new procedure: run_op

[semio]

Reason

Some datapoints are made with other datapoints by running math operators. We need a procedure for this task.

API

run_op accepts following parameters:

• ingredients: the ingredients to run operation.
• op: a dictionary, which are new_key: calculation pairs. For example:

{
    # male_population_0_14_years and female_population_0_14_years should exist 
    # in the ingredient
    sex_ratio_0_14_years: "male_population_0_14_years / female_population_0_14_years"
}

[semio]

example:

• example for running simple calculation on one column: https://github.com/semio/ddf--gapminder--systema_globalis/blob/feature/autogenerated/etl/recipes/recipe_bp.yaml
• example for running calculation on multiple columns: https://github.com/semio/ddf--gapminder--systema_globalis/blob/feature/autogenerated/etl/recipes/recipe_fao.yaml