R语言使用duplicated函数去除重复项

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我是靠谱客的博主义气金鱼，最近开发中收集的这篇文章主要介绍R语言使用duplicated函数去除重复项，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

首先复习一下数据结构：vevtor的基本单元是元素，数据狂的基本元素是？对，行。

然后再看一下duplicated()的description：

duplicated() determines which elements of a vector or data frame are duplicates of elements with smaller subscripts, and returns a logical vector indicating which elements (rows) are duplicates.

就是说呢duplicated返回重复元素or重复行的逻辑logical vector，而且是第二个(True)

代码演示“

x1 = c(1,2,3,4,5,1,3,5)

test <- data.frame(

  x1 = c(1,2,3,4,5,1,3,5),

  x2 = c("a","b","c","d","e","a","b","e"),

  x3 = c("k","b","c","d","e","a","c","e")

)

duplicated(x1)

[1] FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE  TRUE

test[!duplicated(test),]

  x1 x2 x3
1  1  a  k
2  2  b  b
3  3  c  c
4  4  d  d
5  5  e  e
6  1  a  a
7  3  b  c

duplicated有两个参数还算有用

incomparables

a vector of values that cannot be compared. FALSE is a special value, meaning that all values can be compared, and may be the only value accepted for methods other than the default. It will be coerced internally to the same type as x.

给定一个数字向量，里面的数字都不需要比较有无重复。起到设置例外的作用。

fromLast

logical indicating if duplication should be considered from the reverse side, i.e., the last (or rightmost) of identical elements would correspond to duplicated = FALSE.

如果TRUE那么返回TURE的值就会变成“不重复的”为真（TURE）。

例如

> x1 <- c(1,2,3,4,5,1,3,5)

> duplicated(x1,fromLast = T)

[1]  TRUE FALSE  TRUE FALSE  TRUE FALSE FALSE FALSE

> duplicated(x1,incomparables = c(3))

[1] FALSE FALSE FALSE FALSE FALSE  TRUE FALSE  TRUE

> duplicated(x1,incomparables = c(5,3))

[1] FALSE FALSE FALSE FALSE FALSE  TRUE FALSE FALSE