[visionegg] Re: how to output the result to a file

Speaking of data output, I've attached some code I wrote in the past
for logging data in a human-readable & machine-readable format, where
you can supply the names of variables in the current space that you'd
like to write to file. It uses what I think is a pretty nasty hack
that probably isn't guaranteed to work in future versions of Python,
but for the time being it's been useful to me.

On Nov 21, 2007 5:20 PM, Eamon Caddigan <ecaddiga@xxxxxxxx> wrote:
> Here's a good tutorial on writing things to files (part of a larger
> good tutorial on python): http://www.diveintopython.org/file_handling/
> file_objects.html#d0e15055
>
> Note that writing to (and reading from) disk is a relatively slow
> operation for a computer. It does its best by buffering output, but
> if your experiment is sensitive to timing issues, it's typically best
> to save data in another structure (e.g., a list of coordinate
> tuples), and only write that info to a file at the end of your trials.
>
> HTH,
> Eamon
>
>
>
> On Nov 21, 2007, at 7:01 PM, Lili Wu wrote:
>
> > Hi,
> > I have a question about how to output the running result of a program.
> > Take the demo of mouseTarget.py for example, I can use "print x,y "
> > to output every mouseposition in the Python Shell window. Is there
> > any method to output this data to a file, like a *.txt file?
> >
> > Thanks!
> >
> > Lili
> >
> > 雅虎邮箱，终生伙伴！
>
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>

# written by Neil Halelamien
#import inspect
import time
import os
import sys

class DataLogger:
    # directory: the directory to save the data file in
    # filetag: an id tag, such as the experiment type and subject ID
    def __init__(self, datadir, filetag):
        #begintime_tag = time.strftime("%Y-%m-%d_%H.%M.%S", time.localtime())
        file_fragment = filetag + '.txt'
        self.filename = os.path.join(datadir, file_fragment)
        os.makedirs(os.path.join(datadir, filetag)) # also create directory 
with same name as datafile
        self.file = open(self.filename, 'w')
    
    # Writes the variables with the specified names out to the file
    # Uses some hacks to access variables from up the stack
    # NOTE: right now doesn't work on member variables, e.g. foo.bar
    def writevars(self, *args):
        f = sys._getframe(1)
        #print f.f_locals
        for varname in args:
            assert type(varname) is str
            vardata = f.f_locals[varname]
            dataline = varname + ' ' + repr(vardata)
            print dataline
            self.file.write(dataline + '\n')
    
    # Should be called when done with DataLogger
    def close(self):
        self.file.close()

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