在R中更改基于另一个数据帧的单元格

在这种情况下，如果df1==1中的单元格新值是当前df2单元格，我想用另一个dataframe的值创建一个新列

df1 <- c("1","2","3","4","5")
df2 <- c("a","b","c","d","e")

df <- cbind(df1,df2)
df
     df1 df2
[1,] "1" "a"
[2,] "2" "b"
[3,] "3" "c"
[4,] "4" "d"
[5,] "5" "e"

---

事先非常感谢

您可以使用

ifelse

：

transform(df, my_col = ifelse(df1 == 1, df2, df1))

#  df1 df2 my_col
#1   1   a      a
#2   2   b      2
#3   3   c      3
#4   4   d      4
#5   5   e      5

library(dplyr)
df %>%mutate(my_col = ifelse(df1 == 1, df2, df1))

dplyr中的等效项：

transform(df, my_col = ifelse(df1 == 1, df2, df1))

#  df1 df2 my_col
#1   1   a      a
#2   2   b      2
#3   3   c      3
#4   4   d      4
#5   5   e      5

library(dplyr)
df %>%mutate(my_col = ifelse(df1 == 1, df2, df1))

---

或者先复制

df1

值，然后替换

df$my_col <- df$df1
df$my_col[df$df1 == 1] <- df$df2[df$df1 == 1]

---

df$my\u col您可以使用
ifelse
：

transform(df, my_col = ifelse(df1 == 1, df2, df1))

#  df1 df2 my_col
#1   1   a      a
#2   2   b      2
#3   3   c      3
#4   4   d      4
#5   5   e      5

library(dplyr)
df %>%mutate(my_col = ifelse(df1 == 1, df2, df1))

dplyr中的等效项

：

transform(df, my_col = ifelse(df1 == 1, df2, df1))

#  df1 df2 my_col
#1   1   a      a
#2   2   b      2
#3   3   c      3
#4   4   d      4
#5   5   e      5

library(dplyr)
df %>%mutate(my_col = ifelse(df1 == 1, df2, df1))

---

或者先复制

df1

值，然后替换

df$my_col <- df$df1
df$my_col[df$df1 == 1] <- df$df2[df$df1 == 1]

---

df$my_col使用
数据。表将就地分配

library(data.table)
setDT(df)[, my_col := df1][df1 == 1, my_col := df2]
df
#   df1 df2 my_col
#1:   1   a      a
#2:   2   b      2
#3:   3   c      3
#4:   4   d      4
#5:   5   e      5


或使用
fifelse

setDT(df)[, my_col := fifelse(df1 == 1, df2, df1)]

或使用
fcase

setDT(df)[, my_col := fcase(df1 == 1, df2, default = df1)]

数据
df使用
数据。表将就地分配

library(data.table)
setDT(df)[, my_col := df1][df1 == 1, my_col := df2]
df
#   df1 df2 my_col
#1:   1   a      a
#2:   2   b      2
#3:   3   c      3
#4:   4   d      4
#5:   5   e      5


或使用
fifelse

setDT(df)[, my_col := fifelse(df1 == 1, df2, df1)]

或使用
fcase

setDT(df)[, my_col := fcase(df1 == 1, df2, default = df1)]

数据
df