Scala 如何从spark中的字符串列中提取数字部分，并在经过数学运算后更新相同的列值

我是scala spark的新手，尝试在dataframe列下面执行操作 我有一列包含字母数字值，希望根据数学运算更新这些值

    +--------------------------------------+
    |Error                                 |
    +--------------------------------------+
    |value: 0.25 Does not meet Requirements|
    |value: 0.5  Does not meet Requirements|
    |value: 0.75 Does not meet Requirements|
    |value: 0.66 Does not meet Requirements|
    |value: 0.34 Does not meet Requirements|
    +--------------------------------------+

我想执行数值操作（1-{numeric values from String}）并用新值更新列

例如，我希望输出如下所示

    +--------------------------------------+
    |Error                                 |
    +--------------------------------------+
    |value: 0.75 Does not meet Requirements|
    |value: 0.5  Does not meet Requirements|
    |value: 0.25 Does not meet Requirements|
    |value: 0.34 Does not meet Requirements|
    |value: 0.66 Does not meet Requirements|
    +--------------------------------------+

任何帮助都将不胜感激，我学习了使用正则表达式的列方法，但要执行数学运算，我没有得到任何线索

问候

---

Mahi

假设您有多个列：

+------+--------------------+
|  col1|               Error|
+------+--------------------+
| first|value: 0.25 Does ...|
|second|value: 0.5  Does ...|
| third|value: 0.75 Does ...|
|fourth|value: 0.66 Does ...|
| fifth|value: 0.34 Does ...|
+------+--------------------+

您可以使用

split

和

mkString

更新列

Error

val subtractFromOne: Double => String = number =>
  (BigDecimal(1.0) - BigDecimal(number)).toString()

val transform: String => String = s => s.split(' ') match {
  case Array(first, number, rest@_*) =>
    (Seq(first, subtractFromOne(number.toDouble)) ++ rest).mkString(" ")
  case _ => s // in case if the string is invalid we can return it unchanged
}

implicit val enc: Encoder[Row] = RowEncoder(df.schema)

df
  .map(row => Row(row(0), transform(row.getString(1))))
  .show()

将输出：

+------+--------------------------------------+
|  col1|                                 Error|
+------+--------------------------------------+
| first|value: 0.75 Does not meet Requirements|
|second|value: 0.5  Does not meet Requirements|
| third|value: 0.25 Does not meet Requirements|
|fourth|value: 0.34 Does not meet Requirements|
| fifth|value: 0.66 Does not meet Requirements|
+------+--------------------------------------+

---

BigDecimal

用于保持磅秤的高度，谢谢您的回复。只是想检查如何在第二段代码中传递col name，假设error是我的dataframe的第三列，我希望其他列也与error列更新值一起出现。