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From: gatorsmile <git@git.apache.org>
To: reviews@spark.apache.org
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References: <git-pr-17733-spark@git.apache.org>
In-Reply-To: <git-pr-17733-spark@git.apache.org>
Subject: [GitHub] spark pull request #17733: [SPARK-20425][SQL] Support a vertical display mod...
Content-Type: text/plain
Message-Id: <20170426055759.BE6A3DFBDA@git1-us-west.apache.org>
Date: Wed, 26 Apr 2017 05:57:59 +0000 (UTC)
archived-at: Wed, 26 Apr 2017 05:58:02 -0000

Github user gatorsmile commented on a diff in the pull request:

    https://github.com/apache/spark/pull/17733#discussion_r113370773
  
    --- Diff: sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala ---
    @@ -277,43 +279,73 @@ class Dataset[T] private[sql](
     
         val sb = new StringBuilder
         val numCols = schema.fieldNames.length
    +    // We set a minimum column width at '3'
    +    val minimumColWidth = 3
     
    -    // Initialise the width of each column to a minimum value of '3'
    -    val colWidths = Array.fill(numCols)(3)
    +    if (!vertical) {
    +      // Initialise the width of each column to a minimum value
    +      val colWidths = Array.fill(numCols)(minimumColWidth)
     
    -    // Compute the width of each column
    -    for (row <- rows) {
    -      for ((cell, i) <- row.zipWithIndex) {
    -        colWidths(i) = math.max(colWidths(i), cell.length)
    -      }
    -    }
    -
    -    // Create SeparateLine
    -    val sep: String = colWidths.map("-" * _).addString(sb, "+", "+", "+\n").toString()
    -
    -    // column names
    -    rows.head.zipWithIndex.map { case (cell, i) =>
    -      if (truncate > 0) {
    -        StringUtils.leftPad(cell, colWidths(i))
    -      } else {
    -        StringUtils.rightPad(cell, colWidths(i))
    +      // Compute the width of each column
    +      for (row <- rows) {
    +        for ((cell, i) <- row.zipWithIndex) {
    +          colWidths(i) = math.max(colWidths(i), cell.length)
    +        }
           }
    -    }.addString(sb, "|", "|", "|\n")
     
    -    sb.append(sep)
    +      // Create SeparateLine
    +      val sep: String = colWidths.map("-" * _).addString(sb, "+", "+", "+\n").toString()
     
    -    // data
    -    rows.tail.map {
    -      _.zipWithIndex.map { case (cell, i) =>
    +      // column names
    +      rows.head.zipWithIndex.map { case (cell, i) =>
             if (truncate > 0) {
    -          StringUtils.leftPad(cell.toString, colWidths(i))
    +          StringUtils.leftPad(cell, colWidths(i))
             } else {
    -          StringUtils.rightPad(cell.toString, colWidths(i))
    +          StringUtils.rightPad(cell, colWidths(i))
             }
           }.addString(sb, "|", "|", "|\n")
    -    }
     
    -    sb.append(sep)
    +      sb.append(sep)
    +
    +      // data
    +      rows.tail.foreach {
    +        _.zipWithIndex.map { case (cell, i) =>
    +          if (truncate > 0) {
    +            StringUtils.leftPad(cell.toString, colWidths(i))
    +          } else {
    +            StringUtils.rightPad(cell.toString, colWidths(i))
    +          }
    +        }.addString(sb, "|", "|", "|\n")
    +      }
    +
    +      sb.append(sep)
    +    } else {
    +      // Extended display mode enabled
    +      val fieldNames = rows.head
    +      val dataRows = rows.tail
    +
    +      // Compute the width of field name and data columns
    +      val fieldNameColWidth = fieldNames.foldLeft(minimumColWidth) { case (curMax, fieldName) =>
    +        math.max(curMax, fieldName.length)
    +      }
    +      val dataColWidth = dataRows.foldLeft(minimumColWidth) { case (curMax, row) =>
    +        math.max(curMax, row.map(_.length).reduceLeftOption[Int] { case (cellMax, cell) =>
    +          math.max(cellMax, cell)
    +        }.getOrElse(0))
    +      }
    +
    +      dataRows.zipWithIndex.foreach { case (row, i) =>
    --- End diff --
    
    When no row exists, we at least need to output the column names.
    
    ```Scala
    df.limit(0).show(20, 0, true)
    ```


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