如何在R中按鱼类物种条件合并多行并修改Method字段

To solve this problem, we need to aggregate rows by Species, combining entries where a species was caught using both methods while merging the values in the numeric columns. Here's how to do it with tidyverse:

Step-by-Step Code #

library(tidyverse)

fish_catch_processed <- fish_catch %>%
  summarize(
    # Determine the combined fishing method
    Method = case_when(
      # Check if both methods exist in the species group
      all(c("Bottom fishing", "Trolling") %in% Method) ~ "Both",
      # Retain the single method if only one is present
      TRUE ~ as.character(Method[1])
    ),
    # Merge Bait values: sum non-NA entries, keep NA if all are missing
    Bait = ifelse(all(is.na(Bait)), NA_integer_, sum(Bait, na.rm = TRUE)),
    # Merge Released values using the same logic
    Released = ifelse(all(is.na(Released)), NA_integer_, sum(Released, na.rm = TRUE)),
    # Merge Kept values using the same logic
    Kept = ifelse(all(is.na(Kept)), NA_integer_, sum(Kept, na.rm = TRUE)),
    # Group by Species (use .by for dplyr 1.1.0+; replace with group_by(Species) first if using an older version)
    .by = Species
  )

Explanation #

• Method Column: We use case_when to check if both fishing methods are present in the species group. If yes, we set Method to "Both"; otherwise, we keep the single method used for that species.
• Numeric Columns: For Bait, Released, and Kept, we sum non-NA values (using sum(na.rm = TRUE)). If all values in a column are NA, we retain NA instead of converting it to 0, which preserves the original missing data context.

Sample Output #

Running this code on your sample data will produce:

# A tibble: 9 × 5
  Species                  Method           Bait Released  Kept
  <chr>                    <chr>           <int>    <int> <int>
1 Aethaloperca rogaa       Bottom fishing    NA       NA     2
2 Aprion virescens         Bottom fishing    NA       NA     1
3 Balistidae spp.          Bottom fishing    NA       NA     1
4 Caranx ignobilis         Both              NA        1     1
5 Epinephelus fasciatus    Bottom fishing    NA        3    NA
6 Epinephelus multinotatus Bottom fishing    NA       NA     5
7 Other species            Bottom fishing    NA        1    NA
8 Thunnus albacares        Trolling          NA       NA     1
9 Variola louti            Bottom fishing    NA       NA     1

Notice that Caranx ignobilis now has Method = "Both" with merged Released and Kept values, which matches your desired outcome.

内容的提问来源于stack exchange，提问作者Tuna-92