Question

Dynamic variable naming from dataframe columns

I have a two question test from a pool of several hundred questions. There are two question columns, and two response columns. I need to create new columns named by the question values and assign responses from the corresponding response values

A table of the data is as follows

question1     question2    response1     response2

SI089923       SI089801        B             A

WK090824       WK090712        C             B

WK091040       WK090843        D             C

question1 <- c('SI089923','WK090824','WK091040')
question2 <- c('SI089801','WK090712','WK090843')
response1 <- c('B','C','D')
response2 <- c('A','B','C')

arrayQuestion <-paste( "question", 1:2, sep="")
arrayResponse  <-paste( "response",  1:2, sep="")

I tried code found on this site but got an object not found error

for (i in 1:2){
  varname <- eval(parse(text=paste(arrayQuestion[i], sep="")))
  varvalue <- eval(parse(text=paste(arrayResponse[i], sep="")))
  eval(parse(text=paste(varname, varvalue, sep=" <- ")), envir=.GlobalEnv)
}

Thanks in advance for your help

Answer 1

为了澄清有关最终数据框架形式的问题，列名缩写为字符宽度为五：

ques1 <- c('SI083','WK094','WK090')
ques2 <- c('SI081','WK092','WK093')
resp1 <- c('B','C','D')
resp2 <- c('A','B','C')

初始数据框：

>ques1 ques2 resp1 resp2
>SI083 SI081   'B'   'A'
>WK094 WK092   'C'   'B'
>WK090 WK093   'D'   'C'

最终数据框：

>ques1 ques2 resp1 resp2 SI083 SI081 WK094 WK092 WK090 WK093
>SI083 SI081   'B'   'A'   'B'   'A'
>WK094 WK092   'C'   'B'               'C'   'B'
>WK090 WK093   'D'   'C'                           'D'   'C'

Answer 2

我找到了一个解决方案，虽然我不知道它是否是R中最有效的方法。该程序将读取包含变量名称列和变量值列的数据框，并动态创建基于变量的新列命名并将适用的变量值分配给新列。

names1  <- c('SI923','WK824','WK040') # vector of variable names
names2  <- c('SI801','WK712','WK843') # "
values1 <- c('B','C','D')             # vector of variable values
values2 <- c('A','B','C')             # "

require(reshape2)
dfOne <- data.frame(names1,names2,values1,values2)
print(dfOne)

以下是数据框的打印输出

  names1 names2 values1 values2 
1  SI923  SI801       B       A 
2  WK824  WK712       C       B 
3  WK040  WK843       D       C

以下是编码新变量的代码

namesCol  <-paste( "names",  1:2, sep="") # vector of data frame column names
valuesCol <-paste( "values", 1:2, sep="") # vector of data frame column names

for (j in 1:nrow(dfOne)){
  for (i in 1:length(namesCol)){
    namesCol.i<-eval(namesCol[i])       # data frame column name of variable names
    varname<-eval(parse(text=paste(namesCol.i,'[j]',sep='')))
    if (exists(varname)==FALSE){
      eval(parse(text=paste('dfOne$',varname,'<- NA',sep='')))
    }
    valuesCol.i<-eval(valuesCol[i])     # data frame column name of variable values
    varvalue<-eval(parse(text=paste(valuesCol.i,'[j]',sep='')))
    if (is.character(varvalue)){
      eval(parse(text=paste('dfOne$',varname,'[j]','<-',"'",varvalue,"'",sep='')))
    }else{
      eval(parse(text=paste('dfOne$',varname,'[j]','<-',varvalue,sep='')))
    }
  }
}  
print(dfOne)

以下是带有新编码变量的数据框的打印输出

  names1 names2 values1 values2 SI923 SI801 WK824 WK712 WK040 WK843
1  SI923  SI801       B       A     B     A  <NA>  <NA>  <NA>  <NA>
2  WK824  WK712       C       B  <NA>  <NA>     C     B  <NA>  <NA>
3  WK040  WK843       D       C  <NA>  <NA>  <NA>  <NA>     D     C

r dynamic variable naming from dataframe columns

2 个答案: