【发布时间】：2018-06-20 11:00:36
【问题描述】：
我有一个基础数据集，其中一列具有空值和非空值。 所以我这样做：
val nonTrained_ds = base_ds.filter(col("col_name").isNull)
val trained_ds = base_ds.filter(col("col_name").isNotNull)
当我打印出来时，我清楚地分开了行。但是当我这样做时，
val combined_ds = nonTrained_ds.union(trained_ds)
我从nonTrained_ds 得到重复的行记录，奇怪的是，来自trained_ds 的行不再在合并的ds 中。
为什么会这样？
trained_ds 的值为：
+----------+----------------+
|unique_no | running_id|
+----------+----------------+
|0456700001|16 |
|0456700004|16 |
|0456700007|16 |
|0456700010|16 |
|0456700013|16 |
|0456700016|16 |
|0456700019|16 |
|0456700022|16 |
|0456700025|16 |
|0456700028|16 |
|0456700031|16 |
|0456700034|16 |
|0456700037|16 |
|0456700040|16 |
|0456700043|16 |
|0456700046|16 |
|0456700049|16 |
|0456700052|16 |
|0456700055|16 |
|0456700058|16 |
|0456700061|16 |
|0456700064|16 |
|0456700067|16 |
|0456700070|16 |
+----------+----------------+
nonTrained_ds 的值为：
+----------+----------------+
|unique_no | running_id|
+----------+----------------+
|0456700002|null |
|0456700003|null |
|0456700005|null |
|0456700006|null |
|0456700008|null |
|0456700009|null |
|0456700011|null |
|0456700012|null |
|0456700014|null |
|0456700015|null |
|0456700017|null |
|0456700018|null |
|0456700020|null |
|0456700021|null |
|0456700023|null |
|0456700024|null |
|0456700026|null |
|0456700027|null |
|0456700029|null |
|0456700030|null |
|0456700032|null |
|0456700033|null |
|0456700035|null |
|0456700036|null |
|0456700038|null |
|0456700039|null |
|0456700041|null |
|0456700042|null |
|0456700044|null |
|0456700045|null |
|0456700047|null |
|0456700048|null |
|0456700050|null |
|0456700051|null |
|0456700053|null |
|0456700054|null |
|0456700056|null |
|0456700057|null |
|0456700059|null |
|0456700060|null |
|0456700062|null |
|0456700063|null |
|0456700065|null |
|0456700066|null |
|0456700068|null |
|0456700069|null |
|0456700071|null |
|0456700072|null |
+----------+----------------+
组合ds的值为：
+----------+----------------+
|unique_no | running_id|
+----------+----------------+
|0456700002|null |
|0456700003|null |
|0456700005|null |
|0456700006|null |
|0456700008|null |
|0456700009|null |
|0456700011|null |
|0456700012|null |
|0456700014|null |
|0456700015|null |
|0456700017|null |
|0456700018|null |
|0456700020|null |
|0456700021|null |
|0456700023|null |
|0456700024|null |
|0456700026|null |
|0456700027|null |
|0456700029|null |
|0456700030|null |
|0456700032|null |
|0456700033|null |
|0456700035|null |
|0456700036|null |
|0456700038|null |
|0456700039|null |
|0456700041|null |
|0456700042|null |
|0456700044|null |
|0456700045|null |
|0456700047|null |
|0456700048|null |
|0456700050|null |
|0456700051|null |
|0456700053|null |
|0456700054|null |
|0456700056|null |
|0456700057|null |
|0456700059|null |
|0456700060|null |
|0456700062|null |
|0456700063|null |
|0456700065|null |
|0456700066|null |
|0456700068|null |
|0456700069|null |
|0456700071|null |
|0456700072|null |
|0456700002|16 |
|0456700005|16 |
|0456700008|16 |
|0456700011|16 |
|0456700014|16 |
|0456700017|16 |
|0456700020|16 |
|0456700023|16 |
|0456700026|16 |
|0456700029|16 |
|0456700032|16 |
|0456700035|16 |
|0456700038|16 |
|0456700041|16 |
|0456700044|16 |
|0456700047|16 |
|0456700050|16 |
|0456700053|16 |
|0456700056|16 |
|0456700059|16 |
|0456700062|16 |
|0456700065|16 |
|0456700068|16 |
|0456700071|16 |
+----------+----------------+
【问题讨论】：
-
能否显示重复的行和未合并的行？我猜你没有可视化整个数据集。
-
如果您查看组合数据集输出，“0456700002”值出现了两次。
-
不确定有人用“-1”标记了这个问题 - 如果它不明确，请询问清楚。如果您查看组合数据集，所有值为“16”的行都是“nonTrained_ds”中第一列的副本
-
这些是您在输入数据框中拥有的唯一数据吗？在trained_ds 和nontrained_ds 中？还是还有更多？
-
还有很多其他的列，但中间没有任何修改。我只是将数据集“A”提取到 2 个数据集中并将它们重新加入以获得数据集“A”。我正在使用 Spark 2.0
标签： scala apache-spark