通过聚合动态列名匹配进行分组 [英] Group by aggregate dynamic column name matching
问题描述
可以使用dplyr在列名上使用正则表达式匹配 group_by
library(dplyr)#dplyr_0.5.0; R版本3.3.2(2016-10-31)
#虚拟数据
set.seed(1)
df1< - sample_n(iris,20)%> %
mutate(Sepal.Length = round(Sepal.Length),
Sepal.Width = round(Sepal.Width))
由静态组合(看起来/工作正常,想像如果我们有10-20列):
df1%>%
group_by(Sepal.Length,Sepal.Width)%>%
summaryize(mySum = sum(Petal.Length) )
由动态分组 - 丑陋版本:
df1%>%
group_by _(。dots = colnames(df1)[grepl(^ Sepal,colnames(df1) )])%>%
总结(mySum = sum(Petal.Length))
理想情况下,这样(不起作用,因为 starts_with
返回索引):
code> df1%>%
group_by(starts_with(Sepal))%>%
summaryize(mySum = sum(Petal.Length))
eval(expr,envir, code>
预期输出:
#来源:本地数据框[6 x 3]
#组:Sepal.Length [?]
#
#Sepal.Length Sepal.Width mySum
#< dbl> < DBL> < DBL>
#1 4 3 1.4
#2 5 3 10.9
#3 6 2 4.0
#4 6 3 43.7
#5 7 3 15.7
# 6 8 4 6.4
注意: / strong>听起来很像一个重复的帖子,请联系相关的帖子(如果有的话)。
此功能将在未来版本,参考 GitHub问题#2619 :
解决方案是使用 group_by_at
function:
df1%>%
group_by_at(vars(starts_with(Sepal)))%>%
总结(mySum = sum(Petal.Length))
Is it possible to group_by
using regex match on column names using dplyr?
library(dplyr) # dplyr_0.5.0; R version 3.3.2 (2016-10-31)
# dummy data
set.seed(1)
df1 <- sample_n(iris, 20) %>%
mutate(Sepal.Length = round(Sepal.Length),
Sepal.Width = round(Sepal.Width))
Group by static version (looks/works fine, imagine if we have 10-20 columns):
df1 %>%
group_by(Sepal.Length, Sepal.Width) %>%
summarise(mySum = sum(Petal.Length))
Group by dynamic - "ugly" version:
df1 %>%
group_by_(.dots = colnames(df1)[ grepl("^Sepal", colnames(df1))]) %>%
summarise(mySum = sum(Petal.Length))
Ideally, something like this (doesn't work, as starts_with
returns indices):
df1 %>%
group_by(starts_with("Sepal")) %>%
summarise(mySum = sum(Petal.Length))
Error in eval(expr, envir, enclos) : wrong result size (0), expected 20 or 1
Expected output:
# Source: local data frame [6 x 3]
# Groups: Sepal.Length [?]
#
# Sepal.Length Sepal.Width mySum
# <dbl> <dbl> <dbl>
# 1 4 3 1.4
# 2 5 3 10.9
# 3 6 2 4.0
# 4 6 3 43.7
# 5 7 3 15.7
# 6 8 4 6.4
Note: sounds very much like a duplicated post, kindly link the relevant posts if any.
This feature will be implemented in future release, reference GitHub issue #2619:
Solution would be to use group_by_at
function:
df1 %>%
group_by_at(vars(starts_with("Sepal"))) %>%
summarise(mySum = sum(Petal.Length))
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