Question

寻找更好的方法：如何让R在元素方面检查多列灵活子集的值（在这里说entrySet和Var2）并写入检查结果到一个新的逻辑列？

在这里使用行式Var3是否有更短，更优雅的方式？

apply()

我也可以用明确的方式做到这一点，但这不是灵活的：

df <- read.csv(
  text = '"Var1","Var2","Var3"
  "","",""
  "","","a"
  "","a",""
  "a","a","a"
  "a","","a"
  "","a",""
  "","",""
  "","","a"
  "","a",""
  "","","a"'
)

criticalColumns <- c("Var2", "Var3")

df$criticalColumnsAreEmpty <-
  apply(df[, criticalColumns], 1, function(curRow) {
    return(all(curRow == ""))
  })

期望的输出：

df$criticalColumnsAreEmpty <- df$Var2 == "" & df$Var3 == ""

Answer 1

我们可以在逻辑矩阵上使用rowSums

df$criticalColumnsAreEmpty <- !rowSums(df[criticalColumns]!="")
df$criticalColumnsAreEmpty
#[1]  TRUE FALSE FALSE FALSE FALSE FALSE  TRUE FALSE FALSE FALSE

或者另一个选项（对于大数据集，以避免因内存原因而转换为矩阵）循环遍历列，检查元素是否为空并使用Reduce与&

Reduce(`&`, lapply(df[criticalColumns], function(x) !nzchar(as.character(x))))

一次检查多个数据框列（灵活方式）

1 个答案: