mathematical_expression

Computes a mathematical expression between multiple columns.

Usage

Compute a mathematical expression between multiple columns as multiplication, addition, division;

This calculator can be used with the following method:

mathematical_expression

Examples:

• computing a boolean variable 'flag' with a float quantity in order to set my quantity variable to 0 based on the values of my flag

• Add a constant to a predicted variable

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Main Parameters

The bold options represent the default values when the parameters are optional.

• input_columns list of columns used as input of the calculators

• output_columns list of columns added by the calculators

• global (true, false) Should this calculator be performed before data splitting during training for cross-validation

• steps [optionnal] (training, prediction, postprocessing) List of steps in a pipeline where columns from this calculator are added to the data. Note that when the training option is listed, the calculator is actually added during preprocessing.

• store_in_model [optionnal] (true, false) Please indicate whether the "calculated" columns by the calculator should be stored in the model or not to avoid recalculating them during prediction. This is only relevant if the calculated columns are added to both training and prediction. Without this parameter, the values will not be stored in the model. The following parameters only make sense if this parameter is set to true.

• stored_columns [required if store_in_model is true] List indicating the columns to be stored among the output_columns.

• stored_keys [required if store_in_model is true] List indicating the columns to use for identifying the correct values to join on the data for prediction among the stored values (logically, they are to be chosen from the input_columns).

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Specific Parameters

• expression (+, -, *, /, //, %, >, >=, <, <=, ==, !=) You can compose your expression with operators (+, -, *, /, //, %, >, >=, <, <=, ==, !=), column names, constants, parenthesis, white spaces.

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Examples

1. calculated_cols:
     add_a_b_minus_c_divided_by_3:
       method: mathematical_expression
       input_columns:
       - a
       - b
       - c
       output_columns:
       - add_a_b_minus_c_divided_by_3
       params:
         expression: (a + b - c) / 3

2. Imagine we want to tag the begin and the end of the month (salary day). Here we tag from the day 1 to 7 of the month and from 24 to 30/31. The input column day is provided by calulator date_attributes

   calculated_cols:  
     tag_begin_end_of_month_feat:
       method: mathematical_expression
       input_columns:
       - day
       output_columns:
       - tag_salary_days
       params:
         expression: (day < 8) + (day > 23)