Question

我有一个包含行索引号的向量，我希望根据这些数字创建一个新的虚拟变量，即向量中存在的行在新变量中的值为1。我在循环中尝试这个，我需要新的变量名来包含循环变量的值。问题似乎是我无法为该变量分配任何值，除非它存在，但我也无法创建它。

以下是一些伪数据和命令的示例。

set.seed(100)
df <- data.frame(id = 1:20, 
                 year = sample(2011:2013, 20, replace = TRUE), 
                 dum = sample(0:1, 20, rep = TRUE), 
                 var = sample(10:99, 20))
for (x in 2011:2013) {
# Below I take a subset of data to test models for different years.
  assign(paste0("subset.", x), df[df$year == x, ])
  # Here I would test a model.
# Below I imitate matching of propensity scores and create an object that contains 
# row indexes of control group.
  set.seed(x)
  assign(paste0("matching.", x), list(data = df, index.control = sample(1:20, 4)))
# Below I attempt to take the row indexes ofcontrol goup from the created 'matching' object and create 
# a new dummy variable that determines the control group. None of the commands work.
  assign(get(paste0("subset.", x))[get(paste0("matching.", x))$index.control, paste0("control.", x)], 1)
  get(paste0("subset.", x))[get(paste0("matching.", x))$index.control, paste0("control.", x)] <- 1
  get(paste0("subset.", x))[[get(paste0("matching.", x))$index.control, paste0("control.", x)]] <- 1
}

以下是运行最后三个命令时显示的错误。

> assign(get(paste0("subset.", x))[get(paste0("matching.", x))$index.control, paste0("control.", x)], 1)
Error in assign(get(paste0("subset.", x))[get(paste0("matching.", x))$index.control,  : 
  invalid first argument

> get(paste0("subset.", x))[get(paste0("matching.", x))$index.control, paste0("control.", x)] <- 1
Error in get(paste0("subset.", x))[get(paste0("matching.", x))$index.control,  : 
  target of assignment expands to non-language object

> get(paste0("subset.", x))[[get(paste0("matching.", x))$index.control, paste0("control.", x)]] <- 1
Error in get(paste0("subset.", x))[[get(paste0("matching.", x))$index.control,  : 
  target of assignment expands to non-language object

因此，我的目标是创建一个新的＆＃34;虚拟＆＃34;包含循环变量名称的变量，并将1的值赋给它，其中行号与get(paste0("matching.", x))$index.control中的数字匹配。

Answer 1

考虑使用lapply存储匹配索引和子集化数据帧的应用解决方案，然后使用mapply对它们运行所需的值操作。完成后，使用assign()输出到多个对象。

# LIST OF YEARLY DATAFRAMES
subsetdfs <- lapply(2011:2013, function(x) df[df$year == x,])

# LIST OF YEARLY RANDOM IDS
matchinglists <- lapply(2011:2013, function(x) {
                                     set.seed(x)
                                     sample(1:20, 4)
                                  }
                        )

# USER-DEFINED FUNCTION TO ASSIGN NAMED COLUMN AND VALUE
dfprocess <- function(x, y){
                x['control'] <- NA
                x[y,'control'] <- 1
                x <- x[!is.na(x$id),]
                return(x)
             }

# MAPPLY TO MAP ITERATIVELY EACH LIST FOR FCT
dflist <- mapply(dfprocess, x=subsetdfs, y=matchinglists)
dflist    
#         [,1]      [,2]      [,3]     
# id      Integer,6 Integer,9 Integer,5
# year    Integer,6 Integer,9 Integer,5
# dum     Integer,6 Integer,9 Integer,5
# var     Integer,6 Integer,9 Integer,5
# test    Numeric,6 Numeric,9 Numeric,5
# control Numeric,6 Numeric,9 Numeric,5

# CREATE MULTIPLE FINAL DFS
for (i in 2011:2013) {
      assign(paste0('subset', i), 
             data.frame(dflist[, i - 2010]),
             envir = .GlobalEnv)
}

如何创建一个名称包含变量名称的新列（在循环中）？

1 个答案: