for your comments.
 Petr Jakes
  snippet of the code  
 def dataOnSerialPort():
 data=s.readLine()
 if data:
 return data
 else:
 return 0

 while 1:
 g=gzip.GzipFile(/root/foofile.gz,w)
 while dataOnSerialPort():
 g.write(data)
 else: g.close()
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Re: writing serial port data to the gzip file

2006-12-18 Thread Petr Jakes 
Maybe I am missing something. Expect data is comming continually to the
serial port for the period say 10min. (say form the GPS), than it stops
for 1 minute and so on over and over. I would like to log such a data
to the different gzip files.
My example was written just for the simplicity (I was trying to
demonstrate the problem, it was not the real code and I was really
tired trying to solve it by myself, sorry for the bugy example)

the better way how to write such a infinite loop can be probably:
= 8 =
g=0
x=0
while 1:
if not g:
x+=1
g=gzip.GzipFile(/root/foofile%s.gz % x,w)
data=dataOnSerialPort()
while data:
myFlag=1
g.write(data)
data=dataOnSerialPort():
else:
if myFlag:
g.close()
pring g
myFlag=0

But it looks like g.close() method does not close the file (while
trying to print the g object, it  still exists)


 Your while loop is discarding result of dataOnSerialPort, so you're
 probably writing empty string to the file many times. Typically this
 kind of loop are implemented using iterators. Check if your s object
 (is it from external library?) already implements iterator. If it does
 then

 for data in s:
 g.write(data)

 is all you need. If it doesn't, you can use iter to create iterator for
 you:
 
 for data in iter(s.readLine, ''):
 g.write(data)
 
   -- Leo

-- 
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Re: writing serial port data to the gzip file

2006-12-18 Thread Petr Jakes 
Hi Dennis,
thanks for your reply.
Dennis Lee Bieber napsal:
  def dataOnSerialPort():
  data=s.readLine()

   Unless you are using a custom serial port module, that should be
 s.readline()
sorry for the typo

  if data:
  return data
  else:
  return 0

   This if statement is meaningless -- if data evaluates to false,
 return a numeric value that evaluates to false.
I see, it is OK just to return data (or an empty string )

 
  while 1:
  g=gzip.GzipFile(/root/foofile.gz,w)
  while dataOnSerialPort():
  g.write(data)

   data is an uninitialized value here
  else: g.close()

   And what is the purpose of closing the file if you immediately turn
 around and create it again (assuming gzip.GzipFile() behaves as open()
 does, a mode of w means delete the old file and create a new one.
 There is NO exit from the above.

   Since I can't read your mind with regards to some of your looping...

 s = ... #somewhere you had to open the serial port

 g = gzip.GzipFile(/root/foofile.gz, w)
 while True:
   data = s.readline()
   if not data: break
   g.write(data)
 g.close()

what I am trying to say is g.close() does not close the g file (try to
add the line print g after g.close())
Petr

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writing serial port data to the gzip file

2006-12-17 Thread Petr Jakes 
I am trying to save data it is comming from the serial port continually
for some period.
(expect reading from serial port is 100% not a problem)
Following is an example of the code I am trying to write. It works, but
it produce an empty gz file (0kB size) even I am sure I am getting data
from the serial port. It looks like g.close() does not close the gz
file.
I was reading in the doc:

Calling a GzipFile object's close() method does not close fileobj,
since you might wish to append more material after the compressed
data...

so I am completely lost now...

thanks for your comments.
Petr Jakes
 snippet of the code  
def dataOnSerialPort():
data=s.readLine()
if data:
return data
else:
return 0

while 1:
g=gzip.GzipFile(/root/foofile.gz,w)
while dataOnSerialPort():
g.write(data)
else: g.close()

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Re: writing serial port data to the gzip file

2006-12-17 Thread Leo Kislov 

Petr Jakes wrote:
 I am trying to save data it is comming from the serial port continually
 for some period.
 (expect reading from serial port is 100% not a problem)
 Following is an example of the code I am trying to write. It works, but
 it produce an empty gz file (0kB size) even I am sure I am getting data
 from the serial port. It looks like g.close() does not close the gz
 file.
 I was reading in the doc:

 Calling a GzipFile object's close() method does not close fileobj,
 since you might wish to append more material after the compressed
 data...

 so I am completely lost now...

 thanks for your comments.
 Petr Jakes
  snippet of the code  
 def dataOnSerialPort():
 data=s.readLine()
 if data:
 return data
 else:
 return 0

 while 1:
 g=gzip.GzipFile(/root/foofile.gz,w)
 while dataOnSerialPort():
 g.write(data)
 else: g.close()

Your while loop is discarding result of dataOnSerialPort, so you're
probably writing empty string to the file many times. Typically this
kind of loop are implemented using iterators. Check if your s object
(is it from external library?) already implements iterator. If it does
then

for data in s:
g.write(data)

is all you need. If it doesn't, you can use iter to create iterator for
you:

for data in iter(s.readLine, ''):
g.write(data)

  -- Leo

-- 
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