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Simple File Reader

StreamableKNIME Base Nodes version 4.3.2.v202103021015 by KNIME AG, Zurich, Switzerland

This node reads local and remote files. It can be configured to read the most common formats. If the file has a more complex structure, use the File Reader node which has more configuration options.

When you open the node's configuration dialog and provide a filename, it tries to guess the column specs by analyzing the content of the file. By default, only the first 50 rows are analyzed. You can change this setting in the 'Limit Rows' tab. The file analysis can also be cut short by clicking the "Stop file scanning" button, which shows up if the analysis takes longer. If the file is not analyzed completely, it could happen that the preview looks fine, but the execution of the node fails when it reads the lines it didn't analyze. Check the results of the analyzed file in the preview table and increase the number of rows scanned for guessing the spec if necessary.

Options

Settings

Input location
Enter a valid file name or URL. You can also choose a previously read file from the drop-down list, or select a file from the "Browse..." dialog.
Connection timeout [s]
Timeout in seconds for connections when reading remote files.
Column delimiter
The character string delimiting columns. Use '\t' for tab character. Can be detected automatically.
Row delimiter
The character string delimiting rows. Use '\n' for new line character. Can be detected automatically.
Quote char
The quote character. Can be detected automatically.
Quote escape char
The character is used for escaping quotes inside an already quoted value. Can be detected automatically.
Autodetect format
By pressing this button, the "Column delimiter", "Row delimiter", "Quote char" and "Quote escape char" get automatically detected, though it is not guaranteed that the correct values are being detected.
The auto detection by default is based on the first 1024 * 1024 bytes of the selected file, but can be adjusted by clicking the settings button next to this option. The format can only be detected if the read number of bytes comprises one full data row and the autodetection will take at most 20 data rows into account. It is assumed that data rows are separated by linebreaks. Note that the "Skip first lines" option as well as the specified "Comment char" will be used when guessing the files format.
Comment char
A character indicating line comments.
Has column header
Select this box if the first row contains column name headers.
Has row ID
Select this box if the first column contains row IDs (no duplicates allowed).
Support short data rows
Select this box if some rows may be shorter than others (filled with missing values).

Transformation

Transformations
This tab displays every column as a row in a table that allows modifying the structure of the output table. It supports reordering, filtering and renaming columns. It is also possible to change the type of the columns. Reordering is done via drag-and-drop. Just drag a column to the position it should have in the output table. Whether and where to add unknown columns during execution is specified via the special row <any unknown new column>. Note that the positions of columns are reset in the dialog if a new file or folder is selected.
Reset order
Resets the order of columns to the order in the input file/folder.
Reset filter
Clicking this button will reset the filters i.e. all columns will be included.
Reset names
Resets the names to the names that are read from file or created if the file/folder doesn't contain column names.
Reset types
Resets the output types to the default types guessed from the input file/folder.
Reset all
Resets all transformations.
Enforce types
Controls how columns whose type changes are dealt with. If selected, we attempt to map to the KNIME type you configured and fail if that's not possible. If unselected, the KNIME type corresponding to the new type is used.

Advanced Settings

Limit memory per column
If selected the memory per column is restricted to 1MB in order to prevent memory exhaustion. Uncheck this option to disable these memory restrictions.
Maximum number of columns
Sets the number of allowed columns (default 8192 columns) to prevent memory exhaustion. The node will fail if the number of columns exceeds the set limit.
Quote options
  • Remove quotes and trim whitespaces: Quotes will be removed from the value followed by trimming any leading/trailing whitespaces.
  • Keep quotes: The quotes of a value will be kept. Note: No trimming will be done inside the quotes.
Replace empty quoted strings with missing values
Select this box if you want quoted empty strings to be replaced by missing value cell.
Table specification
If enabled, only the specified number of input rows are used to analyze the file (i.e to determine the column types). This option is recommended for long files where the first n rows are representative for the whole file. The "Skip first data rows" option has no effect on the scanning. Note also, that this option and the "Limit data rows" option are independent from each other, i.e., if the value in "Limit data rows" is smaller than the value specified here, we will still read as many rows as specified here.
Support changing file schemas
If selected, the reader will compute the table specification on execution. This behavior is required if the content of the configured file/folder changes between executions, i.e., columns are added/removed to/from file(s) or their types change. NOTE: When checked, the node will not output a table specification during configure and won't apply transformations (therefore the transformation tab is disabled).
Number format
Allows to specify the thousands and decimal separator character for parsing numbers. The thousands separator is used for integer, long and double parsing, while the decimal separator is only used for the parsing of double values. Note that the two must differ. While it is possible to leave the thousands separator unspecified, you must always provide a decimal separator.

Limit Rows

Skip first lines
If enabled, the specified number of lines are skipped in the input file before the parsing starts. Use this option to skip lines that do not fit in the table structure (e.g. mult-line comments)
Skip first data rows
If enabled, the specified number of valid data rows are skipped. This has no effect on which row will be chosen as column header.
Limit data rows
If enabled, only the specified number of data rows are read. The column header row (if selected) is not taken into account.

Simple File Reader Encoding

Encoding
To read a file that contains characters in a different encoding, you can select the character set in this tab (UTF-8, UTF-16, etc.), or specify any other encoding supported by your Java VM. The default value uses the default encoding of the Java VM, which may depend on the locale or the Java property "file.encoding"

Output Ports

Icon
File being read with number and types of columns guessed automatically.

Best Friends (Incoming)

Best Friends (Outgoing)

Workflows

Installation

To use this node in KNIME, install KNIME Base nodes from the following update site:

KNIME 4.3

A zipped version of the software site can be downloaded here.

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Developers

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