''' CS 1112 Spring 2020 In Class Review Session 04/22/2020 '''

''' Clockwise / Counterclockwise Rotation '''
# Please refer to the ImagingGuide picture I sent out (Nadia).

''' For understanding: '''
# Remember that when it comes to clockwise/counterclockwise rotation,
# x is basically the distance we go across and y is the distance we go down from the origin (0,0)
# x values go from 0 to the width - 1
# y values go from 0 to the height - 1
# When you get problems that ask you to manipulate the spot, think about how the nx relates to the ox
# by drawing it out and seeing how the spots translate over on the new image. I'd be happy to go over
# this Thursday as well.

''' Color Function: '''
# YOU WILL ONLY WORRY ABOUT COLOR FUNCTION SO THE SPOT STUFF YOU DON'T REALLY HAVE TO WORRY ABOUT.
# That will be filled in for you for dimensions and spots. You will have to worry about changing the color
# in the right way!
def color(opixel):
    r,g,b = opixel
    nr, ng, nb = ...
    return (nr,ng,nb)
# That's it. You just need to fill in line 21. :)

''' Dictionaries / Keys '''
# dictionaries are a collection of key/value mappings {k:v,k:v,k:v}
d1 = { 1:10, 10:100, 100:1000, 1000:0 }
print( d1.keys() ) # d1.keys() gives you all the keys in a dictionary.
print( d1.values() ) # d1.values() gives you all the values in a dictionary.

# Loop through a dictionary
for key in d1.keys(): # for key in d1 # Same thing!
    ...

# How do I get the value from a key in a dictionary?
# dictionary_name[key]        dictionary_name.get( key )
# Only if you know the          # Returns value if it's in the dictionary
# key is in the dictionary      # or None if it's not in the dictionary

# len(d1) -> number of mappings in d1 (dictionary) - A mapping is one k:v pair.
# KEYS are unique. VALUES can be repeated.
# Can do:
    # {1:'odd', 2:'even', 3:'odd', 4:'even'}
# Cannot have the same key have a bunch of values:
    # {1: 'odd', 1:'even'} -> PREVIOUS VALUE OF KEY IS REPLACED IF YOU REASSIGN IT
    # 1:'even' will be the mapping!

# You can map anything to anything.

''' Datasets: Rows and Columns '''

# A table/dataset is a list of lists.
dataset1 =  [[2, 4, 6], [8], [10, 12]]
#             0  1  2    0     0   1
#               0        1       2

# DATASET INDEXES:
# 1st row = dataset[0] = [2,4,6]
# 2nd value in 1st row = dataset[0][1] = 4

# for row in dataset:                   Access each smaller list in the dataset!
    # for cell/column in row:           Access each value in the smaller lists (rows)

# Each row is the smaller list
# Each value is the numbers in the rows
# Nested for loop allows you to loop through rows/columns
total = 0
for row in dataset1:
    for value in row:
        total = total + value
print( total )

total = 0
for row in dataset1:
    row_total = sum( row ) # Call sum( list ) on the smaller row (smaller list)
    total = total + row_total
print( total )

''' Floats '''
# Floats are just decimals. They are a type in Python.
# int is an integer. float is a decimal.
# We can cast numbers to a float using the float( x ) function
num1 = float(3)      # 3.0 (Integer to float)
num2 = float('3.25') # 3.25 (String to float)

print(num1)
print(num2)

# Use the int( x ) function to throw away the decimal part of a number.
# int(3.98237498235) -> 3 (not rounding! chops off decimal part!)
# Read the instructions on the exam and see if you're supposed to use integers / floats.

''' Local Variables '''
# Local variables are variables defined inside a function (not accessible everywhere / outside scope of function).
def quack():
    number_ducks_earned = 0  # number_ducks_earned is a local variable!
    return number_ducks_earned

# print(number_ducks_earned) # Notice how Python is like ??? What?? What's that??
                           # It's because that local variable only exists within the scope of the function!
                           # Not accessible everywhere throughout the program!

''' Optional Parameters '''
# Optional parameters allow you to have a way to specify default values for parameters if the user
# doesn't supply arguments for those parameters.
def function1( parameter1='hello', parameter2='world'):

    return parameter1 + " " + parameter2 # glues parameters together (concatenation)

# Arguments are passed in in the order of the parameters!
result1 = function1('CS','1112') # 'CS 1112' - parameter1 is 'CS' parameter2 is '1112'
result2 = function1( 'hi' )   # 'hi world' - 1 argument other one goes to default!
result3 = function1() # 'hello world' - both default parameters!
result4 = function1( parameter2='hi' ) # 'hello hi' - specify specific argument for parameter!

print(result1)
print(result2)
print(result3)
print(result4)

''' Function with no return statement '''
# EXAMPLE OF A FUNCTION WITH NO RETURN STATEMENT
# THAT MODIFIES THE ORIGINAL LIST (lists are mutable)

# You would get the def insert_value(x,i,v) - you would only write the function body.
# !!!!! You will get function DEFINITIONS AND TESTERS. Just fill in the function body!

def insert_value( x , i, v ): # Takes in a list modifies the list
                      # returns None
    x.insert(i, v) # Modify the original list x

# This function returns None by default (no explicit return statement)!

list1 = [1,2,3]
insert_value( list1, 2, 4) # We can call the function directly!
print( list1 )
# The original list (list1) was modified!