How do I compare files?

[Clay Hobbs]

I am making a program that (with urllib) that downloads two jpeg files
and, if they are different, displays the new one. I need to find a way
to compare two files in Python. How is this done?

-- Ratfink

[GHZ]

Re: How do I compare files?

On Jul 23, 1:27 am, Clay Hobbs <c...@lakeserv. netwrote:

I am making a program that (with urllib) that downloads two jpeg files
and, if they are different, displays the new one.  I need to find a way
to compare two files in Python.  How is this done?
>
-- Ratfink

import hashlib

file = open(path)
m = hashlib.md5()
m.update(file.r ead())
digest = m.hexdigest()
file.close()


and compare the digest on both files

[Matimus]

Re: How do I compare files?

On Jul 22, 4:27 pm, Clay Hobbs <c...@lakeserv. netwrote:

I am making a program that (with urllib) that downloads two jpeg files
and, if they are different, displays the new one.  I need to find a way
to compare two files in Python.  How is this done?
>
-- Ratfink

Do you just want to check to see if they are the same? Or do you
actually want to know what the differences are?

import urllib

data1 = urllib.urlopen( "http://url.of.jpg1").r ead()
data2 = urllib.urlopen( "http://url.of.jpg2").r ead()

if data1 == data2:
print "they are the same"


Doing a regular text diff won't tell you much. You could use PIL and
do all sorts of image manipulation though. You might generate an image
of the difference between each pixel.
Something like this:

import Image
import ImageChops
import urllib

data1 = urllib.urlopen( "http://url.of.jpg1").r ead()
data2 = urllib.urlopen( "http://url.of.jpg2").r ead()

im1 = Image.fromstrin g(data1)
im2 = Image.fromstrin g(data2)
result = ImageChops.diff erence(im1, im2)
result.save("re sult_image.jpg" )


Read up on PIL:

http://www.pythonware.com/library/pil/handbook/index.htm

Matt

[Larry Bates]

Re: How do I compare files?

Clay Hobbs wrote:

I am making a program that (with urllib) that downloads two jpeg files
and, if they are different, displays the new one. I need to find a way
to compare two files in Python. How is this done?
>
-- Ratfink
>

Use md5 to calculate checksum:

import md5

md5file1 = md5.md5(open(fi lename1).read() ).hexdigest()
md5file2 = md5.md5(open(fi lename2).read() ).hexdigest()

if md5file1 != mdfile2:
#
# Do whatever you want
#

-Larry

[Clay Hobbs]

Re: How do I compare files?


On Tue, 2008-07-22 at 17:29 -0700, Matimus wrote:

On Jul 22, 4:27pm, Clay Hobbs <c...@lakeserv. netwrote:

I am making a program that (with urllib) that downloads two jpeg files
and, if they are different, displays the new one. I need to find a way
to compare two files in Python. How is this done?

-- Ratfink

>
Do you just want to check to see if they are the same? Or do you
actually want to know what the differences are?
>
import urllib
>
data1 = urllib.urlopen( "http://url.of.jpg1").r ead()
data2 = urllib.urlopen( "http://url.of.jpg2").r ead()
>
if data1 == data2:
print "they are the same"
>

I just wanted to see if they are different. The code I was using that
didn't work was almost the same, except that the lines that download the
files didn't end in .read(). Thank you for your help

-- Ratfink