Add support for validating languages

Will validate against ISO 639-2 or ISO 639-3 depending on how long
the language field is. Otherwise will return that the language is
invalid.

Does not currently have any support for generic values like "Other".

README.md

@@ -8,6 +8,7 @@ Requires Python 3.6 or greater. CSV and Excel support comes from the [Pandas](ht
 - Read/write CSV files
 - Read Excel files
 - Validate dates, ISSNs, ISBNs, and multi-value separators ("||")
+- Validate languages against ISO 639-2 and ISO 639-3
 - Fix leading, trailing, and excessive whitespace
 - Fix invalid multi-value separators (`|`) using `--unsafe-fixes`
 - Remove unnecessary Unicode like [non-breaking spaces](https://en.wikipedia.org/wiki/Non-breaking_space), [replacement characters](https://en.wikipedia.org/wiki/Specials_(Unicode_block)#Replacement_character), etc

csv_metadata_quality/app.py

@@ -43,6 +43,11 @@ def main(argv):
         # Fix: duplicate metadata values
         df[column] = df[column].apply(fix.duplicates)
 
+        # Check: invalid language
+        match = re.match(r'^.*?language.*$', column)
+        if match is not None:
+            df[column] = df[column].apply(check.language)
+
         # Check: invalid ISSN
         match = re.match(r'^.*?issn.*$', column)
         if match is not None:

csv_metadata_quality/check.py

@@ -149,3 +149,43 @@ def suspicious_characters(field):
             print(f'Suspicious character: {field}')
 
     return field
+
+
+def language(field):
+    """Check if a language is valid ISO 639-2 or ISO 639-3.
+
+    Prints the value if it is invalid.
+    """
+
+    from iso639 import languages
+
+    # Skip fields with missing values
+    if pd.isna(field):
+        return
+
+    # need to handle "Other" values here...
+
+    # Try to split multi-value field on "||" separator
+    for value in field.split('||'):
+
+        # After splitting, check if language value is 2 or 3 characters so we
+        # can check it against ISO 639-2 or ISO 639-3 accordingly. In iso-639
+        # library ISO 639-2 is "part1" and ISO 639-3 is "part3".
+        if len(value) == 2:
+            try:
+                languages.get(part1=value)
+            except KeyError:
+                print(f'Invalid ISO 639-2 language: {value}')
+
+                pass
+        elif len(value) == 3:
+            try:
+                languages.get(part3=value)
+            except KeyError:
+                print(f'Invalid ISO 639-3 language: {value}')
+
+                pass
+        else:
+            print(f'Invalid language: {value}')
+
+    return field

data/test.csv

@@ -1,15 +1,18 @@
-dc.contributor.author,birthdate,dc.identifier.issn,dc.identifier.isbn
- Leading space,2019-07-29,,
-Trailing space ,2019-07-29,,
-Excessive  space,2019-07-29,,
-Miscellaenous ||whitespace | issues ,2019-07-29,,
-Duplicate||Duplicate,2019-07-29,,
-Invalid ISSN,2019-07-29,2321-2302,
-Invalid ISBN,2019-07-29,,978-0-306-40615-6
-Multiple valid ISSNs,2019-07-29,0378-5955||0024-9319,
-Multiple valid ISBNs,2019-07-29,,99921-58-10-7||978-0-306-40615-7
-Invalid date,2019-07-260,,
-Multiple dates,2019-07-26||2019-01-10,,
-Invalid multi-value separator,,0378-5955|0024-9319,
-Unnecessary Unicode​,2019-07-29,,
-Suspicious character||foreˆt,2019-07-29,,
+dc.contributor.author,birthdate,dc.identifier.issn,dc.identifier.isbn,dc.language.iso
+ Leading space,2019-07-29,,,
+Trailing space ,2019-07-29,,,
+Excessive  space,2019-07-29,,,
+Miscellaenous ||whitespace | issues ,2019-07-29,,,
+Duplicate||Duplicate,2019-07-29,,,
+Invalid ISSN,2019-07-29,2321-2302,,
+Invalid ISBN,2019-07-29,,978-0-306-40615-6,
+Multiple valid ISSNs,2019-07-29,0378-5955||0024-9319,,
+Multiple valid ISBNs,2019-07-29,,99921-58-10-7||978-0-306-40615-7,
+Invalid date,2019-07-260,,,
+Multiple dates,2019-07-26||2019-01-10,,,
+Invalid multi-value separator,,0378-5955|0024-9319,,
+Unnecessary Unicode​,2019-07-29,,,
+Suspicious character||foreˆt,2019-07-29,,,
+Invalid ISO 639-2 language,2019-07-29,,,jp
+Invalid ISO 639-3 language,2019-07-29,,,chi
+Invalid language,2019-07-29,,,Span

tests/test_check.py

@@ -116,3 +116,56 @@ def test_check_suspicious_characters(capsys):
 
     captured = capsys.readouterr()
     assert captured.out == f'Suspicious character: {value}\n'
+
+
+def test_check_valid_iso639_2_language():
+    '''Test valid ISO 639-2 language.'''
+
+    value = 'ja'
+
+    result = check.language(value)
+
+    assert result == value
+
+
+def test_check_valid_iso639_3_language():
+    '''Test invalid ISO 639-3 language.'''
+
+    value = 'eng'
+
+    result = check.language(value)
+
+    assert result == value
+
+
+def test_check_invalid_iso639_2_language(capsys):
+    '''Test invalid ISO 639-2 language.'''
+
+    value = 'jp'
+
+    check.language(value)
+
+    captured = capsys.readouterr()
+    assert captured.out == f'Invalid ISO 639-2 language: {value}\n'
+
+
+def test_check_invalid_iso639_3_language(capsys):
+    '''Test invalid ISO 639-3 language.'''
+
+    value = 'chi'
+
+    check.language(value)
+
+    captured = capsys.readouterr()
+    assert captured.out == f'Invalid ISO 639-3 language: {value}\n'
+
+
+def test_check_invalid_language(capsys):
+    '''Test invalid language.'''
+
+    value = 'Span'
+
+    check.language(value)
+
+    captured = capsys.readouterr()
+    assert captured.out == f'Invalid language: {value}\n'