pygrowup-erknet 0.9.4

Calculate z-scores of anthropometric measurements based on WHO and CDC child growth standards

pygrowup-erknet

modified version of: http://github.com/ewheeler/pygrowup

pygrowup calculates z-scores for the following anthropometric indicators:

• weight-for-age

• length/height-for-age

• weight-for-length/height

• head-circumference-for-age

• body-mass-index-for-age

based on the WHO Child Growth Standards:

• http://www.who.int/childgrowth/standards/en/
• http://www.who.int/entity/childgrowth/standards/technical_report/en/index.html

and can optionally use CDC growth standards:

• http://www.cdc.gov/growthcharts

REQUIREMENTS

• Python 3.8 or later

INSTALLATION

pip install pygrowup-erknet

EXAMPLE USAGE

Typical usage might look like this::

from pygrowup_erknet import Calculator
# Height adjustments are part of the WHO specification (see section 5.1)
# to correct for recumbent vs standing measurements,
# but none of the existing software seems to implement this.
# default is false so values are closer to those produced
# by igrowup software
#
# WHO specs include adjustments (see Chapter 7) to z-scores of weight-based
# indicators that are greater than +/- 3 SDs. These adjustments
# correct for right skewness and avoid making assumptions about
# the distribution of data beyond the limits of the observed values.
#
# However, when calculating z-scores in a live data collection
# situation, z-scores greater than +/- 3 SDs are likely to indicate
# data entry or anthropometric measurement errors and should not
# be adjusted. Instead, these large z-scores should be used to
# identify poor data quality and/or entry errors.
# These z-score adjustments are appropriate only when there
# is confidence in data quality.
#
# In this example, Calculator is initialized with its default values
# (i.e., ``calculator = Calculator()`` would do the same thing).
# The ``include_cdc`` option will enable CDC measurements for children >5 years.
# The ``override_tables`` option allows to provide a custom list of ``GrowthTable``. Can be used with ``CDC_TABLES`` to override the Who tables altogether.
calculator = Calculator(adjust_height_data=False,
                       include_cdc=False,
                       override_tables=None)

# The age in the calculator is always in months. To covert days to months, divide the age by 30.4375.

calculator.zscore_for_measurement(indicator='wfa' # allowed values are: bmifa, hcfa, lfa, hfa, wfa, wfh, wfl
                                    measurement=10.4, # weight in kg, height/lengt/head circumference in cm, bmi in kg/m2
                                    sex='M, # 'M' or 'F'
                                    index_value=22.45, #age in months or length/height in cm (depends on the indicator)
                                    is_recumbent_height=False) # ignored if adjust_height_data is set to False.

# The above method can be simplified using the following methods:

calculator.lhfa(measurement=10.4, age_in_months=22.45, sex='M', is_recumbent_height=False)

calculator.wfl(measurement=10.4, sex='M', length=84.8, is_recumbent_height=False)

calculator.wfh(measurement=10.4, sex='M', height=84.8, is_recumbent_height=False)

calculator.wfa(measurement=10.4, age_in_months=22.45, sex='M')

calculator.bmifa(measurement=14.46, age_in_months=22.45, sex='M')

calculator.hcfa(measurement=48.5, age_in_months=22.45, sex='M')

EXCEPTIONS

caller should watch for:

as well as more specific errors (all subclasses of RuntimeError and PyGrowUpError):

• DataNotFound raised when no data is not found for the requested observation.

• InvalidMeasurement raised when measurement (height/length, bmi, weight, head circumference) is invalid for a requested indicator.

• InvalidTableNameError raised when an invalid indicator (table) was requested (allowed values are: bmifa, hcfa, lfa, hfa, wfa, wfh, wfl).

• InvalidIndexErrorraised when an invalid index value was given for a requested indicator (usually age or length/height).

• InvalidAge (subclass of InvalidIndexError) raised when the age is invalid for a requested indicator.

• InvalidLengthError (subclass of InvalidIndexError) raised when the length/height is invalid for a requested indicator.

• InvalidSexError raised when the sex could not be inferred, allowed values are 'M' or 'F'.

TESTING

to run the tests: $ python -m pygrowup_erknet.tests

BUILDING

$ python setup.py sdist bdist_wheel

$ twine upload dist/*