如何根据另一个列条件删除重复的行？

Question

如何根据第二列中的max选择重复行(仅基于第一列):

data<-data.frame(a=c(1,3,3,3),b=c(1,4,6,3),d=c(1,5,7,1))

a b d
1 1 1
3 4 5
3 6 7
3 3 1


a b d
1 1 1
3 6 7

在第二列中,6最大值在4,6,3之间

Answer 1

您可以使用"dplyr"尝试以下内容:

library(dplyr)

data %>%                  ## Your data
  group_by(a) %>%         ##   grouped by "a"
  filter(b == max(b))     ##   filtered to only include the rows where b == max(b)
# Source: local data frame [2 x 3]
# Groups: a
# 
#   a b d
# 1 1 1 1
# 2 3 6 7

但请注意,如果还有更多匹配的行,b == max(b)也会返回.因此,替代方案可能是:

data %>%                  ## Your data
  group_by(a) %>%         ##   grouped by "a"
  arrange(desc(b)) %>%    ##   sorted by descending values of "b"
  slice(1)                ##   with just the first row extracted