R for循环与字符列表 [英] R for loop with characters list

问题描述

我有一个df，例如:

name <- rep(c("a","b","c"),5)
QV.low <- runif(15, 2, 5)
QV.med <- runif(15, 5.0, 7.5)
QV.high <- runif(15, 7.5, 10)
df <-  as.data.frame(cbind(name, QV.low, QV.med,QV.high))

和名称列表:

name.list <- c("a","b")

我想做一个手术，例如:

I want to do an operation, eg:

df %>% 
    subset(name %in% name.list) %>%
    summarise(.,sum = sum(QV.low))

但是我想通过循环为每个QV.变量.

but I want to for each QV. variable via a loop.

我尝试过:

QV.list <- c("QV.low", "QV.med", "QV.high")
for(qv in 1:length(QV.list)){
    QV <- noquote(QV.list[qv])
    print(QV)
    df %>% 
        subset(name %in% name.list) %>%
        summarise(.,sum = sum(QV))
}

但是它不起作用.

如何从QV.list中提取"字符值，以便以后将其用作df变量?

How can I "extract" the character value from the QV.list in order to use it as df variable later?

推荐答案

namecol中至少需要3个不同的名称，否则namecol %in% name.list1是没有用的.如果没有过滤器也没有管道，则无需循环.一个简单的colSums(df[,-1])即可完成工作.

You need to have at least 3 different names in namecol otherwise namecol %in% name.list1 is useless. If there's no filter and no pipe, there's no need for a loop. A simple colSums(df[,-1]) will do the job.

library(tidyverse)

QV.low <- runif(10, 2, 5)
QV.med <- runif(10, 5.0, 7.5)
QV.high <- runif(10, 7.5, 10)
namecol <- sample(c("a","b", "c"), 10, replace = T)
df <-  data.frame(namecol, QV.low, QV.med,QV.high)
df
name.list1  <- c("a","b") # select some names

QV.list <- c("QV.low", "QV.med", "QV.high")

for(i in QV.list){
  QV <- noquote(i)
  print(QV)
  qv <- sym(i)
  print(df %>% 
    filter(namecol %in% name.list1) %>%
    summarise(sum = sum(!!qv)))
}

会给你

[1] QV.low
     sum
1 29.093
[1] QV.med
       sum
1 61.07034
[1] QV.high
       sum
1 86.02611

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