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通过比较R[duplicate]中一列中的值来选择行

dplyr group-by filter r

Ali Hadjihoseini · 技术社区 · 7 年前

我有一个数据框,看起来像:

n4= 
    sector turb    dist
    1  sector1  T02  828.66
    2  sector1  T04 1114.58
    3  sector1  T05 1012.22
    4  sector2  T03  992.64
    5  sector2  T05 1012.22
    6  sector2  T06 1158.38
    7  sector3  T03  992.64
    8 sector12  T02  828.66
    9 sector12  T04 1114.58

我希望保留具有唯一扇区名称的行,并且度量值是在dist列中保留具有最小值的行:

 sector turb   dist
1  sector1  T02 828.66
4  sector2  T03 992.64
7  sector3  T03 992.64
8 sector12  T02 828.66

我知道我必须根据行业对他们进行分类:

result = n4 %>%
dplyr::group_by(sector)

但是使用select或filter命令并没有像我尝试的那样起作用:

result = n4 %>%
    dplyr::group_by(sector)%>%
    dplyr::select(which.min(dist))

你知道我怎么做吗?

2 回复 | 直到 7 年前

Jilber Urbina 7 年前

你可以用 filter 而不是 select 作为替代品 slice

> n4 %>%
    dplyr::group_by(sector)%>%
    dplyr::filter(dist==min(dist))
# A tibble: 4 x 3
# Groups:   sector [4]
  sector   turb   dist
  <fct>    <fct> <dbl>
1 sector1  T02    829.
2 sector2  T03    993.
3 sector3  T03    993.
4 sector12 T02    829.

如果你喜欢使用R基,试试 aggregate

> aggregate(.~sector, data=n4, min)
    sector turb   dist
1  sector1    1 828.66
2 sector12    1 828.66
3  sector2    2 992.64
4  sector3    2 992.64

check this answer

akrun 7 年前

我们需要 slice 而不是 select 将行子集化。这个函数用于选择数据集的列。如果“扇区”的顺序应与输入数据中“扇区”的出现顺序相同,则将列更改为a factor 具有 levels 在输入数据顺序中指定

n4 %>%       
   dplyr::group_by(sector = factor(sector, levels = unique(sector)))%>%
   dplyr::slice(which.min(dist))
# A tibble: 4 x 3
# Groups:   sector [4]
#  sector   turb   dist
#  <fct>    <chr> <dbl>
#1 sector1  T02    829.
#2 sector2  T03    993.
#3 sector3  T03    993.
#4 sector12 T02    829.

或使用 base R

n4[with(n4, ave(dist, sector, FUN = min) == dist),]
#     sector turb   dist
#1  sector1  T02 828.66
#4  sector2  T03 992.64
#7  sector3  T03 992.64
#8 sector12  T02 828.66

数据

n4 <- structure(list(sector = c("sector1", "sector1", "sector1", "sector2", 
"sector2", "sector2", "sector3", "sector12", "sector12"), turb = c("T02", 
"T04", "T05", "T03", "T05", "T06", "T03", "T02", "T04"), dist = c(828.66, 
 1114.58, 1012.22, 992.64, 1012.22, 1158.38, 992.64, 828.66, 1114.58
)), class = "data.frame", row.names = c("1", "2", "3", "4", "5", 
"6", "7", "8", "9"))

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