使用$和列名称向量动态选择数据框列

Question

使用$和列名称向量动态选择数据框列

我希望根据不同的列来订购数据框，一个转弯。我有一个字符向量，其中的相关列名order应该基于：

parameter <- c("market_value_LOCAL", "ep", "book_price", "sales_price", "dividend_yield",

               "beta", "TOTAL_RATING_SCORE", "ENVIRONMENT", "SOCIAL", "GOVERNANCE")

我想循环遍历名称parameter并动态选择要用于order我的数据的列：

Q1_R1000_parameter <- Q1_R1000[order(Q1_R1000$parameter[X]), ]

这里X是1:10（因为我有10个项目parameter）。

为了使我的示例可重现，请考虑mtcars存储在字符向量中的数据集和一些变量名称cols。当我尝试mtcars使用动态子集选择变量时cols，以与上面（Q1_R1000$parameter[X]）类似的方式，未选择该列：

cols <- c("cyl", "am")

mtcars$cols[1]

# NULL

Answer 1

如果我理解正确，你有一个包含变量名称的向量，并希望遍历每个名称并按它们对数据框进行排序。如果是这样，这个例子应该为您说明一个解决方案。你的主要问题（完整的例子不完整，所以我不确定你可能缺少什么）是它应该是，order(Q1_R1000[,parameter[X]])而不是order(Q1_R1000$parameter[X])，因为参数是一个外部对象，包含一个与直接列相对的变量名您的数据框（当$适当时）。set.seed(1)dat <- data.frame(var1=round(rnorm(10)),&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;var2=round(rnorm(10)),&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;var3=round(rnorm(10)))param <- paste0("var",1:3)dat#&nbsp; &nbsp;var1 var2 var3#1&nbsp; &nbsp; -1&nbsp; &nbsp; 2&nbsp; &nbsp; 1#2&nbsp; &nbsp; &nbsp;0&nbsp; &nbsp; 0&nbsp; &nbsp; 1#3&nbsp; &nbsp; -1&nbsp; &nbsp;-1&nbsp; &nbsp; 0#4&nbsp; &nbsp; &nbsp;2&nbsp; &nbsp;-2&nbsp; &nbsp;-2#5&nbsp; &nbsp; &nbsp;0&nbsp; &nbsp; 1&nbsp; &nbsp; 1#6&nbsp; &nbsp; -1&nbsp; &nbsp; 0&nbsp; &nbsp; 0#7&nbsp; &nbsp; &nbsp;0&nbsp; &nbsp; 0&nbsp; &nbsp; 0#8&nbsp; &nbsp; &nbsp;1&nbsp; &nbsp; 1&nbsp; &nbsp;-1#9&nbsp; &nbsp; &nbsp;1&nbsp; &nbsp; 1&nbsp; &nbsp; 0#10&nbsp; &nbsp; 0&nbsp; &nbsp; 1&nbsp; &nbsp; 0for(p in rev(param)){&nbsp; &nbsp;dat <- dat[order(dat[,p]),]&nbsp;}dat#&nbsp; &nbsp;var1 var2 var3#3&nbsp; &nbsp; -1&nbsp; &nbsp;-1&nbsp; &nbsp; 0#6&nbsp; &nbsp; -1&nbsp; &nbsp; 0&nbsp; &nbsp; 0#1&nbsp; &nbsp; -1&nbsp; &nbsp; 2&nbsp; &nbsp; 1#7&nbsp; &nbsp; &nbsp;0&nbsp; &nbsp; 0&nbsp; &nbsp; 0#2&nbsp; &nbsp; &nbsp;0&nbsp; &nbsp; 0&nbsp; &nbsp; 1#10&nbsp; &nbsp; 0&nbsp; &nbsp; 1&nbsp; &nbsp; 0#5&nbsp; &nbsp; &nbsp;0&nbsp; &nbsp; 1&nbsp; &nbsp; 1#8&nbsp; &nbsp; &nbsp;1&nbsp; &nbsp; 1&nbsp; &nbsp;-1#9&nbsp; &nbsp; &nbsp;1&nbsp; &nbsp; 1&nbsp; &nbsp; 0#4&nbsp; &nbsp; &nbsp;2&nbsp; &nbsp;-2&nbsp; &nbsp;-2