liying919 commented on a change in pull request #12012:
URL: https://github.com/apache/flink/pull/12012#discussion_r421432745
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File path: docs/training/etl.zh.md
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@@ -103,9 +91,7 @@ public static class Enrichment implements
MapFunction<TaxiRide, EnrichedRide> {
### `flatmap()`
-A `MapFunction` is suitable only when performing a one-to-one transformation:
for each and every
-stream element coming in, `map()` will emit one transformed element.
Otherwise, you will want to use
-`flatmap()`
+`MapFunction` 只适用于一对一的转换：对每个进入算子的流元素，`map()` 将发射一个转换后的元素。对于除此以外的场景，你将要使用
`flatmap()`。
Review comment:
这里我改成“仅输出”吧
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File path: docs/training/etl.zh.md
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@@ -131,36 +117,27 @@ public static class NYCEnrichment implements
FlatMapFunction<TaxiRide, EnrichedR
}
{% endhighlight %}
-With the `Collector` provided in this interface, the `flatmap()` method can
emit as many stream
-elements as you like, including none at all.
+使用接口中提供的 `Collector` ，`flatmap()` 可以发射你想要的任意数量的元素，也可以一个都不发。
Review comment:
这里我改成“输出”吧
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