c# barcode generator library free Note When developing software it s always worth considering the likelihood of the software being in Font

Encoder Data Matrix in Font Note When developing software it s always worth considering the likelihood of the software being

extended or tweaked in the future and planning ahead for the possibility. Many development bottlenecks have occurred when systems were designed too rigidly to cope with changing circumstances!

Most written material, including this very book, contains a high number of words that, although providing context and structure, are not directly useful or interesting. In the last sentence, the words that, and, are, and or are not of particular interest, even if the sentence would make less sense without them. These words are typically called stop words, and are often ignored by computer systems whose job is to analyze and search through text, because they aren t words most people are likely to be searching for (as opposed to nouns, for example). Google is a perfect example of this, as it doesn t want to have to store information that takes up space and that s generally irrelevant to searches.

Note For more information about stop words, including links to complete lists, visit http://en.wikipedia.

It could be assumed that more interesting text, or text by a more proficient author, might have a lower percentage of stop words and a higher percentage of useful or interesting words. You can easily extend your application to work out the percentage of non stop words in the supplied text. The first step is to build up a list of stop words. There are hundreds of possible stop words, but you ll start with just a handful. Let s create an array to hold them:

stop_words = %w{the a by on for of are with just but and to the my I has some in}

= ['a', 'b', 'c']. However, like many languages, Ruby has a shortcut that builds arrays quickly with string-separated text. This segment can be shorted to the equivalent x = %w{a b c}, as demonstrated in the preceding stop word code.

For demonstration purposes, let s write a small, separate program to test the concept:

text = %q{Los Angeles has some of the nicest weather in the country.} stop_words = %w{the a by on for of are with just but and to the my I has some} words = text.scan(/\w+/) key_words = words.select { |word| !stop_words.include (word) } puts key_words.join(' ')

When you run this code, you get the following result:

Cool, right First you put some text into the program, then the list of stop words. Next you get all the words from text into an array called words. Then you get to the magic:

key_words = words.select { |word| !stop_words.include (word) }

This line first takes your array of words, words, and calls the select method with a block of code to process for each word (like the iterators you played with in 3). The select method is a method available to all arrays and hashes that returns the elements of that array or hash that match the expression in the code block. In this case, the code in the code block takes each word via the variable word, and asks the stop_words array whether it includes any elements equal to word. This is what stop_words.include (word) does. The exclamation mark (!) before the expression negates the expression (an exclamation mark negates any Ruby expression). The reason for this is you don t want to select words that are in the stop_words array. You want to select words that aren t. In closing, then, you select all elements of words that are not included in the stop_words array and assign them to key_words. Don t read on until that makes sense, as this type of single-line construction is common in Ruby programming. After that, working out the percentage of non stop words to all words uses some basic arithmetic: