如何使用R执行按长度排序的因子分解

Question

例如，我有一个向量：

df <- c(NA, "Travellers' Choice, Certificate of Excellence 2020, Certificate of Excellence 2017", "Certificate of Excellence 2017","Certificate of Excellence 2018, Certificate of Excellence 2017, Certificate of Excellence 2016")

我想做这样的事情：

df.ordered <- as.numeric(factor(df, levels=length(df), ordered=TRUE))

要将其作为输出：

[1] NA 10 4 12
Levels: 4 < 10 < 12

Answer 1

您只需要使级别成为向量中的唯一值：

as.numeric(factor(df, levels=sort(unique(df)), ordered=TRUE))

[1] 3 2 3 1