code: def summary(self, *statistics):
          
          if len(statistics) == 1 and isinstance(statistics[0], list):
              statistics = statistics[0]
          jdf = self._jdf.summary(self._jseq(statistics))
          return DataFrame(jdf, self.sql_ctx)
docs: Computes specified statistics for numeric and string columns. Available statistics are:
          - count
          - mean
          - stddev
          - min
          - max
          - arbitrary approximate percentiles specified as a percentage (eg, 75%)
  
          If no statistics are given, this function computes count, mean, stddev, min,
          approximate quartiles (percentiles at 25%, 50%, and 75%), and max.
  
          .. note:: This function is meant for exploratory data analysis, as we make no
              guarantee about the backward compatibility of the schema of the resulting DataFrame.
  
          >>> df.summary().show()
          +-------+------------------+-----+
          |summary|               age| name|
          +-------+------------------+-----+
          |  count|                 2|    2|
          |   mean|               3.5| null|
          | stddev|2.1213203435596424| null|
          |    min|                 2|Alice|
          |    25%|                 2| null|
          |    50%|                 2| null|
          |    75%|                 5| null|
          |    max|                 5|  Bob|
          +-------+------------------+-----+
  
          >>> df.summary("count", "min", "25%", "75%", "max").show()
          +-------+---+-----+
          |summary|age| name|
          +-------+---+-----+
          |  count|  2|    2|
          |    min|  2|Alice|
          |    25%|  2| null|
          |    75%|  5| null|
          |    max|  5|  Bob|
          +-------+---+-----+
  
          To do a summary for specific columns first select them:
  
          >>> df.select("age", "name").summary("count").show()
          +-------+---+----+
          |summary|age|name|
          +-------+---+----+
          |  count|  2|   2|
          +-------+---+----+
  
          See also describe for basic statistics.