Class: Kiba::Extend::Transforms::Count::FieldValues

Inherits:
Object
  • Object
show all
Defined in:
lib/kiba/extend/transforms/count/field_values.rb

Overview

Adds the given field(s) to the row with nil value if they do not already exist in row

Examples

Input table is not shown separately. It is just name column of the results tables shown below. The blank value in name indicates an empty Ruby String object. The nil indicates a Ruby NilValue object.

Example 1

No placeholder value is given, so “NULL” is treated as a string value. count_empty defaults to false, so empty values are not counted.

Used in pipeline as:

 transform Count::FieldValues, field: :name, target: :ct, delim: ';'

Results in:

| name                 | ct |
|----------------------+----|
| Weddy                | 1  |
| NULL                 | 1  |
|                      | 0  |
| nil                  | 0  |
| Earlybird;Divebomber | 2  |
| ;Niblet              | 1  |
| Hunter;              | 1  |
| NULL;Earhart         | 2  |
| ;                    | 0  |
| NULL;NULL            | 2  |

Example 2

No placeholder value is given, so “NULL” is treated as a string value. count_empty is true, so empty values are counted. Note that fully empty field values are not counted, but when a delimiter is present, any empty values delimited by it are counted.

These options are functionally equivalent to those shown in example 4.

Used in pipeline as:

 transform Count::FieldValues, field: :name, target: :ct, delim: ';', count_empty: true

Results in:

| name                 | ct |
|----------------------+----|
| Weddy                | 1  |
| NULL                 | 1  |
|                      | 0  |
| nil                  | 0  |
| Earlybird;Divebomber | 2  |
| ;Niblet              | 2  |
| Hunter;              | 2  |
| NULL;Earhart         | 2  |
| ;                    | 2  |
| NULL;NULL            | 2  |

Example 3

Placeholder value is given, so “NULL” is treated as an empty value. count_empty default to false, so empty values, including any values that equal the given placeholder value, are not counted.

Used in pipeline as:

 transform Count::FieldValues, field: :name, target: :ct, delim: ';', placeholder: 'NULL'

Results in:

| name                 | ct |
|----------------------+----|
| Weddy                | 1  |
| NULL                 | 0  |
|                      | 0  |
| nil                  | 0  |
| Earlybird;Divebomber | 2  |
| ;Niblet              | 1  |
| Hunter;              | 1  |
| NULL;Earhart         | 1  |
| ;                    | 0  |
| NULL;NULL            | 0  |

Example 4

Placeholder value is given, so “NULL” is treated as an empty value. count_empty is true, so empty values are counted. Note that fully empty field values are not counted, but when a delimiter is present, any empty values delimited by it are counted.

These options are functionally equivalent to those shown in example 2.

Used in pipeline as:

 transform Count::FieldValues, field: :name, target: :ct, delim: ';', placeholder: 'NULL', count_empty: true

Results in:

| name                 | ct |
|----------------------+----|
| Weddy                | 1  |
| NULL                 | 1  |
|                      | 0  |
| nil                  | 0  |
| Earlybird;Divebomber | 2  |
| ;Niblet              | 2  |
| Hunter;              | 2  |
| NULL;Earhart         | 2  |
| ;                    | 2  |
| NULL;NULL            | 2  |

Instance Method Summary collapse

Constructor Details

#initialize(field:, target:, delim: Kiba::Extend.delim, placeholder: nil, count_empty: false) ⇒ FieldValues

Returns a new instance of FieldValues.

Parameters:

  • field (Symbol) —

    the field whose values should be counted

  • target (Symbol) —

    new field in which to record counts

  • delim (String) (defaults to: Kiba::Extend.delim) —

    value used to split

  • placeholder (String, NilValue) (defaults to: nil) —

    string that acts as a placeholder for empty value. If nil, nothing is used as a placeholder

  • count_empty (Boolean) (defaults to: false) —

    whether empty placeholder values should be counted



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# File 'lib/kiba/extend/transforms/count/field_values.rb', line 136

def initialize(field:, target:, delim: Kiba::Extend.delim,
  placeholder: nil, count_empty: false)
  @field = field
  @target = target
  @delim = delim
  @placeholder = placeholder
  @count_empty = count_empty
end

Instance Method Details

#process(row) ⇒ Object

Parameters:

  • row (Hash{ Symbol => String, nil }) 


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# File 'lib/kiba/extend/transforms/count/field_values.rb', line 146

def process(row)
  row[@target] = "0"
  val = row.fetch(@field, nil)
  return row unless val

  split = val.split(@delim, -1)
  to_count = handle_empty(split)
  row[@target] = to_count.length.to_s
  row
end