r - 是否有向量化并行 max() 和 min()？

Question

我有一个包含“a”和“b”列的data.frame。我想添加名为“high”和“low”的列，它们包含 a 列和 b 列中的最高值和最低值。

有没有办法在不循环数据帧中的行的情况下执行此操作？

编辑:这是针对 OHLC 数据，因此高列和低列应包含同一行上 a 和 b 之间的最高和最低元素，而不是整个列中的最高和最低元素。抱歉，如果措辞不当。

Answer 1

听起来您正在寻找 pmax 和 pmin(“并行”最大/分钟):

Extremes                 package:base                  R Documentation

Maxima and Minima

Description:

     Returns the (parallel) maxima and minima of the input values.

Usage:

     max(..., na.rm = FALSE)
     min(..., na.rm = FALSE)

     pmax(..., na.rm = FALSE)
     pmin(..., na.rm = FALSE)

     pmax.int(..., na.rm = FALSE)
     pmin.int(..., na.rm = FALSE)

Arguments:

     ...: numeric or character arguments (see Note).

   na.rm: a logical indicating whether missing values should be
          removed.

Details:

     ‘pmax’ and ‘pmin’ take one or more vectors (or matrices) as
     arguments and return a single vector giving the ‘parallel’ maxima
     (or minima) of the vectors.  The first element of the result is
     the maximum (minimum) of the first elements of all the arguments,
     the second element of the result is the maximum (minimum) of the
     second elements of all the arguments and so on.  Shorter inputs
     are recycled if necessary.  ‘attributes’ (such as ‘names’ or
     ‘dim’) are transferred from the first argument (if applicable).