在 R 编程中查找时序数据的最大值

Question

我有数据

cmpny_name Hr_Min_Sec   Price   Hr_min
A         09:15:41   7610    09:15
A         09:15:42   7632    09:15
A         09:15:43   7654    09:15
A         09:16:21   7655    09:16
A         09:16:59   7854    09:16
A         09:17:32   7453    09:17
A         09:17:42   7467    09:17
A         09:17:58   7557    09:17
A         09:18:03   7567    09:18
A         09:18:58   7659    09:18
A         09:18:59   7810    09:18

在这里，我想在每个Hr_min中找到max(Hr_Min_Sec(，并且必须将结果显示为

cmpny_name Hr_Min_Sec   Price   Hr_min
A         09:15:43   7654    09:15
A         09:16:59   7854    09:16
A         09:17:58   7557    09:17
A         09:18:59   7810    09:18

Answer 1

df1[!duplicated(df1$Hr_min, fromLast = TRUE), ]
   cmpny_name Hr_Min_Sec Price Hr_min
3           A    9:15:43  7654   9:15
5           A    9:16:59  7854   9:16
8           A    9:17:58  7557   9:17
11          A    9:18:59  7810   9:18

修改自 https://stackoverflow.com/a/23461294/3242130

Answer 2

这是一个data.table的解决方案

library("data.table")
dt <- fread(
  'cmpny_name Hr_Min_Sec   Price   Hr_min
A         09:15:41   7610    09:15
A         09:15:42   7632    09:15
A         09:15:43   7654    09:15
A         09:16:21   7655    09:16
A         09:16:59   7854    09:16
A         09:17:32   7453    09:17
A         09:17:42   7467    09:17
A         09:17:58   7557    09:17
A         09:18:03   7567    09:18
A         09:18:58   7659    09:18
A         09:18:59   7810    09:18')
dt[, .SD[max(Hr_Min_Sec)==Hr_Min_Sec,], by=Hr_min] # or
dt[, .SD[.N], by=Hr_min] # the last row in the group  
#    Hr_min cmpny_name Hr_Min_Sec Price
# 1:  09:15          A   09:15:43  7654
# 2:  09:16          A   09:16:59  7854
# 3:  09:17          A   09:17:58  7557
# 4:  09:18          A   09:18:59  7810