random seed

kyclark · kyclark · commit 98add33fd549 · 2019-05-17T13:32:52.000-07:00
diff --git a/README.md b/README.md
@@ -4,6 +4,8 @@ I believe you can learn serious things through silly games.
 
 I'd like to make this into a book or something, similar to the Python bioinformatic/data science (https://github.com/kyclark/practical_python_for_data_science) repo. I think you will learn best by *doing*, so I think I will write this as a loose collection of exercises that spell out the skills I aim to teach with each exercise. I will create descriptions for each exercise with examples of how the program should work along with a test suite. You will need to write the program that satisfies the test suite.
 
+I think I'm going to present this differently from other material in that I won't necessarily show you beforehand what you need to write a program. I'll describe what the program should do and provide some discussion about how to write it. I'll also create an appendix with short example of how to do things like read/write from/to a file, process all the files in a directory, extract k-mers from a string, etc. I'll provide some building blocks, but I want you to figure out how to put the pieces together!
+
 # new_py.py
 
 I provide a program in the `bin` directory called `new_py.py` that will help you stub out new Python programs using the fabulous `argparse` module to parse the command line arguments and options for your programs. I highly recommend you start every new program with this. For example, if the `README` say "Write a Python program called `abc.py` that ...", then you should do this:
diff --git a/appendix/examples/random_seed.py b/appendix/examples/random_seed.py
@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+"""
+Author : kyclark
+Date   : 2019-05-17
+Purpose: Get/use a random seed from argparse
+"""
+
+import argparse
+import random
+import sys
+
+
+# --------------------------------------------------
+def get_args():
+    """get command-line arguments"""
+    parser = argparse.ArgumentParser(
+        description='Get/use a random seed from argparse',
+        formatter_class=argparse.ArgumentDefaultsHelpFormatter)
+
+    parser.add_argument('-s',
+                        '--seed',
+                        help='Random seed',
+                        metavar='int',
+                        type=int,
+                        default=None)
+
+    return parser.parse_args()
+
+
+# --------------------------------------------------
+def main():
+    """Make a jazz noise here"""
+    args = get_args()
+    random.seed(args.seed)
+
+    print('Random number is "{}"'.format(random.randint(1, 100)))
+
+
+# --------------------------------------------------
+if __name__ == '__main__':
+    main()
diff --git a/appendix/howto.md b/appendix/howto.md
@@ -164,6 +164,63 @@ bar
 baz
 ````
 
+## Accept/use a random seed argument
+
+Here is how I would define and use a random seed argument using `argparse`. If the `--seed` is defined with `default=None`, then you can pass it directly to `random.seed`. When it is defined by the user, it will be used; otherwise it is ignored.
+
+````
+$ cat -n random_seed.py
+     1	#!/usr/bin/env python3
+     2	"""
+     3	Author : kyclark
+     4	Date   : 2019-05-17
+     5	Purpose: Get/use a random seed from argparse
+     6	"""
+     7
+     8	import argparse
+     9	import random
+    10	import sys
+    11
+    12
+    13	# --------------------------------------------------
+    14	def get_args():
+    15	    """get command-line arguments"""
+    16	    parser = argparse.ArgumentParser(
+    17	        description='Get/use a random seed from argparse',
+    18	        formatter_class=argparse.ArgumentDefaultsHelpFormatter)
+    19
+    20	    parser.add_argument('-s',
+    21	                        '--seed',
+    22	                        help='Random seed',
+    23	                        metavar='int',
+    24	                        type=int,
+    25	                        default=None)
+    26
+    27	    return parser.parse_args()
+    28
+    29
+    30	# --------------------------------------------------
+    31	def main():
+    32	    """Make a jazz noise here"""
+    33	    args = get_args()
+    34	    random.seed(args.seed)
+    35
+    36	    print('Random number is "{}"'.format(random.randint(1, 100)))
+    37
+    38
+    39	# --------------------------------------------------
+    40	if __name__ == '__main__':
+    41	    main()
+$ ./random_seed.py
+Random number is "31"
+$ ./random_seed.py
+Random number is "35"
+$ ./random_seed.py -s 1
+Random number is "18"
+$ ./random_seed.py -s 1
+Random number is "18"
+````
+
 ## Test if an argument is a directory and list the contents
 
 ````
diff --git a/insult_generator/insult.py b/insult_generator/insult.py
