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Data Manipulation with pandas

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

# Import the course packages
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt

# Import the four datasets
avocado = pd.read_csv("datasets/avocado.csv")
homelessness = pd.read_csv("datasets/homelessness.csv")
temperatures = pd.read_csv("datasets/temperatures.csv")
walmart = pd.read_csv("datasets/walmart.csv")

Take Notes

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

Add your notes here

# Sort homelessness by region, then descending family members
homelessness_reg_fam = homelessness.sort_values(["region","family_members"],ascending=[True,False])

# Print the top few rows
print(homelessness_reg_fam.head())
# Add your code snippets here

Explore Datasets

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

  • Print the highest weekly sales for each department in the walmart DataFrame. Limit your results to the top five departments, in descending order. If you're stuck, try reviewing this video.
  • What was the total nb_sold of organic avocados in 2017 in the avocado DataFrame? If you're stuck, try reviewing this video.
  • Create a bar plot of the total number of homeless people by region in the homelessness DataFrame. Order the bars in descending order. Bonus: create a horizontal bar chart. If you're stuck, try reviewing this video.
  • Create a line plot with two lines representing the temperatures in Toronto and Rome. Make sure to properly label your plot. Bonus: add a legend for the two lines. If you're stuck, try reviewing this video.

Subsetting rows A large part of data science is about finding which bits of your dataset are interesting. One of the simplest techniques for this is to find a subset of rows that match some criteria. This is sometimes known as filtering rows or selecting rows.

There are many ways to subset a DataFrame, perhaps the most common is to use relational operators to return True or False for each row, then pass that inside square brackets.

dogs[dogs["height_cm"] > 60] dogs[dogs["color"] == "tan"] You can filter for multiple conditions at once by using the "bitwise and" operator, &.

dogs[(dogs["height_cm"] > 60) & (dogs["color"] == "tan")] homelessness is available and pandas is loaded as pd.

# Filter for rows where family_members is less than 1000 
# and region is Pacific
fam_lt_1k_pac = homelessness[(homelessness["family_members"]>1000)&(homelessness["region"]=="Pacific")]

# See the result
print(fam_lt_1k_pac)
# Subset for rows in South Atlantic or Mid-Atlantic regions


south_mid_atlantic = homelessness[(homelessness["region"]=="South Atlantic")|(homelessness["region"]=="Mid-Atlantic")]

# See the result
print(south_mid_atlantic)
# The Mojave Desert states
canu = ["California", "Arizona", "Nevada", "Utah"]

# Filter for rows in the Mojave Desert states
mojave_homelessness = homelessness[homelessness["state"].isin(canu)]

# See the result
print(mojave_homelessness)
# Create indiv_per_10k col as homeless individuals per 10k state pop
homelessness["indiv_per_10k"] = 10000 * homelessness["individuals"] / homelessness["state_pop"] 

# Subset rows for indiv_per_10k greater than 20
high_homelessness = homelessness[homelessness["indiv_per_10k"] > 20]

# Sort high_homelessness by descending indiv_per_10k
high_homelessness_srt = high_homelessness.sort_values("indiv_per_10k", ascending=False)

# From high_homelessness_srt, select the state and indiv_per_10k cols
result = high_homelessness_srt[["state","indiv_per_10k"]]

# See the result
print(result)