r - R:如何删除仅一(二、三)列中与另一行不同的行?
问题描述
我有一个类似于以下示例的数据框。有时,行包含与另一行中的对象相同的信息,除了一个(或多个)列包含“NA”。我只想要包含尽可能多信息的行,所以我想删除所有包含“NA”但与另一行具有相同信息的行。“NA”可能在 C 或 D 列或两者中(从不在 A 或 B 中)。如果没有“更准确”的行,则必须保留包含“NA”的行。
我已经尝试过使用 for 循环(参见示例)并且它有效,第 1 行和第 6 行将被删除。但是,我必须对其进行调整以检查 C 列,并且在我的真实数据中我有更多列,因此有更多可能的组合,这使得该解决方案不切实际并且可能导致错误。
有没有其他方法可以轻松解决这个问题?谢谢!
df <- rbind(data.frame(A = "obj1", B = "1", C = "2", D = "NA"),
data.frame(A = "obj1", B = "1", C = "2", D = "3"),
data.frame(A = "obj2", B = "1", C = "NA", D = "3"),
data.frame(A = "obj2", B = "1", C = "2", D = "3"),
data.frame(A = "obj2", B = "3", C = "2", D = "3"),
data.frame(A = "obj2", B = "3", C = "2", D = "NA"),
data.frame(A = "obj3", B = "2", C = "4", D = "6"),
data.frame(A = "obj4", B = "2", C = "NA", D = "NA"))
toBeDeleted <- c(55)
for (i in 1:nrow(df)){
thisRow <- df[i,]
if (thisRow$D == "NA"){
for (j in i:nrow(subset(df, A == thisRow$A))){
anotherRow <- df[j,]
if (anotherRow$A == thisRow$A & anotherRow$B == thisRow$B
& anotherRow$C == thisRow$C & anotherRow$D != thisRow$D){
toBeDeleted <- c(toBeDeleted,i)
}
}
}
}
df2 <- df[-toBeDeleted,]
解决方案
我们可以使用duplicated(df[1:2])
和的duplicated(df[1:2], fromLast = TRUE)
组合rowSums(is.na(df)) > 0
来排除所有NA
重复的行:
df <- rbind(data.frame(A = "obj1", B = "1", C = "2", D = NA),
data.frame(A = "obj1", B = "1", C = "2", D = "3"),
data.frame(A = "obj2", B = "1", C = NA, D = "3"),
data.frame(A = "obj2", B = "1", C = "2", D = "3"),
data.frame(A = "obj2", B = "3", C = "2", D = "3"),
data.frame(A = "obj2", B = "3", C = "2", D = NA),
data.frame(A = "obj3", B = "2", C = "4", D = "6"),
data.frame(A = "obj4", B = "2", C = NA, D = NA))
df[!((duplicated(df[1:2]) | duplicated(df[1:2], fromLast = TRUE)) & rowSums(is.na(df)) > 0),]
A B C D
2 obj1 1 2 3
4 obj2 1 2 3
5 obj2 3 2 3
7 obj3 2 4 6
8 obj4 2 <NA> <NA>
它是一个简单的子集,因此不需要循环,即使有大量数据也非常快。它是这样工作的:
我们调用数据df[]
并排除!()
前两列有重复df[1:2]
且至少有一个NA
值的所有行rowSums(is.na(df)) > 0
。为此,您需要真实NA
的数据,而不是character
"NA"
上面示例数据中的数据。如果您只有"NA"
,请rowSums(df == "NA") > 0
改用。