问题描述
如何根据各行上的条件选择组,例如,使包含至少一个(任意)的特定值的所有组保持不变,例如4(或任何其他至少满足 TRUE
的条件).或反过来说:如果组 not 中没有任何行,且条件为true,则应删除整个组.
How to select groups based on a condition on the individual rows, say keep all groups that contain at least one (ANY) of a certain value, e.g. 4, (or any other condition that is TRUE
at least once). Or phrased the other way around: if a group does not have any rows where condition is true, the entire group should be removed.
让我们采用一个非常简单的数据,分为两个组,我想选择具有至少一行且 Value
为4的组(即组 B 此处)
Let's take a very simple data, with two groups, and I want to select the group that has at least one row with a Value
of 4, (i.e. group B here)
library(dplyr)
df <- data.frame(Group = LETTERS[c(1,1,1,2,2,2)], Value=c(1:5, 4))
df
# Group Value
# 1 A 1 # Group A has no values == 4 ~~> remove entire group
# 2 A 2
# 3 B 3
# 4 B 4 # Group B has at least one 4 ~~> keep the whole group
先执行 group_by()
,然后执行 filter
(如)只会选择包含值4的单个行,而不是整个组:
df %>%
group_by(Group) %>%
filter(Value == 4)
# Group Value
# <fctr> <int>
# 1 B 4
推荐答案
事实证明这很容易:您只需要在 filter 中使用
any()
函数调用.确实,看来:
filter(...)
也会在 rowwise()
级别上求值.
df %>%
group_by(Group) %>%
filter(any(Value==4))
Group Value
<fctr> <int>
1 B 3
2 B 4
Interestingly, the same appear with mutate, compare:
df %>%
group_by(Group) %>%
mutate(check1=any(Value==4),
check2=Value==4)
Group Value check1 check2
<fctr> <int> <lgl> <lgl>
1 A 1 FALSE FALSE
2 A 2 FALSE FALSE
3 B 3 TRUE FALSE
4 B 4 TRUE TRUE
这篇关于选择具有至少一个特定值的组的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!