Anthro

A Ruby gem for calculating anthropometric z-scores and percentiles based on the WHO Growth Charts and CDC Growth Charts.

Install the gem and add to the application's Gemfile by executing:

bundle add anthro

If bundler is not being used to manage dependencies, install the gem by executing:

gem install anthro

require 'anthro'

# Weight (month-based)
calc = Anthro.weight_for_age(sex: "male", age_months: 24.5, value: 13.0)
puts "Z-Score: #{calc.z_score.round(2)}"
puts "Percentile: #{calc.percentile.round(2)}%"

# Weight (days-based): days devided by 30.4375
calc = Anthro.weight_for_age(sex: "male", age_days: 3653, value: 33.0) # ~120 months
puts "Z-Score: #{calc.z_score.round(2)}"
puts "Percentile: #{calc.percentile.round(2)}%"

# Height
calc = Anthro.height_for_age(sex: "female", age_days: 1461, value: 100.0) # ~48 months
puts "Z-Score: #{calc.z_score.round(2)}"
puts "Percentile: #{calc.percentile.round(2)}%"

# BMI
calc = Anthro.bmi_for_age(sex: "male", age_months: 36, value: 16.0)
puts "Z-Score: #{calc.z_score.round(2)}"
puts "Percentile: #{calc.percentile.round(2)}%"

# Head Circumference
calc = Anthro.head_circumference_for_age(sex: "female", age_months: 12, value: 46.0)
puts "Z-Score: #{calc.z_score.round(2)}"
puts "Percentile: #{calc.percentile.round(2)}%"

• Anthro.weight_for_age(sex:, age_months: or age_days:, value:) (0–20 years)
• Anthro.height_for_age(sex:, age_months: or age_days:, value:) (0–20 years)
• Anthro.bmi_for_age(sex:, age_months: or age_days:, value:) (2–20 years)
• Anthro.head_circumference_for_age(sex:, age_months: or age_days:, value:) (0–2 years)

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

This gem includes WHO and CDC 2000 growth chart data from WHO Growth Charts Data files and CDC Growth Charts Data Files.

• Birth to 2 years (WHO)

  • Weight-for-age charts: Boys
  • Weight-for-age charts: Girls
  • Length-for-age charts: Boys
  • Length-for-age charts: Girls
  • Head circumference-for-age charts: Boys
  • Head circumference-for-age charts: Girls

• 2 to 20 years (CDC)

  • Weight-for-age charts
  • Stature-for-age charts
  • BMI-for-age charts

Bug reports and pull requests are welcome on GitHub at https://github.com/hms-dbmi/anthro.

See the LICENSE file for license rights and limitations (MIT).