init()
Creates an empty, invalid column used to remove an existing column from a data table.
Declaration
init()Return Value
An empty, invalid column.
Discussion
Use this initializer to create an empty column that, when assigned to the name of an existing column within a data table, will remove that column from the table.
For example, to remove a column from a data table, first start with a variable data table.
let data: [String: MLDataValueConvertible] = [
"Day": ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"],
"Temperature": [91.3, 85.8, 79.5, 83.4, 72.2]
]
var table = try MLDataTable(dictionary: data)
print(table)
/* Prints...
Columns:
Day string
Temperature float
Rows: 5
Data:
+----------------+----------------+
| Day | Temperature |
+----------------+----------------+
| Monday | 91.3 |
| Tuesday | 85.8 |
| Wednesday | 79.5 |
| Thursday | 83.4 |
| Friday | 72.2 |
+----------------+----------------+
[5 rows x 2 columns]
*/Then use init() to create an empty column.
let emptyColumn = MLUntypedColumn()Finally, use subscript(_:) to remove the existing column from the data table by setting the empty column to the name of that existing column.
// Remove the "Temperature" column from the data table
table["Temperature"] = emptyColumn
print(table)
/* Prints...
Columns:
Day string
Rows: 5
Data:
+----------------+
| Day |
+----------------+
| Monday |
| Tuesday |
| Wednesday |
| Thursday |
| Friday |
+----------------+
[5 rows x 1 columns]
*/