1. IST256 : Applications Programming for Information Systems
Dictionaries

2. Agenda Connection Activity Teaching: Practice Activity Dictionaries
Word Counts

3. Connect Activity 1-800 How’s My Teaching?
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4. Dictionaries
The dict type is designed to store key-value pairs. In Python this is known as a mapping type.
font={‘Name’:’Arial’,’Size’: 8}
Python dicts are mutable which means you can change the values.
Dictionary values are accessed by key not by index.
font[‘Name’] = “Courier”

5. Watch Me Code Dictionary Basics: Create a dictionary Update its value
Print it out
Short and sweet demo

6. Dictionary Functions
Like str and list, the dict type has its own set of built- in functions.
ping-types-dict

7. Watch Me Code Dictionary Functions: KeyError get() values() keys()
Short and sweet demo

8. 90 Second Challenge Given: x = {"y":"w", "t":5, "q":True}
What is X["y"] ?
What is X["w"] ?
What is X["q"] ?
What is X.get("w") ?
What is X.values() ?

9. Help me Code
List of Dictionary == In-Memory Database!!! Write a program to read customer information from a file (GitHub) and outputs the names and total purchased of NY customers only.
Similar to this:
file = '/pub/datasets/grades/fall2015.tsv'
grades = list()
with open(file) as inp:
for line in inp:
values = line.split()
vald = { 'course': values[2], 'credits': values[3], 'grade' : values[4] }
grades.append(vald)

10. Now You Code Statistical Word Counts
Write a program to read text from a file, and print out a distribution of words and their counts. Example: “This is what this is” would output: this:2 is:2 what:1
Suggested Approach
Make a text file a paragraph of text in it. Or copy the text from the web.
Write the program to read the file and print a line at a time
Modify the program to split the line into words and print a word at a time.
Modify the program to add the words in a dictionary using the word as they key and the count as the value.
After the dictionary is created, write code to print out the dictionary.