when using Python's open() function to read a binary file, only part of the file is read

Question

I am trying to read data from a jpg file using the open() function in python. For some reason, some of the file data is being lost. Here is what I tried:

file = open(imageDir, 'r')
data = file.read()
print data

When I try to re-write the data into a new file, the new file is corrupt.

How do you know that? Also, what is the meaning of "lines" in a jpg file? — DeepSpace
– DeepSpace, Commented Oct 26, 2019 at 18:01

Joshua Fox · Accepted Answer · 2019-10-26 18:03:27Z

3

Use 'rb' for binary file. Also, I suggest you not use dir for what is actually a filename; and use the context syntax for the read operation.

with file = open(filename, 'rb')
     data = file.read()

answered Oct 26, 2019 at 18:03

Joshua Fox

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2 Comments

DeepSpace Over a year ago

dir is a built-in global function, one more reason why it's a bad variable name

4xy Over a year ago

Actually it's invalid syntax...

4xy · Accepted Answer · 2019-10-26 18:04:17Z

1

You should open file in binary mode like this

file = open(dir, 'rb')

By default it’s opened in text mode

answered Oct 26, 2019 at 18:04

4xy

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