主页 / coding / 问题 / 79450026
Accepted
vikrant rana
Asked: 2025-02-19 09:59:14 +0800 CST

附加到空的 Seq[String]

  • 772

我试图将一个附加Seq[String]到现有的空Seq[String]

var enrichmentColumnsList: Seq[String] = Seq.empty
datasetEnricherConf.map(u => u.columnMappingsConf).foreach {
  columnMappingConf =>
    for (i <- 0 to columnMappingConf.size) {
      var cond = columnMappingConf.map(_.destColumnName)
      println(s"cond:$cond")
      enrichmentColumnsList= cond
    }
}


println(s"enrichmentColumnsList:$enrichmentColumnsList")

cond:List(NODE)
cond:List(NODE)
cond:List(NODE_temp, NETWORK, SITETYPE, STATEORPROVINCE, DISTRICT, CLUSTER, REGION)
cond:List(NODE_temp, NETWORK, SITETYPE, STATEORPROVINCE, DISTRICT, CLUSTER, REGION)
cond:List(NODE_temp, NETWORK, SITETYPE, STATEORPROVINCE, DISTRICT, CLUSTER, REGION)
cond:List(NODE_temp, NETWORK, SITETYPE, STATEORPROVINCE, DISTRICT, CLUSTER, REGION)
cond:List(NODE_temp, NETWORK, SITETYPE, STATEORPROVINCE, DISTRICT, CLUSTER, REGION)
cond:List(NODE_temp, NETWORK, SITETYPE, STATEORPROVINCE, DISTRICT, CLUSTER, REGION)
cond:List(NODE_temp, NETWORK, SITETYPE, STATEORPROVINCE, DISTRICT, CLUSTER, REGION)
cond:List(NODE_temp, NETWORK, SITETYPE, STATEORPROVINCE, DISTRICT, CLUSTER, REGION)
enrichmentColumnsList:List(NODE_temp, NETWORK, SITETYPE, STATEORPROVINCE, DISTRICT, CLUSTER, REGION)

它使用列表中的最后一次出现来初始化它。

我期望的是下面这样的情况：

enrichmentColumnsList:List(NODE,NODE_temp, NETWORK, SITETYPE, STATEORPROVINCE, DISTRICT, CLUSTER, REGION)
scala

1 个回答

  1. Best Answer

    您可以使用以下代码以更实用的方式（Scala 鼓励的方式）实现您想要的效果：

    val enrichmentColumnsList: Seq[String] =
  datasetEnricherConf
    // "flatMap" because columnMappingsConf is itself a Sequence/Iterable
    .flatMap(_.columnMappingsConf) 
    // As opposed to here where we can just use "map"
    .map(_.destColumnName)

    特别注意，我们没有使用可变数据（var）并且没有循环。

    • 3

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