From 94d275111f1186159fa592d86c47bfc9defbb536 Mon Sep 17 00:00:00 2001
From: Neil Smith <neil.git@njae.me.uk>
Date: Sun, 1 Jun 2014 12:25:24 +0100
Subject: [PATCH] Finished keyword breaking, started word segmentation
---
slides/keyword-break.html | 39 +++++++++++++++--
slides/word-segmentation.html | 81 +++++++++++++++++++++++++++++++++++
2 files changed, 116 insertions(+), 4 deletions(-)
create mode 100644 slides/word-segmentation.html
diff --git a/slides/keyword-break.html b/slides/keyword-break.html
index b3c0a2c..46dded5 100644
--- a/slides/keyword-break.html
+++ b/slides/keyword-break.html
@@ -51,7 +51,7 @@ a | b | c | d | e | f | g | h | i | j | k | l | m | n | o | p | q | r | s | t |
--|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|--
k | e | y | w | o | r | d | a | b | c | f | g | h | i | j | l | m | n | p | q | s | t | u | v | x | z
-----
+---
# Duplicate and extend your `affine_break()` function
@@ -85,11 +85,11 @@ But before we get there, a couple of diversions...
---
-# `map()`
+# map()
A common task is to apply a function to each item in a sequence, returning a sequence of the results.
-```python```
+```python
def double(x):
return x * 2
@@ -107,11 +107,13 @@ How can we use this for keyword cipher breaking?
Define a function that takes a possible key (keyword and cipher type) and returns the key and its fitness.
+* (Also pass in the message and the fitness function)
+
Use `map()` and `max()` to find the best key
---
-# `print()`
+# Arity of print()
How many arguments does this take?
@@ -143,6 +145,35 @@ First number goes in `x`, remaining go in the tuple `xs`
What does `Pool.starmap()` do?
+---
+
+```python
+from multiprocessing import Pool
+
+def keyword_break_mp(message, wordlist=keywords, fitness=Pletters, chunksize=500):
+ helper_args = [??? for word in wordlist] # One tuple for each possible key
+ with Pool() as pool:
+ breaks = pool.starmap(keyword_break_worker, helper_args, chunksize)
+ return max(breaks, key=lambda k: k[1])
+
+def keyword_break_worker(???):
+ ???
+ return (key, fitness)
+```
+
+* Gotcha: the function in `Pool.starmap()` must be defined at the top level
+ * This is definitely a "feature"
+
+---
+
+# Performance and chunksize
+
+Try the multiprocessing keyword break. Is it using all the resources?
+
+Setting `chunksize` is an art.
+
+## Map-reduce as a general pattern for multiprocessing
+
</textarea>
<script src="http://gnab.github.io/remark/downloads/remark-0.6.0.min.js" type="text/javascript">
</script>
diff --git a/slides/word-segmentation.html b/slides/word-segmentation.html
new file mode 100644
index 0000000..6eb88e3
--- /dev/null
+++ b/slides/word-segmentation.html
@@ -0,0 +1,81 @@
+<!DOCTYPE html>
+<html>
+ <head>
+ <title>Affine ciphers</title>
+ <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
+ <style type="text/css">
+ /* Slideshow styles */
+ body {
+ font-size: 20px;
+ }
+ h1, h2, h3 {
+ font-weight: 400;
+ margin-bottom: 0;
+ }
+ h1 { font-size: 3em; }
+ h2 { font-size: 2em; }
+ h3 { font-size: 1.6em; }
+ a, a > code {
+ text-decoration: none;
+ }
+ code {
+ -moz-border-radius: 5px;
+ -web-border-radius: 5px;
+ background: #e7e8e2;
+ border-radius: 5px;
+ font-size: 16px;
+ }
+ .plaintext {
+ background: #272822;
+ color: #80ff80;
+ text-shadow: 0 0 20px #333;
+ padding: 2px 5px;
+ }
+ .ciphertext {
+ background: #272822;
+ color: #ff6666;
+ text-shadow: 0 0 20px #333;
+ padding: 2px 5px;
+ }
+ .float-right {
+ float: right;
+ }
+ </style>
+ </head>
+ <body>
+ <textarea id="source">
+
+# Word segmentation
+
+a | b | c | d | e | f | g | h | i | j | k | l | m | n | o | p | q | r | s | t | u | v | w | x | y | z
+--|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|--
+k | e | y | w | o | r | d | a | b | c | f | g | h | i | j | l | m | n | p | q | s | t | u | v | x | z
+
+----
+
+
+ </textarea>
+ <script src="http://gnab.github.io/remark/downloads/remark-0.6.0.min.js" type="text/javascript">
+ </script>
+
+ <script type="text/javascript"
+ src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML&delayStartupUntil=configured"></script>
+
+ <script type="text/javascript">
+ var slideshow = remark.create({ ratio: "16:9" });
+
+ // Setup MathJax
+ MathJax.Hub.Config({
+ tex2jax: {
+ skipTags: ['script', 'noscript', 'style', 'textarea', 'pre']
+ }
+ });
+ MathJax.Hub.Queue(function() {
+ $(MathJax.Hub.getAllJax()).map(function(index, elem) {
+ return(elem.SourceElement());
+ }).parent().addClass('has-jax');
+ });
+ MathJax.Hub.Configured();
+ </script>
+ </body>
+</html>
--
2.43.0