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Python Data Science Toolbox (Part 2)

Run the hidden code cell below to import the data used in this course.

1 hidden cell

Take Notes

Add notes about the concepts you've learned and code cells with code you want to keep.

Add your notes here

# Add your code snippets here

Explore Datasets

Use the DataFrames imported in the first cell to explore the data and practice your skills!

  • Create a zip object containing the CountryName and CountryCode columns in world_ind. Unpack the resulting zip object and print the tuple values.
  • Use a list comprehension to extract the first 25 characters of the text column of the tweets DataFrame provided that the tweet is not a retweet (i.e., starts with "RT").
  • Create an iterable reader object so that you can use next() to read datasets/world_ind_pop_data.csv in chunks of 20.
# 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)
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# 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)
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# 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 person in flash:
    print(person)


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

# Print each item from the iterator
print(next(superhero))
print(next(superhero))
print(next(superhero))
print(next(superhero))
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# 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))
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# 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)
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# 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)
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# 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 mutant_zip:
    print(value1, value2, value3)
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# 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)
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# Create list comprehension: squares
squares = [i**2 for i in range(0,10)]
print(squares)
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