cdcmeasles

An R package to access and visualize CDC measles case data.

Overview

The cdcmeasles package provides tools to:

• Download measles case data directly from official CDC JSON endpoints
• Access both weekly (recent) and yearly (historical) case counts
• Create time series plots, bar charts, and choropleth maps
• Check data availability and retrieve metadata

Installation

Install the development version from GitHub:

# install.packages("devtools")
devtools::install_github("dwchal/cdcmeasles")

Quick Start

library(cdcmeasles)

# Check if data is available
is_data_available(verbose = TRUE)

# Download weekly data (recent cases)
weekly <- get_measles_data("weekly")
head(weekly)

# Download yearly data (historical)
yearly <- get_measles_data("yearly")
head(yearly)

# Get a quick summary of current year
get_current_year_summary()

Visualizations

The package includes several ggplot2-based visualization functions:

# Time series plot
weekly <- get_measles_data("weekly")
plot_measles_time_series(weekly, show_points = TRUE)

# Yearly bar chart
yearly <- get_measles_data("yearly")
plot_measles_bars(yearly, highlight_recent = TRUE)

# Historical time series
plot_measles_time_series(
  yearly,
  date_col = "year",
  title = "Historical Measles Cases"
)

For state-level data, create choropleth maps (requires maps package):

state_data <- data.frame(
  state = c("california", "texas", "new york"),
  cases = c(50, 30, 45)
)
plot_measles_state_map(state_data)

Data Sources

The package accesses two official CDC data endpoints:

Type	URL	Description
Weekly	https://www.cdc.gov/wcms/vizdata/measles/MeaslesCasesWeekly.json	Recent weekly case counts
Yearly	https://www.cdc.gov/wcms/vizdata/measles/MeaslesCasesYear.json	Historical annual data

Data Format

Weekly Data

Column	Type	Description
week_start	Date	Start of reporting week
week_end	Date	End of reporting week
cases	Integer	Number of reported cases

Yearly Data

Column	Type	Description
year	Integer	Year of data
cases	Integer	Total cases for year
states_with_cases	Integer	States reporting cases
outbreaks	Character	Outbreak descriptions

Functions

Data Retrieval

• get_measles_data() - Download weekly or yearly data
• is_data_available() - Check CDC endpoint accessibility
• get_measles_metadata() - Get dataset metadata
• get_cdc_urls() - View data endpoint URLs
• get_current_year_summary() - Quick summary of recent data

Data Processing

• clean_measles_data() - Standardize and clean data

Visualization

• plot_measles_time_series() - Time series line plot
• plot_measles_bars() - Bar chart for yearly data
• plot_measles_state_map() - US choropleth map
• plot_measles_dashboard() - Combined dashboard view

Dependencies

Required:

• httr
• jsonlite
• ggplot2
• rlang

Optional:

• maps (for plot_measles_state_map())
• patchwork (for plot_measles_dashboard())

License

MIT

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Disclaimer

This package is not officially affiliated with or endorsed by the CDC. The data is provided by the CDC and made available through this package for ease of access and analysis.

Note on Data Access

The CDC occasionally updates their data structure and URLs. If you encounter issues:

1. Check is_data_available(verbose = TRUE) for connectivity
2. Verify URLs with get_cdc_urls()
3. Visit the CDC measles page for updates
4. Report issues at https://github.com/dwchal/cdcmeasles/issues