Dropping Bars

Introduction to Data Visualization with Julia

Gustavo Vieira Suñe

Data Analyst

Bar charts

A bar chart displaying the average prices of different products in India.

Bar charts vs histograms

Distributions of numerical data

A histogram displaying the distribution of onion and wheat prices.

Comparison of categories

A bar chart displaying the average prices of different products in India.

Our dataset

Date	State	Centre	Product	Price
APR-2001	Andhra Pradesh	Chittoor	Bathing Soap	10.0
APR-2001	Andhra Pradesh	Chittoor	Ink	10.0
...	...	...	...	...
SEP-2016	Bihar	Patna	Paper	38.0
SEP-2016	Bihar	Patna	Toothpaste	50.0

Mean prices (using Statistics)

# Group by each product
grouped = groupby(product, :Product)

# Calculate average prices
mean_prices = combine(
    grouped,
    :Price => mean
)

# Sort from higest to lowest
sorted_mean_prices = sort(
    mean_prices,
    :Price_mean,
    rev=true
)

Creating bar charts

# Create bar chart
bar(
    # Categories in x-axis
    sorted_mean_prices.Product,
    # Values in y-axis
    sorted_mean_prices.Price_mean,

    # Set bar width
    bar_width=0.5

    label=false,
    color=:royalblue1,
 )
title!("Product Prices in India")
ylabel!("Average Price (Rupees)")

A bar chart displaying the average prices of different products in India.

Horizontal bar charts

# Create bar chart
bar(
    # Values in the y-axis
    sorted_mean_prices.Product,
    # Values in x-axis
    sorted_mean_prices.Price_mean,

    # Set orientation to horizontal
    permute=(:x, :y),

    label=false,
    color=:royalblue1,
)
title!("Product Prices in India")
xlabel!("Average Price (Rupees)")

A horizontal bar chart displaying the average prices of different products in India.

Products by state

Filter for selected states

filtered_product = filter(
    row -> row.State in ["Maharashtra", "Goa", "Gujarat"],
    product)

Average prices of each product by state

# Group by state and product
filtered_grouped = groupby(filtered_product, [:State, :Product])

# Calculate average prices
filtered_mean_prices = combine(
    filtered_grouped, :Price => mean
)

Grouped bar charts

# Create grouped bar chart
groupedbar(
    # Categories in x-axis
    filtered_mean_prices.Commodity,
    # Values in y-axis
    filtered_mean_prices.Price_mean,

    # Define groups
    group=filtered_mean_prices.State,

    color=[:teal :yellow2 :tomato3]
)
title!("Prices in India by State")
ylabel!("Average Price (Rupees)")

A grouped bar chart displaying the prices of some products in India grouped by state, with bars shown side-by-side.

Stack the bars

# Create grouped bar chart
groupedbar(
    # Categories in x-axis
    filtered_mean_prices.Commodity,
    # Values in y-axis
    filtered_mean_prices.Price_mean, 
    # Define groups
    group=filtered_mean_prices.State,
    color=[:teal :snow2 :tomato3],

    # Stack the bars
    bar_position=:stack

)
title!("Product Prices in India by State")
ylabel!("Average Price (Rupees)")

A grouped bar chart displaying the prices of some products in India grouped by state, with stacked bars.

Let's practice!

Introduction to Data Visualization with Julia