用字符串减去列

Question

我想创建一个第3列，它创建了前两列组件的差值的总和。

x <- data.frame("Start" = c("21,22","14,15","2,4,6,8,10"),
                "End" = c("31,32","19,20","12,14,16,18,20"))

行1列3应为(31-21)+(32-22) = 20。

行2列3应为(19-14)+(20-15) = 10。

第3行第3列应为(12-2)+(14-4)+(16-6)+(18-8)+(20-10)=50。

Answer 1

尝试：

# install.packages("tidyverse") # if needed
library(tidyverse)

final <- x %>% 
  mutate(startList = str_split(Start, ","),
         endList = str_split(End, ",")) %>% 
  unnest(startList, endList) %>% 
  mutate(subtraction = as.numeric(endList) - as.numeric(startList)) %>% 
  group_by(Start, End) %>% 
  mutate(calc = sum(subtraction)) %>% 
  slice(1) %>% 
  ungroup() %>% 
  select(Start, End, calc)

Answer 2

下面将使用tidyverse，来自purr的map，来自stringr的str_split

get_sum = function(z){
  sum(as.numeric(z))
}

x %>% 
  mutate(col3 = unlist(map(str_split(End, ','), get_sum)) - unlist(map(str_split(Start, ','), get_sum)))

       Start            End col3
1      21,22          31,32   20
2      14,15          19,20   10
3 2,4,6,8,10 12,14,16,18,20   50

Answer 3

扫描函数可以读取单个值，就像它们是小csv文件一样，然后可以使用diff和colSums处理结果

apply(x, 1, function(z){ diff( colSums( # the differences of the col sums
          sapply( z,   # sapply will return two column matrices
                function(y)  as.numeric( scan( text=y, sep=",", what="") 
                  )          )          )    )
                        })
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[1] 20 10 50