Question

我需要比较两个数据帧并生成比较结果的输出。尺寸相同。列和行顺序匹配。我想比较两个数据帧之间的每个相应单元格，并确定它们是包含相同的值还是不同的值。如果值不同，我需要知道两个值是否属于我定义的特定向量，或者它们是否来自2个不同的向量。我在下面提供了示例代码。

我无法在论坛中发现任何我需要的东西，主要是因为我需要知道值何时不同，它们根据我提供的标准有多么不同。

#Possible Value Types for the Data Frames
typeA = c("Green", "Blue", "Purple")
typeB = c("Red", "Orange", "Yellow")

#Create Data Frames to Compare
df1 = as.data.frame(cbind(rbind("Green","Red","Yellow"), 
            rbind("Green", "Purple", "Red"), 
            rbind("Orange", "Orange",NA), 
            rbind(NA,"Red","Purple")))

df2 = as.data.frame(cbind(rbind("Green","Red","Yellow"), 
                          rbind(NA, "Purple", "Yellow"), 
                          rbind("Blue", "Orange",NA), 
                          rbind("Blue","Red","Green")))

#Data frames compared must have identical dimensions
###INSERT FUNCTION HERE
myfunction = function(df1,df2){
  #compare corresponding cells and provide output based on match
  #example: compare cell df1[1,1] to df2[1,1]
  #if either df1[1,1] or df2[1,1] is NA then return NA, else...
    #if df1[1,1] matches df2[1,1] then return "Match"
    #if df1[1,1] does not match df2[1,1] but they are both in vector typeB then return "SAMEGROUP"
    #if df1[1,1] does not match df2[1,1] and one is in vector typeA and the other in typeB then return "DIFFGROUP"
}

###RUN FUNCTION
df.out = myfunction(df1,df2)

#expected output
#Match: The values in df1 and df2 for that cell are identical
#SAMEGROUP: The values in df1 and df2 for that cell are different, but
##they come from the same group (typeA or typeB)
#DIFFGROUP: The values in df1 and df2 for that cell are different, and
##they come from different groups (one from typeA, one from typeB)
#NA: One or both of the corresponding cells in df1 or df2 has an NA

df.out = as.data.frame(cbind(rbind("Match","Match","Match"), 
                          rbind(NA, "Match", "SAMEGROUP"), 
                          rbind("DIFFGROUP", "Match",NA), 
                          rbind(NA,"Match","SAMEGROUP")))

谢谢！

Answer 1

谢谢jarfa的建议。这让我走上正轨。这就行了。

df1 = as.matrix(df1)
df2 = as.matrix(df2)

#ifelse(df1==df2, "match","diff") #test

ifelse(df1==df2, "Match", 
       ifelse(df1 %in% typeA & df2 %in% typeA,"SAMEGROUP",
              ifelse(df1 %in% typeB & df2 %in% typeB, "SAMEGROUP",
                     ifelse(df1 %in% typeA & df2 %in% typeB,"DIFFGROUP",
                            ifelse(df1 %in% typeB & df2 %in% typeA, "DIFFGROUP","TRYAGAIN")))))

Answer 2

首先，要强制执行维度条件：

stopifnot(all.equal(dim(df1), dim(df2)))

对于你的功能：一个天真，缓慢的方法将是这样的：

for(i in 1:dim(df1)[1])
  for(j in 1:dim(df1)[2])
    #complicated ifelse statement(s)

但这很容易被矢量化。参见：

a = matrix(1:9, 3)
b = matrix(c(1:8, -1),3)
ifelse(a == b, 'match', 'nomatch')

你的if / else肯定会更复杂，但我想你可以从中找出答案。它将是一些嵌套的ifelse（）函数

编辑：创建一个将返回给定值组的函数。然后，声明

groupfun(a) == groupfun(b)

应该只返回TRUES和FALSES矩阵，这将很容易使用。

比较数据框中的值并返回结果

2 个答案: