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@@ -1,105 +1,144 @@ -# Sorting algorithms +Sorting algorithms +================== Gettting the hang out of (sorting) algorithms. -Hosted on [GitHub Pages] at https://egor-tensin.github.io/sorting-algorithms/. +The corresponding blog is hosted on [GitHub Pages] at +https://egor-tensin.github.io/sorting-algorithms/. [GitHub Pages]: https://pages.github.com/ -## Algorithms +Prerequisites +------------- -Each of the implemented sorting algorithms resides in a separate Python module -(in the `algorithms.impl` package). -Currently the following algorithms are implemented: +Python 3.4 or higher is required. +Additionally, the excellent [matplotlib] library is required for plotting. +The versions the author is using are listed below. -* bubble sort (`bubble_sort.py`), -* heapsort (`heapsort.py`), -* insertion sort (`insertion_sort.py`), -* merge sort (`merge_sort.py`), -* quicksort (`quicksort.py`), -* selection sort (`selection_sort.py`), -* calculating the median of a list (`median.py`). +Software | Version +------------ | ------- +Python | 3.5.1 +[matplotlib] | 1.5.1 -### Testing - -You can test each of the algorithms above by passing a sequence of integer -numbers to the corresponding script: +Algorithms +---------- - > heapsort.py 5 3 4 1 2 - [1, 2, 3, 4, 5] +Each of the implemented sorting algorithms resides in a separate Python module +(in the `algorithms.impl` package). +The implemented algorithms are listed below. + +Module name | Description +---------------- | -------------- +`bubble_sort` | Bubble sort +`heapsort` | Heapsort +`insertion_sort` | Insertion sort +`median` | Median value +`merge_sort` | Merge sort +`quicksort` | Quicksort +`selection_sort` | Selection sort Some algorithms actually come in different variants. For example, the implementation of quicksort includes a number of versions depending on how the pivot element is chosen, be it the first, the second, the middle, the last or a random element of the sequence. - > quicksort.py 5 3 4 1 2 - [1, 2, 3, 4, 5] - [1, 2, 3, 4, 5] - [1, 2, 3, 4, 5] - [1, 2, 3, 4, 5] - [1, 2, 3, 4, 5] +Testing +------- -You can use `test.py` to quickly generate an input list of some kind and +You can test each of the algorithms above by passing a sequence of integer +numbers to the corresponding script. +Notice that you must invoke the scripts from the top-level directory using +`python -m`. +For example: + +``` +> python -m algorithms.impl.heapsort 5 3 4 1 2 +[1, 2, 3, 4, 5] +``` + +``` +> python -m algorithms.impl.quicksort 5 3 4 1 2 +[1, 2, 3, 4, 5] +[1, 2, 3, 4, 5] +[1, 2, 3, 4, 5] +[1, 2, 3, 4, 5] +[1, 2, 3, 4, 5] +``` + +You can use "test.py" to quickly generate an input list of some kind and display the result of executing one of the implemented algorithms. Consult the output of `test.py --help` to learn how to use the script. A few usage examples are listed below. - > test.py -l quicksort_random -i ascending -n 10 - [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] +``` +> test.py --input best --length 1000 median_heaps +499.5 +``` - > test.py --algorithm median_heaps --order random --length 100 - 49.5 +``` +> test.py --input worst --length 10 quicksort_random +[0, 1, 2, 3, 4, 5, 6, 7, 8, 9] +``` -## Plots +Plotting +-------- The goals of this "project" include a) familiarizing myself with a few sorting algorithms by examining their (possibly, simplified) implementations and b) studying the way algorithm's running time changes in relation to the length of its input (a.k.a. identifying its time complexity). -A simple way to visualize the way algorithm's running time changes would be to -make appropriate measurements and plot them on a nice graph. +A simple way to visualize the way algorithm's running time changes is to make +appropriate measurements and plot them on a nice graph. The results of course are highly dependent on the hardware used, while the graph's look depends on the software used for rendering. I've made the measurements for each of the implemented algorithms and put the plots to the "plots/" directory. -Both the hardware & the software versions that were used to produce the plots -are listed below. +Both the hardware & the software that were used to produce the plots are listed +below. -| Component | Version | -| ------------ | --------------------- | -| CPU | [Intel Core i3-5005U] | -| OS | Windows 8.1 | -| Python | 3.5.1 | -| [matplotlib] | 1.5.1 | +Component | Version +------------ | --------------------- +CPU | [Intel Core i3-5005U] +OS | Windows 8.1 +Python | 3.5.1 +[matplotlib] | 1.5.1 [Intel Core i3-5005U]: http://ark.intel.com/products/84695/Intel-Core-i3-5005U-Processor-3M-Cache-2_00-GHz [matplotlib]: http://matplotlib.org/ -Each of the implemented algorithms was provided with three input sequences: +Each of the implemented sorting algorithms was provided with three input +sequences: + * a list of *n* consecutive numbers sorted in ascending order, * ... in descending order, * ... in random order. -You can generate similar plots using `plot.py`. -Consult the output of `plot.py -h` to learn how to use the script. +You can generate similar plots using "plot.py". +Consult the output of `plot.py --help` to learn how to use the script. A few usage examples are listed below. - > plot.py --algorithm merge_sort --min 0 --max 200 --order ascending -iterations 1000 +``` +> plot.py merge_sort --min 0 --max 200 --input best --iterations 1000 +``` - > plot.py -l median_sort_first -a 0 -b 200 -i random -r 100 -o median_sort_first.png +``` +> plot.py median_sorting --min 0 --max 200 --input average --iterations 100 --output median_sorting.png +``` If you're having problems using the script (like having excessive noise in the -measurement results), try minimizing background activity of the OS and running +measurement results), try minimizing background activity of your OS and applications. -For example, on Windows 8.1 I managed to produce some very nice plots by -booting into Safe Mode and running the script with a higher priority while -also setting its CPU affinity: +For example, on Windows 8.1 I got very reasonable plots after booting into Safe +Mode and running the script with a higher priority while also setting its CPU +affinity: - > start /affinity 1 /realtime plot.py ... +``` +> start /affinity 1 /realtime plot.py ... +``` -## License +License +------- This project, including all of the files and their contents, is licensed under the terms of the MIT License. |