如何確定比下一個最大值高2倍的最大值

Question

如何確定每個行的最大值（例如：b1和a4的20），它比下一個最大值（b1的5倍）高2倍a3）同一排？

樣品輸入

name a1 a2 a3 a4 
b1 1 1 5 20 
b2 10 9 20 9 
b3 1 1 1 1 

樣本輸出

b1 a4 20 
b2 a3 20 

Answer 1

隨着：

library(dplyr) 
library(tidyr) 
d %>% 
    gather(k, v, -name) %>% 
    arrange(-v, name) %>% 
    group_by(name) %>% 
    mutate(logi = v/lead(v, default = min(v)) >= 2) %>% 
    filter(v == first(v) & logi) %>% 
    select(-logi) 

結果是：

個

# A tibble: 2 x 3 
# Groups: name [2] 
    name  k  v 
    <fctr> <chr> <int> 
1  b1 a4 20 
2  b2 a3 20 

數據使用：

d <- structure(list(name = structure(1:3, .Label = c("b1", "b2", "b3"), class = "factor"), 
        a1 = c(1L, 10L, 1L), 
        a2 = c(1L, 9L, 1L), 
        a3 = c(5L, 20L, 1L), 
        a4 = c(20L, 9L, 1L)), 
       .Names = c("name", "a1", "a2", "a3", "a4"), class = "data.frame", row.names = c(NA, -3L))