SuperTextFiles

Import raw text, PDF and image files with if necessary an usage of Tesseract, an OCR application.

Authors

Loïc Aubrays, Fábio Torres Cabral (Aris Xanthos, original Text Files)

Signals

Inputs: Message

JSON Message controlling the list of imported text files

Outputs: Text data

Segmentation covering the content of imported text files

Installation of Tesseract

To use the OCR feature, an extra installation is needed. There are two parts to install, the engine itself, and the training data for a language. Please read the official documentation of Tesseract.

Description

This widget is designed to import the contents of one or several files in Orange Canvas. It outputs a segmentation containing a (potentially annotated) segment for each imported file.

This widget processes files with 3 methods.

For raw text files

The imported textual content is normalized in several ways:

• it is systematically converted to Unicode (from the encoding defined by the user)
• it is subjected to the canonical Unicode decomposition-recomposition technique (Unicode sequences such as LATIN SMALL LETTER C (U+0063) + COMBINING CEDILLA (U+0327) are systematically replaced by the combined equivalent, e.g. LATIN SMALL LETTER C WITH CEDILLA (U+00C7))
• it is stripped from the utf8 byte-order mark (if any)
• various forms of line endings (in particular \r\n and \r) are converted to a single form (namely \n)

For textual PDF files

The textual content is extracted from the PDF file in the order in the file, not in the reading view.

For pictures and PDF files

The textual content is extracted from the images with the Tesseract OCR

The interface of Super Text files is available in two versions, according to whether or not the Advanced Settings checkbox is selected.

Basic interface

In its basic version (see figure 1 below), the Text Files widget is limited to the import of a single text or textual PDF file. The interface contains a Source section enabling the user to select the input file. The Browse button opens a file selection dialog; the selected file then appears in the File path text field (it can also be directly inputted with the keyboard). The Encoding drop-down menu enables the user to specify the encoding of the file.

Figure 1: Super Text files widget (basic interface).

Note that the language is assumed to be English for OCR purposes (it can be specified otherwise using the advanced interface.

The Send button triggers the emission of a segmentation to the output connection(s). When it is selected, the Send automatically checkbox disables the button and the widget attempts to automatically emit a segmentation at every modification of its interface.

The text below the Send button indicates the number of characters in the single segment contained in the output segmentation, or the reasons why no segmentation is emitted (no input data, encoding issue, etc.).

Advanced interface

The advanced version of Super Text Files allows the user to import several files in a determined order; each file can moreover be associated to a distinct encoding and specific annotations. The emitted segmentation contains a segment for each imported file.

Figure 2: Super Text files widget (advanced interface).

The advanced interface (see figure 2 above) presents similarities with that of the URLs, Recode, and Segment widgets. The Sources section allows the user to select the input file(s) as well as their encoding, to determine the order in which they appear in the output segmentation, and optionally to assign an annotation. The list of imported files appears at the top of the window; the columns of this list indicate (a) the name of each file, (b) the corresponding annotation (if any), and (c) the encoding with which each is associated.

The first buttons on the right of the imported files’ list enable the user to modify the order in which they appear in the output segmentation (Move Up and Move Down), to delete a file from the list (Remove) or to completely empty it (Clear All). Except for Clear All, all these buttons require the user to previously select an entry from the list. Import List enables the user to import a file list in JSON format (see sections JSON im-/export format and File list in Textable documentation) and to add it to the previously selected sources. In the opposite Export List enables the user to export the source list in a JSON file.

The remainder of the Sources section allows the user to add new files to the list. The easiest way to do so is to first click on the Browse button, which opens a file selection dialog. After having selected one or more files in this dialog and validated the choice by clicking on Open, the files appear in the File paths field and can be added to the list by clicking on the Add button. It is also possible to type the complete paths of the files directly in the text field, separating the paths corresponding to the successive files with the string ” ” (space + slash + space).

Before adding one or more files to the list by clicking on Add, it is possible to select their encoding (Encoding), and to assign an annotation by specifying its key in the Annotation key field and the corresponding value in the Annotation value field. These three parameters (encoding, key, value) will be applied to each file appearing in the File paths field at the moment of their addition to the list with Add.

The PDF Password field allows password-protected files to be passed to the widget. Insert the password in the field and proceed as usual.

The OCR Language(s) field is needed by the OCR processes. By default, it contains English abbreviated by eng. Multilingual files are supported by complete the field with the languages separated by +. For example, eng+fra+ita. See all installable Tesseract data files. If nothing is indicated in this field, the language is assumed to be eng.

Force OCR enables the OCR processes of the widget while also extracting textual content. Enable this if textual and image content are both present in the file (or if extraction of textual content gives really bad results).

The Options section allows the user to specify the label affected to the output segmentation. The Import filenames with key checkbox enables the program to create for each imported file an annotation whose value is the file name (as displayed in the list) and whose key is specified by the user in the text field on the right of the checkbox. Similarly the button Auto-number with key enables the program to automatically number the imported files and to associate the number to the annotation key specified in the text field on the right.

The Send button triggers the emission of a segmentation to the output connection(s). When it is selected, the Send automatically checkbox disables the button and the widget attempts to automatically emit a segmentation at every modification of its interface.

The text below the Send button indicates the length of the output segmentation in characters, or the reasons why no segmentation is emitted (no selected file, encoding issue, etc.). In the example, the two segments corresponding to the imported files thus total up to 1’262’145 characters.

Remote control

Super Text Files is one the widgets that can be controlled by means of the Message widget. Indeed, it can receive in input a message consisting of a file list in JSON format (see sections JSON im-/export format and File list in Textable documentation), in which case the list of files specified in this message replaces previously imported sources (if any). Note that removing the incoming connection from the Message instance will not, by itself, remove the list of files imported in this way from the Super Text Files instance’s interface; conversely, this list of files can be modified using buttons Move up/down, Remove, etc. even if the incoming connection from the Message instance has not been removed. Finally, note that if a Super Text Files instance has the basic version of its interface activated when an incoming connection is created from an instance of Message, it automatically switches to the advanced interface.

Messages

Information

Data correctly sent to output: <n> segments (<m> characters).

This confirms that the widget has operated properly.

Settings were (or Input has) changed, please click ‘Send’ when ready.

Settings and/or input have changed but the Send automatically checkbox has not been selected, so the user is prompted to click the Send button (or equivalently check the box) in order for computation and data emission to proceed.

No data sent to output yet: no file selected.

The widget instance is not able to emit data to output because no input file has been selected.

No data sent to output yet, see ‘Widget state’ below.

A problem with the instance’s parameters and/or input data prevents it from operating properly, and additional diagnostic information can be found in the Widget state box at the bottom of the instance’s interface (see Warnings and Errors below).

Warnings

No label was provided.

A label must be entered in the Output segmentation label field in order for computation and data emission to proceed.

No annotation key was provided for auto-numbering.

The Auto-number with key checkbox has been selected and an annotation key must be specified in the text field on the right in order for computation and data emission to proceed.

JSON message on input connection doesn’t have the right keys and/or values.

The widget instance has received a JSON message on its Message input channel and the keys and/or values specified in this message do not match those that are expected for this particular widget type (see sections JSON im-/export format and File list in Textable documentation).

JSON parsing error.

The widget instance has received data on its Message input channel and the data couldn’t be correctly parsed. Please use a JSON validator to check the data’s well-formedness.

Errors

Couldn’t open file or Couldn’t open file ‘<filepath>’.

A file couldn’t be opened and read, typically because the specified path is wrong.

Encoding error or Encoding error: file ‘<filepath>’.

A file couldn’t be read with the specified encoding (it must be in another encoding).

Please make sure all Tesseract parameter files for language(s) ‘<languages>’ have been installed..

One or more Tesseract language packages are probably missing.

Tesseract is not installed or it’s not in your path.

Add the directory where the tesseract-OCR binaries are located to the Environment Path variables, probably C:\Program Files\Tesseract-OCR