根据向量中的值过滤数据框行 [英] Filter data frame rows based on values in vector

问题描述

当要删除的值存储在向量中时，从数据框中过滤行的最佳方法是什么?就我而言，我有一列包含日期并想删除多个日期.

What is the best way to filter rows from data frame when the values to be deleted are stored in a vector? In my case I have a column with dates and want to remove several dates.

我知道如何删除对应于 one 天的行，使用 !=，例如:

I know how to delete rows corresponding to one day, using !=, e.g.:

m[m$date != "01/31/11", ]

要删除向量中指定的多个日期，我尝试了:

To remove several dates, specified in a vector, I tried:

m[m$date != c("01/31/11", "01/30/11"), ]

但是，这会生成一条警告消息:

However, this generates a warning message:

Warning message:
In `!=.default`(m$date, c("01/31/11", "01/30/11")) :
longer object length is not a multiple of shorter object length
Calls: [ ... [.data.frame -> Ops.dates -> NextMethod -> Ops.times -> NextMethod

基于多个值应用过滤器的正确方法是什么?

What is the correct way to apply a filter based on multiple values?

推荐答案

nzcoops 非常赞同他的建议.不久前我在 R Chat 中提出了这个问题，Paul Teetor 建议定义一个新函数:

nzcoops is spot on with his suggestion. I posed this question in the R Chat a while back and Paul Teetor suggested defining a new function:

`%notin%` <- function(x,y) !(x %in% y) 

然后可以如下使用:

foo <- letters[1:6]

> foo[foo %notin% c("a", "c", "e")]
[1] "b" "d" "f"

不用说，这个小宝石现在在我的 R 个人资料中 并且经常使用.

Needless to say, this little gem is now in my R profile and gets used quite often.

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