Chap 1 Using iterators in PythonLand.py

# Create a list of strings: flash
flash = ['jay garrick', 'barry allen', 'wally west', 'bart allen']

# Print each list item in flash using a for loop
for a in flash:
    print(a)


# Create an iterator for flash: superspeed
    superspeed=iter(flash)

# Print each item from the iterator
print(next(superspeed))
print(next(superspeed))
print(next(superspeed))
print(next(superspeed))
######

# Create an iterator for range(3): small_value
small_value = iter(range(3))

# Print the values in small_value
print(next(small_value))
print(next(small_value))
print(next(small_value))

# Loop over range(3) and print the values
for num in range(3):
    print(num)


# Create an iterator for range(10 ** 100): googol
googol = iter(range(10**100))

# Print the first 5 values from googol
print(next(googol))
print(next(googol))
print(next(googol))
print(next(googol))
print(next(googol))
######

# Create a range object: values
values = range(10,21)

# Print the range object
print(values)

# Create a list of integers: values_list
values_list = list(values)

# Print values_list
print(values_list)

# Get the sum of values: values_sum
values_sum = sum(values)

# Print values_sum
print(values_sum)
######

# Create a list of strings: mutants
mutants = ['charles xavier', 
            'bobby drake', 
            'kurt wagner', 
            'max eisenhardt', 
            'kitty pryde']

# Create a list of tuples: mutant_list
mutant_list = list(enumerate(mutants))

# Print the list of tuples
print(mutant_list)

# Unpack and print the tuple pairs
for index1,value1 in enumerate(mutants):
    print(index1, value1)

# Change the start index
for index2,value2 in enumerate(mutants,start=1):
    print(index2, value2)
######

# Create a list of tuples: mutant_data
mutant_data =list(zip(mutants,aliases,powers))

# Print the list of tuples
print(mutant_data)

# Create a zip object using the three lists: mutant_zip
mutant_zip = zip(mutants,aliases,powers)

# Print the zip object
print(mutant_zip)

# Unpack the zip object and print the tuple values
for value1, value2,value3 in zip(mutants,aliases,powers):
    print(value1, value2, value3)
######

# Create a zip object from mutants and powers: z1
z1 = zip(mutants,powers)

# Print the tuples in z1 by unpacking with *
print(*z1)

# Re-create a zip object from mutants and powers: z1
z1 = zip(mutants,powers)

# 'Unzip' the tuples in z1 by unpacking with * and zip(): result1, result2
result1, result2 = zip(*z1)

# Check if unpacked tuples are equivalent to original tuples
print(result1 == mutants)
print(result2 == powers)
######

# Initialize an empty dictionary: counts_dict
counts_dict={}

# Iterate over the file chunk by chunk
for chunk in pd.read_csv('tweets.csv',chunksize=10):

    # Iterate over the column in DataFrame
    for entry in chunk['lang']:
        if entry in counts_dict.keys():
            counts_dict[entry] += 1
        else:
            counts_dict[entry] = 1

# Print the populated dictionary
print(counts_dict)
######

# Define count_entries()
def count_entries(csv_file,c_size,colname):
    """Return a dictionary with counts of
    occurrences as value for each key."""
    
    # Initialize an empty dictionary: counts_dict
    counts_dict = {}

    # Iterate over the file chunk by chunk
    for chunk in pd.read_csv(csv_file,chunksize=c_size):

        # Iterate over the column in DataFrame
        for entry in chunk[colname]:
            if entry in counts_dict.keys():
                counts_dict[entry] += 1
            else:
                counts_dict[entry] = 1

    # Return counts_dict
    return counts_dict

# Call count_entries(): result_counts
result_counts = count_entries('tweets.csv',10,'lang')

# Print result_counts
print(result_counts)
######