Sample script to convert an CSV / Excel into RDF SKOS-XL format

csv2skosxl.php

<?php
/**
 * Sample script to convert an CSV (ie. exported form MS Excel file) into
 * RDF SKOSXL format.
 *
 * @file csv2skosxl.php
 * @license Licensed under WTFPL (http://www.wtfpl.net/txt/copying/)
 * @author Cristian Romanescu <[email protected]>
 */

if ($argc != 4) {
  echo "Usage: php csv2skosxl.php http://your.base.uri/terms input.csv output.xml" . PHP_EOL;
  exit(-1);
}

$baseUri = $argv[1];
$csvFile = $argv[2];
$xmlFile = $argv[3];

CSV2SkosXLConverter::exportToXML($baseUri, $csvFile, $xmlFile);

/**
 * Class CSV2RDFConverter takes CSV file as input and writes SKOSXL RDF format.
 * CSV has the following columns:
 *  - column 1: (REQUIRED) ID of the concept, ie. a slug - see example below
 *  - column 2: (REQUIRED) Term in english
 *  - column 3: (OPTIONAL) Broader concept, use corresponding ID from column 1
 *  - column 4: (OPTIONAL) Concept definition
 *  - column 5: (OPTIONAL) Note (skos:note)
 *  - column 6: (OPTIONAL) Identifier, non-human languages (skos:notation)
 *
 *  Example
 *
 * |concept| prefLabel| broader| definition | note | notation |
 * |cheetah| Cheetah  | mammal | Four legs  | Fast | CHEETH-01|
 * |mammal | Mammals  | animal | Warm blood |      |          |
 * |animal | Animals  |        | All animals|      |          |
 *
 * Limitations (easily overcome by toying with the script):
 *
 * 1. Only the above specified columns are supported
 * 2. prefLabel is reified in order to be loadable into VocBench tool
 * 3. No multilingual support
 */
class CSV2SkosXLConverter {

  private static $scheme = 'http://your.domain.org/terms';

  public static function exportToXML($scheme, $csvFile, $xmlFile) {
    self::$scheme = $scheme;
    $terms = self::parseFile($csvFile);
    $content = self::toXML($terms);
    file_put_contents($xmlFile, $content);
  }

  /**
   */
  static function parseFile($filename) {
    $terms = array();
    if (($handle = fopen($filename, 'r')) !== FALSE) {
      try {
        $i = 0;
        while (($row = fgetcsv($handle, 1000, ",")) !== FALSE) {
          if (!empty($row[0]) && $i++ != 0) {
            $term = new stdClass();
            $term->id = self::slugify($row[0]);
            $term->prefLabel = $row[1];
            $term->broader = !empty($row[2]) ? $row[2] : NULL;
            $term->definition = !empty($row[3]) ? $row[3] : NULL;
            $term->note = !empty($row[4]) ? $row[4] : NULL;
            $term->notation = !empty($row[5]) ? $row[5] : NULL;
            $terms[$term->id] = $term;
          }
        }
      }
      catch (Exception $e) {
        fclose($handle);
      }
    } else {
      throw new Exception('Failed to open input file');
    }

    // Remove invalid broader term (skos:Broader points to invalid concepts)
    foreach($terms as &$term) {
      if (!empty($term->broader) && !array_key_exists($term->broader, $terms)) {
        echo "Removing invalid broader term: {$term->broader}" . PHP_EOL;
        $term->broader = NULL;
      }
    }

    return $terms;
  }


  public static function toXML($terms) {
    $scheme = self::$scheme;
    // Start building up a RDF graph
    $guid = self::guid();
    $ret = array(
      <<<EOT
<?xml version="1.0" encoding="UTF-8"?>
<rdf:RDF
        xmlns="$scheme"
        xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
        xmlns:owl="http://www.w3.org/2002/07/owl#"
        xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
        xmlns:dct="http://purl.org/dc/terms/"
        xmlns:skos="http://www.w3.org/2004/02/skos/core#"
        xmlns:skosxl="http://www.w3.org/2008/05/skos-xl#"
        xmlns:ann="http://art.uniroma2.it/ontologies/annotation#">

    <rdf:Description rdf:about="$scheme">
        <rdf:type rdf:resource="http://www.w3.org/2004/02/skos/core#ConceptScheme" />
        <skosxl:prefLabel rdf:resource="$scheme/xl-$guid" />
    </rdf:Description>
    <rdf:Description rdf:about="$scheme/xl-$guid">
        <rdf:type rdf:resource="http://www.w3.org/2008/05/skos-xl#Label" />
        <skosxl:literalForm xml:lang="en">Your beloved thesaurus</skosxl:literalForm>
    </rdf:Description>
EOT
    );
    foreach ($terms as $term) {
      $uri = $scheme . '/' . $term->id;
      $output  = "    <rdf:Description rdf:about=\"$uri\">" . PHP_EOL;
      $output .= "        <rdf:type rdf:resource=\"http://www.w3.org/2004/02/skos/core#Concept\" />" . PHP_EOL;
      $output .= "        <skos:inScheme rdf:resource=\"$scheme\" />" . PHP_EOL;
      // Make it root concept
      if (empty($term->broader)) {
        $output .= "        <skos:topConceptOf rdf:resource=\"$scheme\" />" . PHP_EOL;
      }

      // skos:note
      if (!empty($term->note)) {
        $output .= "        <skos:note>{$term->note}</skos:note>" . PHP_EOL;
      }

      // skos:notation
      if (!empty($term->notation)) {
        $output .= "        <skos:notation>{$term->notation}</skos:notation>" . PHP_EOL;
      }

      // skos:definition
      $definition = '';
      if (!empty($term->definition)) {
        $definition_uri = self::addDefinition($term, $definition);
        $output .= "        <skos:definition rdf:resource=\"{$definition_uri}\" />" . PHP_EOL;
      }

      // skos:prefLabel
      $prefLabel = '';
      $label_uri = self::addReifiedPrefLabel($term, $prefLabel);
      $output .= "        <skosxl:prefLabel rdf:resource=\"$label_uri\" />" . PHP_EOL;
      $output .= "    </rdf:Description>" . PHP_EOL;
      if (!empty($prefLabel)) {
        $output .= PHP_EOL . $prefLabel;
      }

      $output .= $definition;

      // skos:broader
      if (!empty($term->broader)) {
        $b_uri = $scheme . '/' . $term->broader;
        $output .= PHP_EOL;
        $output .= "    <rdf:Description rdf:about=\"$uri\">" . PHP_EOL;
        $output .= "        <skos:broader rdf:resource=\"$b_uri\" />" . PHP_EOL;
        $output .= "    </rdf:Description>" . PHP_EOL;
      }
      $ret[] = $output;
    }
    $ret[] = '</rdf:RDF>';
    return implode($ret, PHP_EOL);
  }


  public static function addDefinition($term, &$buffer, $language = 'en') {
    $uri = self::$scheme . '/def_' . $term->id;
    $description = self::xml_entities($term->definition);
    $buffer .= "    <rdf:Description rdf:about=\"$uri\">" . PHP_EOL;
    $buffer .= "        <rdf:value xml:lang=\"$language\">$description</rdf:value>" . PHP_EOL;
    $buffer .= "    </rdf:Description>" . PHP_EOL;
    return $uri;
  }

  public static function addReifiedPrefLabel($term, &$buffer, $language = 'en') {
    $uri = self::$scheme . '/xl_' . $language . '_' . $term->id;
    $title = self::xml_entities($term->prefLabel);
    $buffer .= "    <rdf:Description rdf:about=\"$uri\">" . PHP_EOL;
    $buffer .= "        <rdf:type rdf:resource=\"http://www.w3.org/2008/05/skos-xl#Label\" />" . PHP_EOL;
    $buffer .= "        <skosxl:literalForm xml:lang=\"$language\">$title</skosxl:literalForm>" . PHP_EOL;
    $buffer .= "    </rdf:Description>" . PHP_EOL;
    return $uri;
  }

  static function xml_entities($string) {
    return strtr(
      $string,
      array(
        "<" => "&lt;",
        ">" => "&gt;",
        '"' => "&quot;",
        "'" => "&apos;",
        "&" => "&amp;",
      )
    );
  }

  static function slugify($text) {
    // replace non letter or digits by -
    $text = preg_replace('~[^\\pL\d]+~u', '-', $text);
    // trim
    $text = trim($text, '-');
    // transliterate
    $text = iconv('utf-8', 'us-ascii//TRANSLIT', $text);
    // lowercase
    $text = strtolower($text);
    // remove unwanted characters
    $text = preg_replace('~[^-\w]+~', '', $text);
    if (empty($text)) {
      return 'n-a';
    }
    return $text;
  }

  static function guid($lowercase = TRUE) {
    $charid = strtoupper(md5(uniqid(rand(), TRUE)));
    $hyphen = chr(45);// "-"
    $uuid = substr($charid, 0, 8) . $hyphen
            . substr($charid, 8, 4) . $hyphen
            . substr($charid, 12, 4) . $hyphen
            . substr($charid, 16, 4) . $hyphen
            . substr($charid, 20, 12);
    return $lowercase ? strtolower($uuid) : $uuid;
  }
}

Instructions

Requires to have PHP 5.x installed on the system

1. Open your Excel file and save as Comma Separated Values, make sure you use "," as separator and quote cells with double quotes ("). Tested and works fine with LibreOffice or OpenOffice.
2. Save the script above in the same folder with the CSV file

1. Run the converter like this: php csv2skosxl.php http://thesaurus.us.org/glossary/terms input.csv output.xml

Excel file must have the following format:

|concept| prefLabel| broader| definition | note | notation |
|cheetah| Cheetah  | mammal | Four legs  | Fast | CHEETH-01|
|mammal | Mammals  | animal | Warm blood |      |          |
|animal | Animals  |        | All animals|      |          |