R Can't Read Arff File Relative Path

Read ARFF (Advanced File Connectors)

Synopsis

This operator is used for reading an ARFF file.

Description

This operator can read ARFF (Attribute-Relation File Format) files known from the machine learning library Weka. An ARFF file is an ASCII text file that describes a list of instances sharing a set of attributes. ARFF files were developed by the Automobile Learning Project at the Department of Reckoner Science of The University of Waikato for utilize with the Weka machine learning software. Delight written report the attached Example Process for understanding the basics and construction of the ARFF file format. Delight note that when an ARFF file is written, the roles of the attributes are non stored. Similarly when an ARFF file is read, the roles of all the attributes are set up to regular.

Input

• file

  An ARFF file is expected as a file object which can be created with other operators with file output ports like the Read File operator.

Output

• output (Data Table)

  This port delivers the ARFF file in tabular form along with the meta information. This output is like to the output of the Recollect operator.

Parameters

• data_fileThe path of the ARFF file is specified here. It tin can be selected using the choose a file button. Range: filename
• encodingThis is an expert parameter. A long listing of encoding is provided; users tin select whatever of them. Range: selection
• read_not_matching_values_as_missingsThis is an expert parameter. If this parameter is set to true, values that do not friction match with the expected value type are considered every bit missing values and are replaced by '?'. For instance if 'abc' is written in an integer cavalcade, it will exist treated as a missing value. Question mark (?) in ARFF file is besides read equally missing value. Range: boolean
• decimal_characterThis character is used as the decimal character. Range: char
• grouped_digitsThis parameter decides whether grouped digits should be parsed or non. If this parameter is fix to true, the group character parameter should be specified. Range: boolean
• grouping_characterThis parameter is bachelor only when the grouped digits parameter is set to true.This character is used as the grouping character. If it is found between numbers, the numbers are combined and this character is ignored. For example if "22-14" is nowadays in the ARFF file and "-" is set as grouping grapheme, and so "2214" will be stored. Range: char
• infinity_stringThis parameter tin can be set to parse a specific infinity representation (east.g. "Infinity"). If information technology is non set, the local specific infinity representation will be used. Range: string

Tutorial Processes

The nuts of the ARFF

The 'Iris' data set is loaded using the Retrieve operator. The Write ARFF operator is applied on it to write the 'Iris' data set into an ARFF file. The instance prepare file parameter is set to 'D:\Iris'. Thus an ARFF file is created in the 'D' drive of your computer with the name 'Iris'. Open this file to see the structure of an ARFF file.

ARFF files take two distinct sections. The kickoff section is the Header information, which is followed by the Data data. The Header of the ARFF file contains the name of the Relation and a list of the attributes. The proper noun of the Relation is specified after the @RELATION statement. The Relation is ignored by RapidMiner. Each attribute definition starts with the @Aspect statement followed past the attribute name and its blazon. The resultant ARFF file of this Example Process starts with the Header. The name of the relation is 'RapidMinerData'. After the proper noun of the Relation, six attributes are divers.

Attribute declarations take the form of an ordered sequence of @Attribute statements. Each attribute in the data prepare has its ain @ATTRIBUTE statement which uniquely defines the name of that attribute and its data blazon. The lodge of declaration of the attributes indicates the column position in the data section of the file. For example, in the resultant ARFF file of this Example Process the 'label' attribute is declared at the end of all other attribute declarations. Therefore values of the 'characterization' attribute are in the final column of the Information department.

The possible attribute types in ARFF are: numeric integer existent {nominalValue1,nominalValue2,...} for nominal attributes string for nominal attributes without distinct nominal values (it is however recommended to utilize the nominal definition in a higher place as often every bit possible) date [appointment-format] (currently not supported by RapidMiner)

You can see in the resultant ARFF file of this Example Process that the attributes 'a1', 'a2', 'a3' and 'a4' are of real type. The attributes 'id' and 'label' are of nominal type. The distinct nominal values are also specified with these nominal attributes.

The ARFF Data department of the file contains the information annunciation line @Data followed by the bodily example data lines. Each case is represented on a single line, with carriage returns denoting the terminate of the example. Attribute values for each example are delimited by commas. They must appear in the social club that they were declared in the Header section (i.e. the data corresponding to the n-th @Attribute declaration is always the north-th field of the example line). Missing values are represented by a single question marker (?).

A percent sign (%) introduces a annotate and volition be ignored during reading. Attribute names or example values containing spaces must be quoted with unmarried quotes ('). Please note that in RapidMiner the sparse ARFF format is currently only supported for numerical attributes. Please apply one of the other options for thin data files provided by RapidMiner if yous too demand sparse data files for nominal attributes.

Reading an ARFF file using the Read ARFF operator

The ARFF file that was written in the starting time Example Process using the Write ARFF operator is retrieved in this Example Process using the Read ARFF operator. The data file parameter is set to 'D:\Iris'. Please make sure that you specify the right path. All other parameters are used with default values. Run the procedure. You lot will see that the results are very like to the original Iris data set of RapidMiner repository. Please annotation that the role of all the attributes is regular in the results of the Read ARFF operator. Even the roles of 'id' and 'label' attributes are set to regular. This is and so because the ARFF files do non store information about the roles of the attributes.

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Source: https://docs.rapidminer.com/9.1/studio/operators/data_access/files/read/read_arff.html

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