tech.tablesaw.io.csv

Class CsvReader

java.lang.Object

tech.tablesaw.io.csv.CsvReader

@Immutable
public class CsvReader
extends Object

Method Summary

Modifier and Type	Method and Description
protected static ColumnType[]	detectColumnTypes(InputStream stream, boolean header, char delimiter, boolean skipSampling) Estimates and returns the type for each column in the delimited text file file
static Table	headerOnly(ColumnType[] types, boolean header, char columnSeparator, File file) Returns a Table constructed from a CSV File with the given file name
static String	printColumnTypes(String csvFileName, boolean header, char delimiter) Returns a string representation of the column types in file csvFilename, as determined by the type-detection algorithm
static Table	read(ColumnType[] types, boolean header, char columnSeparator, String fileName) Deprecated. use read(CsvReadOptions) instead
static Table	read(ColumnType[] types, String... fileNames) Deprecated. use read(CsvReadOptions) instead
static Table	read(CsvReadOptions options)
static Table	read(File file, boolean header, char delimiter) Deprecated. use read(CsvReadOptions) instead
static Table	read(File file, String tableName, boolean header, char delimiter, boolean skipSampling)
static Table	read(File file, String tableName, ColumnType[] types, boolean header, char columnSeparator) Deprecated. use read(CsvReadOptions) instead
static Table	read(InputStream stream, String tableName, boolean header, char delimiter) Deprecated. use read(CsvReadOptions) instead
static Table	read(InputStream stream, String tableName, boolean header, char delimiter, boolean skipSampling) Deprecated. use read(CsvReadOptions) instead
static Table	read(InputStream stream, String tableName, ColumnType[] types, boolean header, char columnSeparator) Deprecated. use read(CsvReadOptions) instead

Methods inherited from class java.lang.Object

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

Method Detail

read

@Deprecated
public static Table read(ColumnType[] types,
                                     String... fileNames)
                              throws IOException

Deprecated. use read(CsvReadOptions) instead

Constructs and returns a table from one or more CSV files, all containing the same column types

This constructor assumes the files have a one-line header, which is used to populate the column names, and that they use a comma to separate between columns.

Throws:

IOException - If there is an issue reading any of the files

read

@Deprecated
public static Table read(ColumnType[] types,
                                     boolean header,
                                     char columnSeparator,
                                     String fileName)
                              throws IOException

Deprecated. use read(CsvReadOptions) instead

Returns a Table constructed from a CSV File with the given file name

The @code{fileName} is used as the initial table name for the new table

Parameters:

types - An array of the types of columns in the file, in the order they appear

header - Is the first row in the file a header?

columnSeparator - the delimiter

fileName - The fully specified file name. It is used to provide a default name for the table

Returns:

A Table containing the data in the csv file.

Throws:

IOException - if file cannot be read

read

@Deprecated
public static Table read(File file,
                                     boolean header,
                                     char delimiter)
                              throws IOException

Deprecated. use read(CsvReadOptions) instead

Returns the given file after auto-detecting the column types, or trying to

Parameters:

file - The file to load

header - True if the file has a single header row. False if it has no header row. Multi-line headers are not supported

delimiter - a char that divides the columns in the source file, often a comma or tab

Returns:

A table containing the data from the file

Throws:

IOException - if file cannot be read

read

@Deprecated
public static Table read(InputStream stream,
                                     String tableName,
                                     boolean header,
                                     char delimiter)
                              throws IOException

Deprecated. use read(CsvReadOptions) instead

Returns the given file after auto-detecting the column types, or trying to

Parameters:

stream - The CSV

tableName - Name to give the table

header - True if the file has a single header row. False if it has no header row. Multi-line headers are not supported

delimiter - a char that divides the columns in the source file, often a comma or tab

Returns:

A table containing the data from the file

Throws:

IOException - if file cannot be read

read

public static Table read(File file,
                         String tableName,
                         boolean header,
                         char delimiter,
                         boolean skipSampling)
                  throws IOException

Throws:

IOException

read

@Deprecated
public static Table read(InputStream stream,
                                     String tableName,
                                     boolean header,
                                     char delimiter,
                                     boolean skipSampling)
                              throws IOException

Deprecated. use read(CsvReadOptions) instead

This method buffers the entire InputStream. Use the method taking a File for large input

Throws:

IOException

read

@Deprecated
public static Table read(File file,
                                     String tableName,
                                     ColumnType[] types,
                                     boolean header,
                                     char columnSeparator)
                              throws IOException

Deprecated. use read(CsvReadOptions) instead

Throws:

IOException

read

@Deprecated
public static Table read(InputStream stream,
                                     String tableName,
                                     ColumnType[] types,
                                     boolean header,
                                     char columnSeparator)
                              throws IOException

Deprecated. use read(CsvReadOptions) instead

Throws:

IOException

read

public static Table read(CsvReadOptions options)
                  throws IOException

Throws:

IOException

headerOnly

public static Table headerOnly(ColumnType[] types,
                               boolean header,
                               char columnSeparator,
                               File file)
                        throws IOException

Returns a Table constructed from a CSV File with the given file name

The @code{fileName} is used as the initial table name for the new table

Parameters:

types - An array of the types of columns in the file, in the order they appear

header - Is the first row in the file a header?

columnSeparator - the delimiter

file - The fully specified file name. It is used to provide a default name for the table

Returns:

A Relation containing the data in the csv file.

Throws:

IOException - if file cannot be read

printColumnTypes

public static String printColumnTypes(String csvFileName,
                                      boolean header,
                                      char delimiter)
                               throws IOException

Returns a string representation of the column types in file csvFilename, as determined by the type-detection algorithm

This method is intended to help analysts quickly fix any erroneous types, by printing out the types in a format such that they can be edited to correct any mistakes, and used in an array literal

For example:

LOCAL_DATE, // 0 date SHORT_INT, // 1 approval CATEGORY, // 2 who

Note that the types are array separated, and that the index position and the column name are printed such that they would be interpreted as comments if you paste the output into an array:

ColumnType[] types = { LOCAL_DATE, // 0 date SHORT_INT, // 1 approval CATEGORY, // 2 who }

Throws:

IOException - if file cannot be read

detectColumnTypes

protected static ColumnType[] detectColumnTypes(InputStream stream,
                                                boolean header,
                                                char delimiter,
                                                boolean skipSampling)
                                         throws IOException

Estimates and returns the type for each column in the delimited text file file

The type is determined by checking a sample of the data in the file. 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.

Throws:

IOException