Functions¶

Functions operate at the row level.

if_else¶

if_else(condition, expr_if_true, expr_if_false)
// A ternary operator is also supported.
(condition ? expr_if_true : expr_if_false)

• condition - An expression that evaluates to TRUE or FALSE.
• expr_if_true - Value to return if condition=-TRUE
• expr_if_false - Value to return if condition==FALSE

The if_else function evaluates an expression and returns expr_if_true or expr_if_false depending on the evaluation of condition.

flavor: if_else(flavor == "Chocolate", sugar > 50, sugar < 50)

max¶

Returns the max of arguments passed

orders: max(1,2,3) == 3         # Returns 3 == 3; true
items: max(col1, col2, col3)    # Returns the max value for the given row of col1-3.
inventory: max(col1)            # This does not return the max for an entire column; col1 is a scaler value.

min¶

Returns the minimum of arguments passed

to_lower¶

Converts a string to lowercase.

to_upper¶

Converts a string to uppercase.

replace¶

replace(value, find, replace)

count¶

count(column)

Returns the number of times the passed value(s) have been observed.

color: count(color) <= 20 # Fails if a value is observed more than 20x times.
configuration: count(color, size) <= 10 # Fails if the combination of values is observed more than 10 times.

null coalescence¶

?? can be used to set a default value.

(colname ?? 1) == 1 # returns TRUE if colname==NA/nil

Two-Pass Functions¶

Two-pass functions allow for more advanced expressions to be evaluated, but they require a first-pass through the file to collect information.

group_count¶

group_count(group_column, count_column, eq_value)

group_count will group data by the group_column, and count the number of occurences of eq_value in the count_column.

example

family_id: is_int()
person: group_count(person, is_head_of_household, true) == 1
is_head_of_household: is_bool()

In the example above, we are checking to see that only one person in a family is set to true for the column is_head_of_household. If you have missing data in your grouping column you may need use an if_else statement to conditionally validate a row as true:

family_id: is_int()
person: if_else(is_missing(), true, group_count(person, is_head_of_household, true) == 1)
is_head_of_household: is_bool()