如何在列行中添加新字符串

Question

需要使用新计算添加新字符串

Strength	Value
2 ml	10
5 ml	05
2 ml	30
5 ml	40
2 ml	10
5 ml	25
2 ml	30
5 ml	20
2 ml	15
5 ml	10

现在我需要在 Strength 列中添加 New String Total (2 ml + 5 ml)

所以 table 将如下所示

Strength	Value
2 ml	10
5 ml	05
Total	15
2 ml	30
5 ml	40
Total	70
2 ml	10
5 ml	25
Total	35
2 ml	30
5 ml	20
Total	50
2 ml	15
5 ml	10
Total	25

Answer 1

使用by

do.call(
  rbind,
  by(
    df,
    rep(1:(nrow(df)/2),each=2),
    function(x){
      rbind(
        x,
        data.frame(
          "Strength"="Total",
          "Value"=sum(x$Value)
        )
      )
    }
  )
)

     Strength Value
1.1      2 ml    10
1.2      5 ml     5
1.3     Total    15
2.3      2 ml    30
2.4      5 ml    40
2.1     Total    70
3.5      2 ml    10
3.6      5 ml    25
3.1     Total    35
4.7      2 ml    30
4.8      5 ml    20
4.1     Total    50
5.9      2 ml    15
5.10     5 ml    10
5.1     Total    25

Answer 2

您可以尝试使用 dplyr，让您的数据 df

library(dplyr)

df %>%
  mutate(n = floor((1:n()-1)/2)) %>%
  group_by(n) %>%
  group_modify(., function(x, y) bind_rows(x, summarise(x, Strength = "Total",
                                                      Value = sum(Value)))) %>% 
  ungroup %>%
  select(-n)

   Strength Value
   <chr>    <int>
 1 2 ml        10
 2 5 ml         5
 3 Total       15
 4 2 ml        30
 5 5 ml        40
 6 Total       70
 7 2 ml        10
 8 5 ml        25
 9 Total       35
10 2 ml        30
11 5 ml        20
12 Total       50
13 2 ml        15
14 5 ml        10
15 Total       25

Answer 3

通过基础 R 的标准 split/apply/combine 方法，

i1 <- split(df1, f = cumsum(seq(nrow(df1)) %% 2))
do.call(rbind, 
        lapply(i1, function(i){i[nrow(i) + 1,] <- data.frame(Strength = 'Total', 
                                                             Value = sum(i$Value));i}))

     Strength Value
1.1       2ml    10
1.2       5ml     5
1.3     Total    15
2.3       2ml    30
2.4       5ml    40
2.1     Total    70
3.5       2ml    10
3.6       5ml    25
3.1     Total    35
4.7       2ml    30
4.8       5ml    20
4.1     Total    50
5.9       2ml    15
5.10      5ml    10
5.1     Total    25

Answer 4

df %>%
  # create a group identifier:
  mutate(grp = rep(1:(nrow(.)/2), each=2)) %>%
  # for each group:
  group_by(grp) %>%
  # calculate the sum of `Value`:
  summarise(Value = sum(Value)) %>%
  # create a column `Strength` with value `Total`:
  mutate(Strength = "Total") %>%
  # bind result back to df while creating, again, group identifier:
  bind_rows(.,df %>% mutate(grp = rep(1:(nrow(.)/2),each=2))) %>%
  # order by group:
  arrange(grp) %>%
  # remove grouping varible:
  select(-grp)
# A tibble: 6 × 2
  Value Strength
  <dbl> <chr>   
1    15 Total   
2    10 2 ml    
3     5 5 ml    
4    70 Total   
5    30 2 ml    
6    40 5 ml

如何在列行中添加新字符串

How to add new string in column row

r