chaneg dtype of pysaprk df code example

Example: pyspark cast column to long

changedTypedf = joindf.withColumn("label", joindf["show"].cast("double"))
// types = ['BinaryType', 'BooleanType', 'ByteType', 'DateType', 
//          'DecimalType', 'DoubleType', 'FloatType', 'IntegerType', 
//          'LongType', 'ShortType', 'StringType', 'TimestampType']