通过增加频率重新排序因子

问题描述

如何按频率对因子值列重新排序 - 按升序排列?

How do I reorder factor-valued columns by frequency - in increasing order?

虽然 forcats 包提供了一种基于频率重新排序因子的明确方法(fct_infreq())，它以降频顺序进行.我需要因子频率/计数的相反顺序.

While the forcats package provides an explicit way to reorder a factor based on its frequency (fct_infreq()), it does so in decreasing frequency order. I need the reverse order of the factor frequency/counts.

例如

library(forcats)
set.seed(555)
df <- data.frame(x=factor(sample(as.character(1:10), 100, replace=TRUE)))
table(df$x)

1 10   2  3  4  5  6  7  8  9 
9 10  12 14 10 10  5 12  8 10 

levels(fct_infreq(df$x))

[1] "3"  "2"  "7"  "10" "4"  "5"  "9"  "1"  "8"  "6" 

是否有一种简单的方法可以颠倒顺序，使最不频繁的因子(6")在前，最频繁的(3")在后?

Is there a simple way to flip the ordering so that the least frequent factor ("6") is first and the most frequent ("3") last?

推荐答案

这可以通过使用 fct_rev 如下:

This can be done simply by using fct_rev as follows:

levels(fct_rev(fct_infreq(df$x)))

[1] "6"  "8"  "1"  "9"  "5"  "4"  "10" "7"  "2"  "3" 

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