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r - 如何比较不同顺序的因子水平？

问题描述

df <- data.frame(
    cola = c('a','b','c','d','e','e','1',NA,'c','d'),
    colb = c("A",NA,"C","D",'a','b','c','d','c','d'),stringsAsFactors = FALSE)
#equal 2 dataframe
df2<-df

df['cola'] <- lapply(df['cola'], function(x) droplevels(factor(x,levels=c('a','b','c','d','e','f','1'),ordered = FALSE)))

df2['cola'] <- lapply(df2['cola'], function(x) factor(x,ordered = FALSE))

#should be eqaul
dplyr::all_equal(df,df2)

#check levels
levels(df$cola)
levels(df2$cola)

上述脚本的输出是： 

> dplyr::all_equal(df,df2)
[1] "Factor levels not equal for column `cola`"

> levels(df$cola)
[1] "a" "b" "c" "d" "e" "1"

> levels(df2$cola)
[1] "1" "a" "b" "c" "d" "e"

至于ordered = FALSE，"a" "b" "c" "d" "e" "1" 应该等于"1" "a" "b" "c" "d" "e"
为什么all_equal告诉我Factor levels not equal？

如何比较这两个因素水平是否相等？

标签： r

解决方案

如果您使用原始all.equal.

all.equal(df, df2)
# [1] "Component “cola”: Attributes: < Component “levels”: 6 string mismatches >"

你们的水平不匹配。这与比较 data.frame 或两个字符串向量的列很简洁：

all.equal(letters[c(3, 1, 2)], letters[c(2, 3, 1)])
# [1] "3 string mismatches"

你可以sort改用。

sort(levels(df$cola)) == sort(levels(df2$cola))
# [1] TRUE TRUE TRUE TRUE TRUE TRUE

要检查所有，请使用all.

all(sort(levels(df$cola)) == sort(levels(df2$cola)))
# [1] TRUE

你可以把它包装成一个函数。

checkEqualLevels <- function(l, x, y) {
  if (all(sort(levels(x[[l]])) == sort(levels(y[[l]]))))
    cat(paste0("Factor levels are equal for column ", "'", l, "'"))
  else
    cat(paste0("Factor levels not equal for column ", "'", l, "'"))
}
checkEqualLevels("cola", df, df2)
# Factor levels are equal for column 'cola'

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