Question

我有以下data.frame df1 ，我在R中创建了因子 fac1 ，我将它作为参数传递给Rcpp函数。请求的任务是获取Rcpp函数中的所有因子级别并使用它们。

fac1 <- factor(x = sample(x = 1:5,size = 100,replace = T),labels =  paste0("D",1:5))
var1 <- sample(x = 1:20,size = 100,replace = T)
fac2 <- factor(x = sample(x = 1:12,size = 100,replace = T),labels =  paste0("M",1:12))
df1 <- data.frame(fac1,var1,fac2)

Answer 1

经过一番研究后，我找到了一个解决方案，我正在分享它 Rf_isFactor 检查data.frame列是否是一个因素相应 IntegerVector （tempVec）的级别属性返回因子级别。

cppFunction("void GetFactorLevels(DataFrame df1){
    CharacterVector varNames = df1.names();
    for(int i=0; i<df1.length();i++) {
        if(Rf_isFactor(df1[i])==1){
           IntegerVector tempVec=df1[i];
           CharacterVector factorLevels =tempVec.attr(\"levels\");
           Rcout<<varNames[i]<<\": \"<<factorLevels<<std::endl;
        }
   }
}")

> GetFactorLevels(df1)
fac1: "D1" "D2" "D3" "D4" "D5"
fac2: "M1" "M2" "M3" "M4" "M5" "M6" "M7" "M8" "M9" "M10" "M11" "M12"

当Rcpp作为参数从R传递时，如何访问Rcpp中data.frame的因子级别？

1 个答案: