Line Reader

Options

Settings

Read from

Select a file system which stores the data you want to read. There are four default file system options to choose from:

• Local File System: Allows you to select a file/folder from your local system.
• Mountpoint: Allows you to read from a mountpoint. When selected, a new drop-down menu appears to choose the mountpoint. Unconnected mountpoints are greyed out but can still be selected (note that browsing is disabled in this case). Go to the KNIME Explorer and connect to the mountpoint to enable browsing. A mountpoint is displayed in red if it was previously selected but is no longer available. You won't be able to save the dialog as long as you don't select a valid i.e. known mountpoint.
• Relative to: Allows you to choose whether to resolve the path relative to the current mountpoint, current workflow or the current workflow's data area. When selected a new drop-down menu appears to choose which of the three options to use.
• Custom/KNIME URL: Allows to specify a URL (e.g. file://, http:// or knime:// protocol). When selected, a spinner appears that allows you to specify the desired connection and read timeout in milliseconds. In case it takes longer to connect to the host / read the file, the node fails to execute. Browsing is disabled for this option.

To read from other file systems, click on ... in the bottom left corner of the node icon followed by Add File System Connection port. Afterwards, connect the desired file system connector node to the newly added input port. The file system connection will then be shown in the drop-down menu. It is greyed out if the file system is not connected in which case you have to (re)execute the connector node first. Note: The default file systems listed above can't be selected if a file system is provided via the input port.

Mode

Select whether you want to read a single file or multiple files in a folder. When reading files in a folder, you can set filters to specify which files and subfolders to include (see below).

Filter options

Only displayed if the mode Files in folder is selected. Allows to specify which files should be included according to their file extension and/or name. It is also possible to include hidden files. The folder filter options enable you to specify which folders should be included based on their name and hidden status. Note that the folders themselves will not be included, only the files they contain.

Include subfolders

If this option is checked, the node will include all files from subfolders that satisfy the specified filter options. If left unchecked, only the files in the selected folder will be included and all files from subfolders are ignored.

File, Folder or URL

Enter a URL when reading from Custom/KNIME URL, otherwise enter a path to a file or folder. The required syntax of a path depends on the chosen file system, such as "C:\path\to\file" (Local File System on Windows) or "/path/to/file" (Local File System on Linux/MacOS and Mountpoint). For file systems connected via input port, the node description of the respective connector node describes the required path format. You can also choose a previously selected file/folder from the drop-down list, or select a location from the "Browse..." dialog. Note that browsing is disabled in some cases:

• Custom/KNIME URL: Browsing is always disabled.
• Mountpoint: Browsing is disabled if the selected mountpoint isn't connected. Go to the KNIME Explorer and connect to the mountpoint to enable browsing.
• File systems provided via input port: Browsing is disabled if the connector node hasn't been executed since the workflow has been opened. (Re)execute the connector node to enable browsing.

The location can be exposed as or automatically set via a path flow variable.

Fail on differing specs

This option is only available if the 'Files in folder' option is selected. If the option is select and the specs of the files are different the node will fail.

Row header prefix

This option allows you to specify the prefix of the row header. The default is "Row" and the resulting row headers are "Row0", "Row1" and so on.

Column Header

If the option 'Use fix column header' is checked the name you the output column can be set manually in the text field, which is only active if the option is checked. The default name is 'Column'. If the option 'Use first line as column header' is checked the name of the output column equals the first row of the read file.

Advanced Settings

Skip empty lines

If this option is checked empty lines will be skipped and are not added to the output.

Replace empty lines with missing cells

If this option is checked empty lines will be replaced by a missing cell.

Replace empty lines

If this option is checked empty lines will be replaced by the text entered in the text field.

Match input against regex

If this option is checked every line will be checked against the regular expression in the text field. For example '12.*' will only match lines starting with 12 and have zero or more characters afterwards. The default value is '.*' which matches everything.

Limit data rows

With this option you can limit the number of rows which will be read and be output by the node.

Path column

If checked, the node will append a path column with the provided name to the output table. This column contains for each row which file it was read from. The node will fail if adding the column with the provided name causes a name collision with any of the columns in the read table.

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"

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Workflows

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Links

• File Reader node does not read/show databy qqilihq on 2024-02-05

  forum.knime.com/p/248836

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