Excel Reader (XLS)

This node reads a spread sheet and provides it at its output port.
It reads only data from one sheet, but it is possible to read multiple files that contain the same sheet name at once.
It can read only numeric, date, boolean and string data but, of course, no diagrams, pictures, or other items.
Currently supported KNIME types are String, TimeAndDate, Double, Boolean, and Int.
It reads in the data from the sheet and sets a type for all columns that is compatible with the data in that column (in the worst case "String" covers all).
The performance of the reader node is limited (due to the underlying library of the Apache POI project). Reading large files takes a very long time and uses a lot of memory (especially files in xlsx format when formula reevaluation is selected).

Options

File or Files in folder

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

Read from...

Select a file system which stores the data you want to read. There are three 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 choose a mountpoint. When selected, a new drop-down menu appears to choose the mountpoint.
• Custom URL: Allows to specify a URL (e.g. file://, http:// or knime:// protocol). 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 connection node to the newly added input port. The file system connection will then be shown in the drop down menu.

File, Folder or URL

Enter a URL when reading from Custom 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 destination from the "Browse..." dialog (browsing is not available for the Custom URL file system).

Include subfolders

When reading files from a folder, check this to include all matching files from subfolders of the defined folder.

Filter options

Press this button for file filtering options.

File filtering: File extension(s)

Enter file extensions used to filter files. Additionally, there is an option to choose whether the filter should work in a case sensitive or insensitive manner.
Note: A file extension has to be entered without the preceding dot. Multiple extensions have to be separated by a semicolon character (e.g. txt;log).

File filtering: File names

Select the desired filter method (regular expression or wildcard) and enter a valid expression to match the filenames of the files to be read. Additionally, there is an option to choose whether the filter should work in a case sensitive or insensitive manner.

File filtering options: Filter hidden files

Select if hidden files should be excluded.

Sheet to Read

After selecting a file, you can select the sheet from the available sheets in the file. If a folder is selected, the sheets of the first file in the folder are displayed.

Connect timeout[s]

Timeout in seconds when reading remote files. 0 means no timeout. In case it takes longer to connect to the host, the node fails to execute.
Note: This option is only active in case that the Custom URL file system is selected. Other file system don't use a timeout or the timeout is set directly in the specific connector node.

Column Names

If you want to use column names from the spread sheet, check "Table contains column names" and enter the number of the row that contains the column names (enter the number (starting at one), not the index).
Attention: In case multiple files are read, only the column names of the first file will be used. Rows with the specified index in all other files are not read and will be ignored.
If this option is not checked, default names are generated ("Col0", "Col1", etc.).

Row IDs

The option "Generate RowIDs (index incrementing, starting with 'Row0')" generates row ids starting from Row0 and produces all integer numbers till the end. The option "Generate RowIDs (index as per sheet content, skipped rows will increment index)" generates row ids based on sheet row indices starting from Row0, but numbers might get skipped when the row is skipped.
If you want to use row IDs from the spread sheet, check "Table contains row IDs" and provide the column that contains the row ids. Enter the label of the column ("A", "B", etc.) or the number (starting at one) of the column.
The rowIDs in the sheet must be unique, otherwise the execution fails. If you check "Make row IDs unique", the node will append a suffix to duplicates, ensuring row ID uniqueness. For very large data sets this could cause memory problems.

Select the columns and rows to read

Specify the region of the data sheet that should be read in. If you check "Read entire data sheet" the region provided by the data sheet file will be read in. This includes areas where diagrams, borders, coloring, etc. are placed and could create quite some empty rows or columns (see skip empty rows and columns options below).
If you want to read in a fixed area, remove the check mark and enter the first and last column, and first and last row to read. (Last row and column is optional, causing it to read to the last row or column provided by the sheet). For columns you need to enter the label ("A", "B", etc.), for rows enter the number (one-based).

Skip Empty Rows or Columns

If empty rows or columns should be removed from the result Data Table, check the appropriate option.

Skip hidden columns

Hidden columns are removed when checked.

Evaluation Error Handling

Specify the data that is inserted in a cell with an error. Not all formulas supported by all spreadsheet applications are supported by the XLS Reader Node. If an error occurs during formula evaluation (or if the spreadsheet contains an error cell), the selected data is inserted. You can either choose to insert a cell representing a missing value, or to insert a certain string pattern. A pattern causes the entire column to become a string column in case an error occurs. A missing value is type innocent, but also unobtrusive.

Reevaluate formulas

When checked it reads the whole file into memory and reevaluates the formulas before returning the result. This can cause errors when there are functions -not implemented by the Apache POI library- used on the sheet. When unchecked, xls files are still read to the memory, but the cached values are returned. For xlsx files, only the requested sheet is loaded when no reevaluation is requested and requires much less memory to return the cached values. If uncertain leave unchecked unless there is a concrete reason.

Disable Preview

Preview loading is disabled and no data table configuration is computed, so changes in the format of the xls(x) file will not generate errors after execution. The drawback of the enabled state of this option is that subsequent nodes do not have information about the output table structure.

Preview

The "Preview" tab shows you the output table with the current settings in the dialog. If the settings are invalid an error message will be displayed in this tab. The table updates only when the "refresh" button is clicked. A warning is shown, if the table content is out of sync with the current settings.

File Content

The "File Content" table shows you the content of the currently selected sheet. It shows the entire content (no settings are applied there). The column names here are the ones that need to be specified in the corresponding setting fields, row numbers are 0-based.

Views

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Workflows

• 008_Loops - 1KNIME Hub
• 009_Loops - 2KNIME Hub
• 01_Accessing_Transforming_and_Modeling_Time_SeriesKNIME Hub
• 01_Accessing_Transforming_and_Modeling_Time_SeriesKNIME Forum
• 01_Accessing_Transforming_and_Modeling_Time_SeriesKNIME Hub
• Show all 500 workflows

Links

• KNIME E-Learning Course: Excel Reader Node

  www.knime.com/knime-introductory-course/chapter2/section1/excel-reader-node
• Workflow - Join and append columns from different files in loop - Helpby armingrudd on 2020-02-27

  forum.knime.com/p/82819
• Excel Reader skips empty columnby mlauber71 on 2020-01-21

  forum.knime.com/p/79395

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