根据 r 中另一个数据框中的特征获取每次观察的平均值

Question

我有两个数据框

df1
#    var1 var2
# 1 X01    Red
# 2 X02    Green
# 3 X03    Red
# 4 X04    Yellow
# 5 X05    Red
# 6 X06    Green

df2
#   X01    X02    X03   ...
# 1 1      0.1    2.1
# 2 2      0.2    2.2
# 3 3      0.3    2.3
# 4 4      0.4    2.4
# 5 5      0.5    2.5
# 6 6      0.6    2.6

是否有可能在 df2 中得到一个名为 'Red' 的新变量作为每次观察的平均值？

df2
#   X01    X02    X03   Red
# 1 1      0.1    2.1   mean obs1
# 2 2      0.2    2.2   mean obs2
# 3 3      0.3    2.3   mean obs3
# 4 4      0.4    2.4   mean obs4
# 5 5      0.5    2.5   mean obs5
# 6 6      0.6    2.6   mean obs6

Answer 1

我们可以使用 base R split 根据第一个数据 'var1' 的 matching 值拆分第二个数据集，Filter list 元素仅在超过 1 列时应用 rowMeans，然后遍历 list，应用 rowMeans 并将它们分配为 [=33 中的新列=]

lst1 <- split.default(df2, df1$var2[match(names(df2), df1$var1)])
lst2 <- Filter(function(x) ncol(x) > 1, lst1)
tmp <-  lapply(lst2,
      rowMeans, na.rm = TRUE)
df2[names(tmp)] <- tmp

-输出

> df2
  X01 X02 X03  Red
1   1 0.1 2.1 1.55
2   2 0.2 2.2 2.10
3   3 0.3 2.3 2.65
4   4 0.4 2.4 3.20
5   5 0.5 2.5 3.75
6   6 0.6 2.6 4.30

或在 for 循环中

for(nm in unique(df1$var2)) {
   v1 <- intersect(df1$var1[df1$var2 == nm], names(df2))
   if(length(v1) > 1) df2[[nm]] <- rowMeans(df2[v1], na.rm = TRUE)
}

数据

df1 <- structure(list(var1 = c("X01", "X02", "X03", "X04", "X05", "X06"
), var2 = c("Red", "Green", "Red", "Yellow", "Red", "Green")), 
class = "data.frame", row.names = c("1", 
"2", "3", "4", "5", "6"))

df2 <- structure(list(X01 = 1:6, X02 = c(0.1, 0.2, 0.3, 0.4, 0.5, 0.6
), X03 = c(2.1, 2.2, 2.3, 2.4, 2.5, 2.6)), 
class = "data.frame", row.names = c("1", 
"2", "3", "4", "5", "6"))

Answer 2

library(tidyverse)

df2 %>%
  rowid_to_column() %>%
  pivot_longer(-rowid, names_to = 'var1') %>%
  left_join(df1) %>%
  pivot_wider(rowid, names_from = var2, values_fn = mean) %>%
  cbind(df2,.)

  X01 X02 X03 rowid  Red Green
1   1 0.1 2.1     1 1.55   0.1
2   2 0.2 2.2     2 2.10   0.2
3   3 0.3 2.3     3 2.65   0.3
4   4 0.4 2.4     4 3.20   0.4
5   5 0.5 2.5     5 3.75   0.5
6   6 0.6 2.6     6 4.30   0.6

根据 r 中另一个数据框中的特征获取每次观察的平均值

Get mean per observation based in characteristics in another dataframe in r

r

dataframe

crosstab

数据