Data Structure

The whole sense of soylent is to provide all the nutrients needed by the body, in an easy to mix way.

This module contains the different classes we need to represent an alimentation

In the most basic form, we have a recipe, containing quantities of ingredients. An ingredient in turn contains certain quantities of nutrients.

In order to avoid creating a new file format, and to get all the goodies that comes with it, for example migration scripts, we use SQLAlchemy to manage the storage.

In order to simplify the management and calculations for the physical quantities, we use magnitude

Nutrients types

class models.Nutrient(name)

A Nutriment is pretty much anything that the body needs to be fed in order to work properly.

As for the relevant parts, all nutrients have a name, but some have more than one (think translation). Some have a minimal amount, other are optional. Some have a maximal amount, other can be consumed without problems. Then there are multiple recommended values, according to different guidelines, like the US recommended Dietary Reference Intake, or the EU-Directive 2008-100-EC.

given that most of these are optional, there is no reason to put them in the class itself.

They will be added in due time as needed.

A nitrient by itself doesn’t do a lot, so we kept the methods down to a minimum.

class models.Macronutrient(name, conversion_factor)

A Macronutrient is the kind of nutrient that can be converted to energy by the body, as described in the Food energy article on wikipedia.

This class derives from Nutrient, using concrete inheritance mapping to build the relationship.

conversion_factor

energy_per_weight

per default, the energy per weight is a magnitude expressed in Joules per gram.

There are different sources of macro nutrients, represented as subclasses of Macronutrient. For the moment, only the Carbohydrate, Fat and Protein are represented.

class models.Carbohydrate(name)

This class is used to represent a type of Carbohydrate.

It has no specific attribute or method.

class models.Fat(name, saturated, monounsaturated, polyunsaturated)

This class is used to represent different types of Fat.

It has three attributes, all Booleans, to indicate kind of saturation of the fat:

saturated

monounsaturated

polyunsaturated

class models.Protein(name, essential)

This class is the result of a misunderstanding on my part. Instead of being used to represent Protein, it is used to represent the different Amino acids.

essential

an amino acid is essential if it cannot be synthesized by the body.

Ingredient

Now that we have the nutrients, we can pack them in ingredients.

This is done using two classes:

class models.Ingredient(name, serving_size, serving_unit)

An ingredient has a name, logically, it is also measured in a specific unit and contains some nutrients per servings.

serving

read/write property for the serving as a physical quantity.

The instances also contains different read only properties representing the different kind of macronutrients contained in the Ingredient as a list of IngredientNutrient.

macronutrients

carbohydrates

fats

proteins

energy_per_serving(self, serving)

returns the energy contained in a serving in Joules. This is calculated based on the macronutrients contained in the ingredient.

Interrestingly, it sometimes is lower than the energy per serving indicated on the package.

In the same way that there are four properties for the macronutrients, there are three different methods to return the energy provided by the different kinds of macronutrients for a given serving: .. method:: carbohydrates_per_serving(self, serving) .. method:: fats_per_serving(self, serving) .. method:: proteins_per_serving(self, serving)

class models.IngredientNutrient(ingredient, nutrient, serving_amount, serving_size)

This class is an association object to join the ingredients with their nutrients.

Both ingredient and nutrient can be references using the corresponding attributes ingredient and nutrient.

concentration

A property representing the concentration of the nutrient for a serving, e.g. ‘5 g/ml’.

weight_per_serving(serving)

The amount of nutrient of a given serving of the ingredient.