是否有将字符串迭代器转换为 R 代码的方法？

编程问答 2022-05-14

问题描述

我正在尝试计算数据框中所有列的平均值（平均值）。我已经创建了这个代码片段

#Average overallDataset by label
overallDatasetLabels <- c("label","index","nr_pix","rows_with_2","cols_with_2","rows_with_3p","cols_with_3p","height","width","left2tile","right2tile","verticalness","top2tile","bottom2tile","horizontalness","nodiagnols")
library(dplyr)
avgoverallDataset <- summarise(group_by(overallDataset,label),nr_pix_avg=mean(nr_pix))
for (val in overallDatasetLabels){
  if (val %in% c("label","nr_pix")){
    next
  }
  avgoverallDataset<-cbind(avgoverallDataset,summarise(group_by(overallDataset,val=mean(val)))
}

当我运行此代码时，我收到此错误/警告：

50: In mean.default(val) : argument is not numeric or logical: returning NA

生成的数据框如下所示：

enter image description here

这样做的原因是 val 变量被视为字符串，但我需要将其视为“代码”，例如

avgoverallDataset<- cbind(avgoverallDataset,avgrows_with_2=mean(rows_with_2)))

应该是有效的。

如何将“字符串”转换为“代码中”的值？

注意：可以使用以下方法删除多个标签列：How to remove duplicated column names in R?

解决方法

尝试使用 across，这样您就不必为循环中的多列计算 mean。

cols <- setdiff(overallDatasetLabels,c("label","index","nr_pix"))

avgOverallDataset <- overallDataset %>%
                      group_by(label) %>%
                      summarise(across(all_of(cols),mean,na.rm = TRUE))
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