13.3. File Modes
Default mode is read text mode (
rt)Text - easy to read and write
Binary - Fast and efficient
Read - Get data from file
Write - Save data to file (overwrite existing data)
Append - Add line to file
Update - Read and Write (rarely used)
By type:
Text - easy to read and write
Binary - Fast and efficient
By operation:
Read - Get data from file
Write - Save data to file (overwrite existing data)
Append - Add line to file
Update - Read and Write (rarely used)
If mode is not specified it will read in text mode (mode='r')
13.3.1. Example
If mode is not specified it will read in text mode (
mode='r')
>>> open('/tmp/myfile.txt')
<_io.TextIOWrapper name='/tmp/myfile.txt' mode='r' encoding='UTF-8'>
13.3.2. Modes
r - For reading – The file pointer is placed at the beginning of the file. This is the default mode.
r+ - Opens a file for both reading and writing. The file pointer will be at the beginning of the file.
w - Opens a file for writing only. Overwrites the file if the file exists. If the file does not exist, creates a new file for writing.
w+ - Opens a file for both writing and reading. Overwrites the existing file if the file exists. If the file does not exist, it creates a new file for reading and writing.
rb - Opens a file for reading only in binary format. The file pointer is placed at the beginning of the file.
rb+ - Opens a file for both reading and writing in binary format.
wb+ - Opens a file for both writing and reading in binary format. Overwrites the existing file if the file exists. If the file does not exist, it creates a new file for reading and writing.
a - Opens a file for appending. The file pointer is at the end of the file if the file exists. That is, the file is in the append mode. If the file does not exist, it creates a new file for writing.
ab - Opens a file for appending in binary format. The file pointer is at the end of the file if the file exists. That is, the file is in the append mode. If the file does not exist, it creates a new file for writing.
a+ - Opens a file for both appending and reading. The file pointer is at the end of the file if the file exists. The file opens in the append mode. If the file does not exist, it creates a new file for reading and writing.
ab+ - Opens a file for both appending and reading in binary format. The file pointer is at the end of the file if the file exists. The file opens in the append mode. If the file does not exist, it creates a new file for reading and writing.
x - Open for exclusive creation, failing if the file already exists (Python 3)
Source: [1]
13.3.3. Short Notation
Most commonly used
By default text mode is used
mode='r'- read in text mode (default)mode='w'- write in text modemode='a'- append in text mode
>>> open('/tmp/myfile.txt', mode='r')
<_io.TextIOWrapper name='/tmp/myfile.txt' mode='r' encoding='UTF-8'>
>>> open('/tmp/myfile.txt', mode='w')
<_io.TextIOWrapper name='/tmp/myfile.txt' mode='w' encoding='UTF-8'>
>>> open('/tmp/myfile.txt', mode='a')
<_io.TextIOWrapper name='/tmp/myfile.txt' mode='a' encoding='UTF-8'>
13.3.4. Text Mode
Text - easy to read and write
mode='rt'- read in text modemode='wt'- write in text modemode='at'- append in text mode
>>> open('/tmp/myfile.txt', mode='rt')
<_io.TextIOWrapper name='/tmp/myfile.txt' mode='rt' encoding='UTF-8'>
>>> open('/tmp/myfile.txt', mode='wt')
<_io.TextIOWrapper name='/tmp/myfile.txt' mode='wt' encoding='UTF-8'>
>>> open('/tmp/myfile.txt', mode='at')
<_io.TextIOWrapper name='/tmp/myfile.txt' mode='at' encoding='UTF-8'>
13.3.5. Binary Mode
Binary - Fast and efficient
mode='rb'- read in binary modemode='wb'- write in binary modemode='ab'- append in binary mode
>>> open('/tmp/myfile.txt', mode='rb')
<_io.BufferedReader name='/tmp/myfile.txt'>
>>> open('/tmp/myfile.txt', mode='wb')
<_io.BufferedWriter name='/tmp/myfile.txt'>
>>> open('/tmp/myfile.txt', mode='ab')
<_io.BufferedWriter name='/tmp/myfile.txt'>
13.3.6. Update Mode
Reading and Writing
Text mode is used if not specified otherwise
mode='r+'- read in text modemode='w+'- write in text modemode='a+'- append in text modemode='rt+'- update in text modemode='wt+'- update in text modemode='at+'- update in text modemode='rb+'- update in binary modemode='wb+'- update in binary modemode='ab+'- update in binary mode
>>> open('/tmp/myfile.txt', mode='r+')
<_io.TextIOWrapper name='/tmp/myfile.txt' mode='r+' encoding='UTF-8'>
>>>
>>> open('/tmp/myfile.txt', mode='w+')
<_io.TextIOWrapper name='/tmp/myfile.txt' mode='w+' encoding='UTF-8'>
>>>
>>> open('/tmp/myfile.txt', mode='a+')
<_io.TextIOWrapper name='/tmp/myfile.txt' mode='a+' encoding='UTF-8'>
>>> open('/tmp/myfile.txt', mode='rt+')
<_io.TextIOWrapper name='/tmp/myfile.txt' mode='rt+' encoding='UTF-8'>
>>>
>>> open('/tmp/myfile.txt', mode='wt+')
<_io.TextIOWrapper name='/tmp/myfile.txt' mode='wt+' encoding='UTF-8'>
>>>
>>> open('/tmp/myfile.txt', mode='at+')
<_io.TextIOWrapper name='/tmp/myfile.txt' mode='at+' encoding='UTF-8'>
>>> open('/tmp/myfile.txt', mode='rb+')
<_io.BufferedRandom name='/tmp/myfile.txt'>
>>>
>>> open('/tmp/myfile.txt', mode='wb+')
<_io.BufferedRandom name='/tmp/myfile.txt'>
>>>
>>> open('/tmp/myfile.txt', mode='ab+')
<_io.BufferedRandom name='/tmp/myfile.txt'>
13.3.7. Recap
Most common (90% of cases):
mode='r'- read in text mode (default)
mode='w'- write in text mode
mode='a'- append in text mode
Text Mode:
mode='rt'- read in text mode
mode='wt'- write in text mode
mode='at'- append in text mode
Binary Mode:
mode='rb'- read in binary mode
mode='wb'- write in binary mode
mode='ab'- append in binary mode
Update (rarely used):
mode='rb+'- update in binary mode
mode='wb+'- update in binary mode
mode='ab+'- update in binary mode
mode='r+'- read in text mode
mode='w+'- write in text mode
mode='a+'- append in text mode
If mode is not specified it will read in text mode (
mode='rt')