如何编写程序对重复观测值按ID取A、B变量最大值填充？

Base R Approach #

Use the ave() function to calculate the maximum value of A and B for each ID, then overwrite the original columns with these group-specific maxima.

# Update column A with ID-wise max
j$A <- ave(j$A, j$ID, FUN = max)
# Update column B with ID-wise max
j$B <- ave(j$B, j$ID, FUN = max)

# Check the result
j

Result: #

ID  A  B
1 22 10  8
2 22 10  8
3 23 60 10
4 23 60 10
5 23 60 10
6 23 60 10

dplyr Approach #

For tidy data manipulation, use the dplyr package to group by ID and mutate columns to their group maxima:

library(dplyr)

j <- j %>%
  group_by(ID) %>%
  mutate(
    A = max(A),
    B = max(B)
  ) %>%
  ungroup()

# Check the result
j

Result: #

# A tibble: 6 × 3
     ID     A     B
  <int> <int> <int>
1    22    10     8
2    22    10     8
3    23    60    10
4    23    60    10
5    23    60    10
6    23    60    10

内容的提问来源于stack exchange，提问作者Zebu