Mood Analysis: Hash Practice

Let's practice interacting with Hashes (key-value pairings) by writing a program that creates hashes, stores data in hashes, retrieves data from hashes, and prints the contents of a hash.

mood-analysis.rb

Take a look at mood-analysis.rb.

What's Happening?

Explain what is happening on each of the following lines in the code.

Line #	What's happening?
1	Declaring constant variable
2	Declaring happy key-value pair
3	Declaring sad key-value pair
6	Declaring method
7-8	Declaring variables
9	Making words lowercase
10	Making string into array of words and looping through each word
11	Checking happy key in FEELINGS for the word
12	Add 1 to happy if word is in happy value array
13	Checking sad key in FEELINGS for the word
14	Add 1 to sad if word is in sad value array
17-19	Return appropriate smiley based on happiness/sadness values

Data Types

What's the Data Type of the following?

Code	Data Type
FEELINGS	Hash
:sad	Symbol
happy	Fixnum
words	String
words.split(" ")	Array
FEELINGS[:sad]	Array
FEELINGS[:happy].include?	Boolean
analyze_mood(text)	String

Explaining the Code

Question	Answer
Why do we need line 9?	Lines 11 and 13 are case sensitive
What is the relationship between words and word (line 10)?	words is a string and word is an element of an array
Why doesn't line 19 have an associated if/condition?	It is essentially the else statement.
What is the relationship between text[0], text[1], and words?	words is a parameter, text[0] and text[1] are arguments.

Assignment: Requirements

1. Replace lines 31 and 32 and write a loop to print out each day and the emoticon that is associated by analyzing the mood of that day.

Your result will look like:

03/01  :-(
03/13  :-|
...

think: Why does 03/13 come out as neutral when it should be happy? How could we fix this?

Both happy and sad values are 0 because each happy and sad word has punctuation attached so the words aren't matching during the .include method. This could be fixed by looping each word through a method that strips punctuation.

2. To make the results a little more accurate, let's write and utilize a method called strip_punctuation to strip out the punctuation that affects the results. Namely, remove exclamation marks (!), periods (.), commas (,), and hashtags (#).

Your method should take a string as an argument and return the string without the above mentioned punctuation.

After writing this method, our new result should be:

03/01  :-(
03/13  :-)
...

think: Where should we call strip_punctuation? Does it matter? Why? We should call strip_punctuation before running the analyze_mood. It matters because analyze_mood cannot produce an accurate result until the punctuation is removed.

3. Write a method called happy_days to determine how many logged entries it takes until there have been three :-) happy days.

Your output could be something like:

It takes 5 entries for 3 happy days to occur

think: What are you going to do if there aren't at least 3 happy days? Where do you need to handle that case?

4. Write a method called overall_mood to determine the most common mood across all logged entries.

Your output could be something like:

The most common mood is :-)

think: Should you use an array or a hash to solve this problem? Why?

think: What if we eventually want to add feelings to our analysis? Can we write this code in a way that will prevent us from having to re-write it later?