Learn how to read a binary file in Python using a buffer. This is how computer systems read data such as JPEG images.
Python can create files for humans to read and it can also create files intended for only the computer to read.
In the previous steps you have been writing and reading data to text files. For each project text files were created and saved in a manner that a human can read if they wished, but in reality the text files have already been interpreted by the computer. Computers do not understand human language and so values are written in a way that a computer can process, known as binary.
Binary files can be used to store any data; for example, a JPEG image is a binary file designed to be read by a computer system. The data inside a binary file is stored as raw bytes, which is not human readable.
Using a binary file
Here is a short program. Read the code line by line; can you work out what the code will do?
data = [100,24,255]
buffer = bytes(data)
print(buffer)
f = open("binary.txt", "bw")
f.write(buffer)
f.close()
How does this code work?
The program starts by creating a list called data, containing three numbers. The data list is then converted to bytes (binary numbers) and stored in the buffer variable, which is then printed to the screen. The list has been converted from something you can read into something that is more efficient for a computer system to handle.
A new file called binary.txt is created and the mode set to bw so that bytes can be written into the file, making it a binary file.
The contents of the buffer variable are then written to this file, which is then closed.
Test the code
Copy the code above into your Python editor, save it, and run the code. You can look at the contents of binary.txt using a text editor.
Does it match what you saw in the REPL/console?
Your text editor has tried to open the file, but despite trying it has failed to read the contents correctly. This is because the text editor is trying to interpret the file contents as text.
Reading the file
Reading binary files is very similar to reading text files. Have a look at this code and see if you can work out what it does.
f = open("binary.txt", "br")
binary = f.read()
print(binary)
data = list(binary)
print(data)
f.close()
This code opens the file and sets the mode to binary read, "br". It then reads the contents of the file into the variable binary and prints it to the screen.
The contents of the binary variable are still formatted as bytes. This is converted back into a list using the list() function. This list is then stored in the variable data, having been restored to its original format.
When you run this code, you should see the following:
- The list is printed once after it has been converted into binary, and again after the file has been read.
- The original list converted back from the binary data.
In this step you learnt more about how Python can work with files, for both humans and machines to understand.
Can you think of another type of binary file? Add your suggestions to the comments section.
FAQs
Text files are organized around lines, each of which ends with a newline character ('\n'). The source code files are themselves text files. A binary file is the one in which data is stored in the file in the same way as it is stored in the main memory for processing.
How to handle binary files in Java? ›
We create an InputStream object using the FileInputStream and specify the file name. We use the read() method to read binary data from input stream storing each byte in an integer variable. We convert each byte to its corresponding ASCII character using the typecasting and print it to console.
How binary files are better than text files? ›
Purely size-wise, it is better to use binary. In ASCII representation, full expansion of a double is about 16+4 characters -depending on how you want to represent them size changes slightly- which is (at minimum) 20 bytes while in binary format it would take 8 bytes.
How do I convert a binary file to a text file? ›
Here are some ways to convert a binary file to text:
- Use the nfacmd.sh command: Use the command /infacmd.sh ConvertLogFile -in /unix path/wf_name. ...
- Use an online converter: Use a free online converter like Duplichecker.com or SEOMagnifier to convert binary to text.
For example, only Microsoft Word and certain other word processing programs can interpret the formatting information in a Word document. Executable files, compiled programs, SAS and SPSS system files, spreadsheets, compressed files, and graphic (image) files are all examples of binary files.
What can I do with a binary file? ›
Binary file formats are most useful for storing raw data that isn't intended to be interpreted by humans. This includes things like bitmaps, audio files, and video streams.
What is the difference between binary file and text file in Java? ›
There are two types of files in Java - text files and binary files. Files provide both sequential and random access. A text file is processed as a sequence of characters. A binary file is processed as a sequence of bytes.
How is data stored in a binary file? ›
Structure. Binary files are usually thought of as being a sequence of bytes, which means the binary digits (bits) are grouped in eights. Binary files typically contain bytes that are intended to be interpreted as something other than text characters.
What does binary data look like? ›
Binary data is data whose unit can take on only two possible states. These are often labelled as 0 and 1 in accordance with the binary numeral system and Boolean algebra.
Why use binary files? ›
1 Binary file structure. One of the advantages of binary files is that they are more efficient. In terms of memory, storing values using numeric formats such as IEEE 754, rather than as text characters, tends to use less memory. In addition, binary formats also offer advantages in terms of speed of access.
One of the main advantages of using text files is that they are simple and easy to read and edit. They can be opened and edited using a simple text editor, such as notepad, and they can be easily transferred between different computer systems.
Which of these is a main difference between text and binary files? ›
At the user level, the primary difference between binary and text files is text files store data in human-readable format, and binary files are stored in binary form, i.e., 0s and 1s. If you open a text file, you can see data that an average human can understand.
How do I create a binary file from an existing text file? ›
Until the end of the text file is reached perform the following steps:
- Read a line from the input text file, into 3 variables using fscanf().
- The structure variable is set to values for elements(to write the structure variable into the output file.
- Write that structure variable to the output binary file using fwrite().
After opening the binary file in binary mode, we can use the read() method to read its content into a variable. The” read()” method will return a sequence of bytes, which represents the binary data. Once we have read the binary data into a variable, we can process it according to our specific requirements.
What does 10001 mean in binary? ›
And the binary number 10001 stands for 1×24+0×23+0×22+0×21+1×20=16+0+0+0+1=17 (written in decimal notation). You can convince yourself that a binary number only consists of the digits 0 or 1. When you write a number as a sum of consecutive powers of 2, no other coefficients are necessary.
Is PDF a text file or binary file? ›
PDF files are either 8-bit binary files or 7-bit ASCII text files (using ASCII-85 encoding). Every line in a PDF can contain up to 255 characters.
What is an example of a text file? ›
Common examples of text files include saved email messages, word processing documents and log files.
Is a word document a binary file? ›
Microsoft Word versions before Word 97 ("8.0") used a different format from the OLE and CFBF-based Microsoft Word 97 – 2003. In Microsoft Word 2007 and later, the binary file format was replaced as the default format by the Office Open XML format, though Microsoft Word can still produce DOC files.
What is the difference between opening a file in binary or text mode? ›
On some platforms, notably Windows and several others, opening a file in "text mode" has the specific effect of translating newline characters into carriage return/newline pairs. Opening a file in "binary mode" disables this character translation so that files can be processed exactly as they are stored.
