我有以下DataFrame:
root
|-- sents: array (nullable = false)
| |-- element: integer (containsNull = true)
|-- metadata: array (nullable = true)
| |-- element: float (containsNull = true)
+----------+---------------------+
|sents |metadata |
+----------+---------------------+
|[1, -1, 0]|[0.4991, 0.5378, 0.0]|
|[-1] |[0.6281] |
|[-1] |[0.463] |
+----------+---------------------+
我想动态地将每个数组项扩展到其自己的列,以便其外观如下:
+--------+--------+--------+-----------+-----------+-----------+
|sents[0]|sents[1]|sents[2]|metadata[0]|metadata[1]|metadata[2]|
+--------+--------+--------+-----------+-----------+-----------+
| 1| -1| 0| 0.4991| 0.5378| 0.0|
| -1| null| null| 0.6281| null| null|
| -1| null| null| 0.463| null| null|
+--------+--------+--------+-----------+-----------+-----------+
但是在结构化流传输中,动态处理存在很多限制:
我尝试了以下操作:
numcol = df.withColumn('phrasesNum', F.size('sents')).agg(F.max('phrasesNum')).head()
df = df.select(*[F.col('sents')[i] for i in range(numcol[0])],*[F.col('metadata')[i] for i in range(numcol[0])])
也:
df_sizes = df.select(F.size('sents').alias('sents'))
df_max = df_sizes.agg(F.max('sents'))
nb_columns = df_max.collect()[0][0]
d = c.select(*[F.map_values(c['metadata'][i]).getItem(0).alias('confidenceIntervals'+"{}".format(j)).cast(DoubleType()) for i,j in enumerate(range(F.size('sents')))],
*[c['sents'][i].alias('phraseSents'+"{}".format(j)).cast(IntegerType()) for i,j in enumerate(range(nb_columns))])
但是我不能在结构化流中使用.head(),.collect()或.take()之类的东西来创建表示要动态创建的列数的数字变量。有任何想法吗??
感谢所有人
您可以尝试使用一个返回每列的最大大小的函数(我使用了first
而不是collect
),然后将每个数组列拆分为多列并选择它们:
def f(x):
r = df.select(F.max(F.size(x)).alias("col")).first().col
return [df[x][i] for i in range(r)]
l = [f(column) for column in df.columns] #change df.columns to specific list you may have
df.select(*[b for a in l for b in a]).show()
+--------+--------+--------+-----------+-----------+-----------+
|sents[0]|sents[1]|sents[2]|metadata[0]|metadata[1]|metadata[2]|
+--------+--------+--------+-----------+-----------+-----------+
| 1| -1| 0| 0.4991| 0.5378| 0.0|
| -1| null| null| 0.6281| null| null|
| -1| null| null| 0.463| null| null|
+--------+--------+--------+-----------+-----------+-----------+