如何从最丰富物种到最不丰富物种排列物种列表数据集

Question

我有一个如下所示的数据集。R中是否有一行代码来排列从最丰富的物种(在列中发生的最多)到最少的物种？谢谢!

df <- tibble::tribble(
  ~name,
  "Species A",
  "Species A",
  "Species B",
  "Species C",
  "Species A",
  "Species C",
  "Species B",
  "Species A"
)

Answer 1

您可以尝试使用table，对此进行排序，使用match对names和order进行排序。

df[order(match(df$name, names(sort(table(df$name), decreasing=TRUE)))),]
## A tibble: 8 × 1
#  name     
#  <chr>    
#1 Species A
#2 Species A
#3 Species A
#4 Species A
#5 Species B
#6 Species B
#7 Species C
#8 Species C

或者使用split

. <- split(seq_len(nrow(df)), df$name)
df[unlist(.[order(lengths(.), decreasing=TRUE)], FALSE, FALSE),]
## A tibble: 8 × 1
#  name     
#  <chr>    
#1 Species A
#2 Species A
#3 Species A
#4 Species A
#5 Species B
#6 Species B
#7 Species C
#8 Species C

或者，如果只对向量进行排序：

. <- sort(table(df$name), decreasing=TRUE)
rep(names(.), .)
#[1] "Species A" "Species A" "Species A" "Species A" "Species B" "Species B"
#[7] "Species C" "Species C"

Answer 2

您还可以按事件发生的次数对该因素进行reorder，然后sort该因素：

data$species <- reorder(data$species, data$species, FUN = length) |>
  sort(decreasing = T)

输出

data

    species  
1 Species A
2 Species A
3 Species A
4 Species A
5 Species C
6 Species C
7 Species B
8 Species B

Answer 3

data.table解决方案

library(data.table)

data <- setDT(data)[, n := .N, species][order(-n, species)][, n := NULL]

输出

data

#      species
# 1: Species A
# 2: Species A
# 3: Species A
# 4: Species A
# 5: Species B
# 6: Species B
# 7: Species C
# 8: Species C

数据

data <- tibble(
  species = c(
  "Species A",
  "Species A",
  "Species B",
  "Species C",
  "Species A",
  "Species C",
  "Species B",
  "Species A")
)