To improve the speed of code execution for intensive I / O tasks, languages have different input and output procedures.
Consider the question of finding a sum N numbers entered by the user.
Enter the number N.
Enter the N numbers, separated by one space per line.
Input: 5 1 2 3 4 5 Output: 15
Various Python solutions for the above problem:
Normal Python method: (Python 2.7)
1. raw_input () takes an optional prompt argument. It also removes the trailing newline character from the returned string.
2. print — it’s just a thin wrapper that formats the input (a space between arguments and a newline at the end) and calls the write function on the given object.
Slightly faster method using inline stdin, stdout: (Python 2.7)
1. sys.stdin, with another th side is File Object . This is similar to creating any other file object that you can create to read input from a file. In this case, the file will be the standard input buffer.
2. stdout.write (& # 39; D / n & # 39;) is faster than printing & # 39; D & # 39; .
3. It’s even faster to write everything once with stdout.write ("". Join (list-compceptionsion)), but this makes memory usage dependent on the size of the input.
The difference is time:
Timing summary (100k lines each)
Print: 6.040 s
Write to file: 0.122 s
Print with Stdout: 0.121 s
Add a buffered io pipe: (Python 2.7)
1. Simple add buffered th I / O code before the submit code to speed up the output.
2. The advantage of io.BytesIO objects is that they implement a common interface (commonly referred to as a "file" object). BytesIO objects have an internal pointer, and for each call to read (n), the pointer is advanced.
3. The atexit module provides a simple interface for registering functions that are called when the program is closed normally. The sys module also provides a sys.exitfunc hook, but only one function can be registered there. The atexit registry can be used by multiple modules and libraries at the same time.
Usually, when processing a lot of data, the usual method cannot be completed in a timely manner. Method 2 helps to maintain a large amount of I / O data. Method 3 is the fastest. Typically, input data files larger than 2 or 3 MB are processed using methods 2 and 3.
This article courtesy of Shubham Saxena . If you are as Python.Engineering and would like to contribute, you can also write an article using contribute.python.engineering or by posting an article contribute @ python.engineering. See my article appearing on the Python.Engineering homepage and help other geeks.
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