从dataframe创建数组包含tow列

时间:2018-03-21 20:08:23

标签: arrays scala apache-spark dataframe explode

我有架构的数据框

    root
       |-- _id: long (nullable = true)
       |-- data: array (nullable = true)
             |-- element: struct (containsNull = true)
                |    |    |-- k: string (nullable = true)
                |    |    |-- v: string (nullable = true)
       |-- c : string (nullable = true)

df.show(5)

   ---------------------------------------
   _id  |  data                                                             |c
   1    |[[key1,key2,key3,key4,key5],[value1,value2,value3,value4,value5]]  |c1
   -----------------------------------------------------------------------------
   2    |[ [key1,key3,key2,key6],[value11,value31,value2,value61] ]         |c2
   -----------------------------------------------------------------------------
   3    | [[key7,key1,key3,key8,key9],[value7,value1,value3,value8,value91]]|c3
   -----------------------------------------------------------------------------
   4    |[key3,key2,key4,key5,key10],[value32,value23,value43,value10]]     |c4
   ------------------------------------------------------------------------------
   5    |[[key1 ,key2,key4,key10],[value1,value23,value42,value101]]        |c1
   .
   .
   .
   .       

我想知道是否可以获得此结果以及我必须如何进行

  _id|key1   |key2   |key3   |key4   |key5   |key6   |key7   |key8   |key9  |key10 ...
    1|value1 |value2 |value3 |value4 |value5 |       |       |       |      |
    ----------------------------------------------------------------------------
    2|value11|value2 |value31 |      |       |value6 |       |       |     
    ---------------------------------------------------------------------
    3|value1 |       |value3  |      |       |       |value7 |value8 |value91|
    ----------------------------------------------------------------------------    
    4|       |value23|value32|value43|       |       |       |        |value10
     ---------------------------------------------------------------------------
    5|value1 |value23|       |value42|       |       |       |       |       |value101
    .
    .

我试图使用爆炸,但我没有得到结果,我也尝试从第一个拖曳列构建一个阵列,但似乎很难。

1 个答案:

答案 0 :(得分:0)

您需要将此数据框映射到每行包含数据的数据框,然后您可以使用适当的列名创建新的数据框

这应该指向正确的方向......

column_names = df.select("data").collect()[0][0]
data_df = map(lambda x: x[1],df.select("data").collect())
data_par = sc.parallelize(data_df)
new_df = spark.createDataFrame(data_par, column_names, 0.1)