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author | Sean Owen <sowen@cloudera.com> | 2016-08-10 10:14:43 +0100 |
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committer | Sean Owen <sowen@cloudera.com> | 2016-08-10 10:14:43 +0100 |
commit | 0578ff9681edbaab4ae68f67272dc3d4d890d53b (patch) | |
tree | d54b571ca32c769dbcfdf116aaf51a178c2785ae /python/pyspark | |
parent | eca58755fbbc11937b335ad953a3caff89b818e6 (diff) | |
download | spark-0578ff9681edbaab4ae68f67272dc3d4d890d53b.tar.gz spark-0578ff9681edbaab4ae68f67272dc3d4d890d53b.tar.bz2 spark-0578ff9681edbaab4ae68f67272dc3d4d890d53b.zip |
[SPARK-16324][SQL] regexp_extract should doc that it returns empty string when match fails
## What changes were proposed in this pull request?
Doc that regexp_extract returns empty string when regex or group does not match
## How was this patch tested?
Jenkins test, with a few new test cases
Author: Sean Owen <sowen@cloudera.com>
Closes #14525 from srowen/SPARK-16324.
Diffstat (limited to 'python/pyspark')
-rw-r--r-- | python/pyspark/sql/functions.py | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/python/pyspark/sql/functions.py b/python/pyspark/sql/functions.py index 8a01805ec8..4ea83e24bb 100644 --- a/python/pyspark/sql/functions.py +++ b/python/pyspark/sql/functions.py @@ -1440,11 +1440,15 @@ def split(str, pattern): @ignore_unicode_prefix @since(1.5) def regexp_extract(str, pattern, idx): - """Extract a specific(idx) group identified by a java regex, from the specified string column. + """Extract a specific group matched by a Java regex, from the specified string column. + If the regex did not match, or the specified group did not match, an empty string is returned. >>> df = spark.createDataFrame([('100-200',)], ['str']) >>> df.select(regexp_extract('str', '(\d+)-(\d+)', 1).alias('d')).collect() [Row(d=u'100')] + >>> df = spark.createDataFrame([('foo',)], ['str']) + >>> df.select(regexp_extract('str', '(\d+)', 1).alias('d')).collect() + [Row(d=u'')] >>> df = spark.createDataFrame([('aaaac',)], ['str']) >>> df.select(regexp_extract('str', '(a+)(b)?(c)', 2).alias('d')).collect() [Row(d=u'')] |