使用 R 中的多个条件删除 df 中的行

Question

是否可以通过从 2 个或更多列中引用特定字符串或因子水平来删除数据行？对于小型数据集，这很容易，因为我可以滚动浏览数据框并删除我想要的行，但是对于较大的数据集，如果不不断滚动以查看哪些行符合我的条件，如何实现这一点？

虚假数据：

df1 <- data.frame(year = rep(c(2019, 2020), each = 10),
                  month = rep(c("March", "October"), each = 1), 
                  site = rep(c("1", "2", "3", "4", "5"), each = 2),
                  common_name = rep(c("Tuna", "shark"), each = 1),
                  num = sample(x = 0:2, size  = 20, replace = TRUE))

例如：如何在一行代码中只删除 2019 年 3 月的站点“1”，而不查看它在哪一行？

Answer 1

您可以使用 subset():

df1 <- data.frame(year = rep(c(2019, 2020), each = 10),
                  month = rep(c("March", "October"), each = 1), 
                  site = rep(c("1", "2", "3", "4", "5"), each = 2),
                  common_name = rep(c("Tuna", "shark"), each = 1),
                  num = sample(x = 0:2, size  = 20, replace = TRUE))

subset(df1, !(site == "1" & year == 2019 & month == "March"))
#>    year   month site common_name num
#> 2  2019 October    1       shark   0
#> 3  2019   March    2        Tuna   1
#> 4  2019 October    2       shark   0
#> 5  2019   March    3        Tuna   0
#> 6  2019 October    3       shark   0
#> 7  2019   March    4        Tuna   2
#> 8  2019 October    4       shark   2
#> 9  2019   March    5        Tuna   0
#> 10 2019 October    5       shark   2
#> 11 2020   March    1        Tuna   1
#> 12 2020 October    1       shark   1
#> 13 2020   March    2        Tuna   2
#> 14 2020 October    2       shark   2
#> 15 2020   March    3        Tuna   1
#> 16 2020 October    3       shark   0
#> 17 2020   March    4        Tuna   1
#> 18 2020 October    4       shark   0
#> 19 2020   March    5        Tuna   0
#> 20 2020 October    5       shark   2

^{由 reprex package (v2.0.1)}

创建于 2022-05-31

Answer 2

我们也可以使用 paste

subset(df1, paste(year, month, site) != '2019 March 1')

-输出

   year   month site common_name num
2  2019 October    1       shark   1
3  2019   March    2        Tuna   1
4  2019 October    2       shark   2
5  2019   March    3        Tuna   0
6  2019 October    3       shark   0
7  2019   March    4        Tuna   2
8  2019 October    4       shark   1
9  2019   March    5        Tuna   1
10 2019 October    5       shark   1
11 2020   March    1        Tuna   1
12 2020 October    1       shark   1
13 2020   March    2        Tuna   1
14 2020 October    2       shark   2
15 2020   March    3        Tuna   1
16 2020 October    3       shark   0
17 2020   March    4        Tuna   1
18 2020 October    4       shark   1
19 2020   March    5        Tuna   1
20 2020 October    5       shark   2

Answer 3

使用 R 括号表示法替代 subset 或 dplyr:filter 的一行：

df2 <- df1[!(df1$site=="1" & df1$year==2019 & df1$month=="March"),]

使用 R 中的多个条件删除 df 中的行

Remove rows in df using multiple conditions in R

r

subset