tech.tablesaw.io

Class ColumnTypeDetector

java.lang.Object

tech.tablesaw.io.ColumnTypeDetector

public class ColumnTypeDetector
extends Object

Constructor Summary

Constructors

Constructor and Description
ColumnTypeDetector(List<ColumnType> typeArray)

Method Summary

Modifier and Type	Method and Description
ColumnType[]	detectColumnTypes(Iterator<String[]> rows, ReadOptions options) Estimates and returns the type for each column in the input text

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ColumnTypeDetector

public ColumnTypeDetector(List<ColumnType> typeArray)

Parameters:

typeArray - Types to choose from. When more than one would work, we pick the first of the options. The order these appear in is critical. The broadest must go last, so String must be at the end of the list. Any String read from the input will match string. If it were first on the list, you would get nothing but strings in your table. As another example, an integer type, should go before double. Otherwise double would match integers so the integer test would never be evaluated and all the ints would be read as doubles.

Method Detail

detectColumnTypes

public ColumnType[] detectColumnTypes(Iterator<String[]> rows,
                                      ReadOptions options)

Estimates and returns the type for each column in the input text

The type is determined by checking a sample of the data. Because only a sample of the data is checked, the types may be incorrect. If that is the case a Parse Exception will be thrown.

The method printColumnTypes() can be used to print a list of the detected columns that can be corrected and used to explicitly specify the correct column types.