从特定行/颜色中提取值并添加到另一个中

Question

开始数据：

data = data.frame("Student" = c(1,2,3,4,5),
                  "Class" = c('A','A','B','C','C'),
                  "Score1" = c(7,4,7,2,1),
                  "Score2" = c(2,2,0,10,4),
                  "Score3" = c(8,1,3,2,2))

所需的输出：

data1 = data.frame("Student" = c(1,2,3,4,5),
                   "Class" = c('A','A','B','C','C'),
                   "Score1" = c(0,0,7,2,1),
                   "Score2" = c(0,0,0,10,4),
                   "Score3" = c(17,7,3,2,2))

对于“类”为“ A”的所有行，我想将“ Score1”和“ Score2”添加到“ Score 3”并将“ Score1”和“ Score2”设置为0。

Answer 1

基本的R选项是：

#find rows where class is "A"
inds <- data$Class == "A"
#Add sum of the values in col3
data$Score3[inds] <- rowSums(data[inds, -c(1:2)])
#Turn Score1 and Score2 to 0
data[inds, c("Score1", "Score2")] <- 0

#  Student Class Score1 Score2 Score3
#1       1     A      0      0     17
#2       2     A      0      0      7
#3       3     B      7      0      3
#4       4     C      2     10      2
#5       5     C      1      4      2

使用data.table也可以完成
library(data.table)

setDT(data)
data[inds, Score3 := rowSums(.SD), .SDcols = grep('Score', names(data))]
data[inds, c('Score1', 'Score2') := 0]

Answer 2

您可以如下使用data.table软件包：

library(data.table)

cols <- c("Score1", "Score2", "Score3")
setDT(data)[Class=="A", (cols) := .(0, 0, rowSums(.SD)), .SDcols = cols]

#    Student  Class Score1 Score2 Score3
# 1:       1      A      0      0     17
# 2:       2      A      0      0      7
# 3:       3      B      7      0      3
# 4:       4      C      2     10      2
# 5:       5      C      1      4      2

Answer 3

带有apply和dplyr包的另一个选项：

data %>%
  mutate(Score3 = apply(select(data, starts_with('Score')), 1, sum)) %>%
  mutate(Score1 = 0, Score2 = 0)

Answer 4

另一种选择是使用流行的dplyr和magrittr软件包：

基本上是if-else条件，使用case_when中的dplyr操作完成。

library(dplyr); library(magrittr) #load the packages
data_output <- data %>% mutate(Score1 = (case_when(Class == "A" ~ 0,#if Class is `A`, then Score1 is set to `0` 
                                                   Class != "A" ~ Score1)),                                              
                               Score2 = (case_when(Class == "A" ~ 0, 
                                                   Class != "A" ~ Score2)), 
                               Score3 = (case_when(Class == "A" ~ Score1 + Score2, 
                                                   Class != "A" ~ Score3)));
data_output
Student Class Score1 Score2 Score3
1       1     A      0      0      0
2       2     A      0      0      0
3       3     B      7      0      3
4       4     C      2     10      2
5       5     C      1      4      2