如何解决这个问题？ RuntimeError：字典在迭代期间改变了大小

Question

当我使用in a函数将项目添加到字典时，它会出现此错误：

inv = { "rope": 1, "torch": 6, "gold coin": 42, "dagger": 1, "arrow": 12 }
dragonLoot = ['gold coin', 'dagger', 'gold coin', 'gold coin', 'ruby']
def AddInventory(invloop, lst):
  for item in lst:
    for k,v in invloop.items():
      if item == k:
        v += 1
      else:
        invloop[item] = 1
  return(invloop)
inv = AddInventory(inv, dragonLoot)

Answer 1

确实，您不应该在循环上添加项目到库存。更重要的是，你不需要那个内循环，因为字典的优势在于你可以通过密钥直接访问：你可以使用{{1}来测试它是否有密钥运算符。

所以这样做：

import java.io.File
import java.io.FileInputStream
import java.io.IOException
import java.util.ArrayList
import java.util.HashSet
import java.util.List
import java.util.Set
import org.apache.hadoop.conf.Configuration
import org.apache.hadoop.hbase._
import org.apache.hadoop.hbase.client._
import org.apache.log4j.Logger
import HBaseImporter._

object HBaseImporter {

  def main(args: Array[String]): Unit = {
    if (args.length < 2 || args.length > 3) {
      println(
        "Usage: HBaseImporter <tablename> <csv file path> [<key field name>]")
    }
    val tableName: String = args(0)
    val f: File = new File(args(1))
    var keyColumn: String = null
    if (args.length > 2) {
      keyColumn = args(2)
    }
    val importer: HBaseImporter = new HBaseImporter(tableName)
    importer.importCSV(f, keyColumn)
  }

}

class HBaseImporter(var tableName: String) extends HBaseImportExport {
  var admin: HBaseAdmin = _
  var config: Configuration = _
  var families: Set[String] = new HashSet[String]()
  var columns: List[HBaseCol] = new ArrayList[HBaseCol]()
  var keyPosition: Int = -1

  def init(): Unit = {
    config = HBaseConfiguration.create()
    admin = new HBaseAdmin(config)
  }

  private def deleteTable(): Unit = {
    try {
      admin.disableTable(tableName)
      admin.deleteTable(tableName)
    } catch {
      case e: Exception => {}

    }
  }

  private def createTable(): Unit = {
    val desc: HTableDescriptor = new HTableDescriptor(tableName)
    admin.createTable(desc)
    admin.disableTable(tableName)
    for (family <- families) {
      val cf1: HColumnDescriptor = new HColumnDescriptor(family)
      admin.addColumn(tableName, cf1)
    }
    admin.enableTable(tableName)
  }

  private def analyzeHeaders(headers: Array[String], keyColumn: String): Unit = {
    columns.clear()
    families.clear()
    var col: Int = 0
    for (header <- headers) {
      var family: String = DEFAULT_COLUMN_FAMILY
      var qualifier: String = header
      var pos: Int = 0
      if ((pos = header.indexOf(":")) > 0) {
        family = header.substring(0, pos)
        qualifier = header.substring(pos + 1)
      }
      columns.add(new HBaseCol(family, qualifier))
      families.add(family)
      if (header == keyColumn) {
        keyPosition = col
      }
      { col += 1; col - 1 }
    }
  }

  private def loadData(cis: CsvInputStream): Unit = {
    val table: HTable = new HTable(config, tableName)
    var vals: Array[String] = cis.readLine()
    val logger: Logger = org.apache.log4j.Logger.getLogger(this.getClass)
    var counter: Int = 0
    var rowId: String = ""
    while (vals != null) {
      rowId =
        if (keyPosition >= 0 && keyPosition < vals.length) vals(keyPosition)
        else "r" + counter
      val put: Put = new Put(rowId.getBytes("UTF-8"))
      var col: Int = 0
      for (column <- columns) {
        if (col >= vals.length) {
//break
        }
        put.add(column.family.getBytes("UTF-8"),
                column.qualifier.getBytes,
                vals(col).getBytes)
        col += 1
      }
      table.put(put)
      vals = cis.readLine()
      counter += 1
      if (counter % 10000 == 0) {
        logger.info("Imported " + counter + " records")
      }
    }
    cis.close()
  }

  /**
    * import CSV to an HBase table
    *
    * @param tableName name of the table in HBase
    * @param csvFile a file
    *
    * @throws IOException
    */
  def importCSV(csvFile: File, keyColumn: String): Unit = {
    init()
    val fis: FileInputStream = new FileInputStream(csvFile)
    val cis: CsvInputStream = new CsvInputStream(fis)
    // read field names from the first line of the csv file
    analyzeHeaders(cis.readLine(), keyColumn)
    deleteTable()
    createTable()
    loadData(cis)
    cis.close()
  }

}