R - 检查矢量对其他矢量的元素 [英] R - check elements of vector against other vector
问题描述
考虑这些数据框:
A = data.frame(par = c('long A story','long C story','blabla D'),val = 1:3)
B = data.frame(par = c('Z','D','A'),val = letters [1:3])
B列'par'的每个元素应与A列par相匹配。
如果有匹配的话,应该在A中标注。
[这会给出一列用于合并A和B的公共值。]
<因此,希望得到的结果是:
$ $ $ $ $ $ $ $ $ $ A $变换(A,label = c('A','NA', 'D'))
这怎么办?
Henk
要做你想要的东西,试试
A = data.frame(par = c('long A story','long C story','blabla D'),val = 1:3)
B = data.frame(par = c('Z','D','A'),val = letters [1:3])
A $ label < - NA
for(x in B $ par){
is.match< - lapply(A $ par,function(y)grep(x,y))
A $ label [which(is.match> ; 0)] <-x
}
(我假设你的意思是大写A在你的例子中 A = transform(a,label = c('A','NA','D'))
;在这种情况下,它们完全匹配)。编辑:我看到你做了编辑。他们确实匹配。
上述方法仅适用于只有一个B适合每个A的情况(换句话说,可以有多个对B而言不是多个B到A)。这是因为你在输出中需要的结构。
I would like to match the elements of a column in a dataframe against another dataframe.
Consider these dataframes:
A=data.frame(par=c('long A story','long C story', 'blabla D'),val=1:3)
B=data.frame(par=c('Z','D','A'),val=letters[1:3])
Each element of B column 'par' should be matched against A column par. If there is a match, it should be labeled in A. [This then gives a column of common values for merging A and B].
The desired result is therefore:
A=transform(A,label=c('A','NA','D'))
How can this be done?
Henk
To do what you're asking for, try
A=data.frame(par=c('long A story','long C story', 'blabla D'),val=1:3)
B=data.frame(par=c('Z','D','A'),val=letters[1:3])
A$label <- NA
for (x in B$par){
is.match <- lapply(A$par,function(y) grep(x, y))
A$label[which(is.match > 0)] <- x
}
(I assumed you meant a capital A in your example A=transform(a,label=c('A','NA','D'))
; in that case, these match exactly). EDIT: I see you made that edit. They do match then.
The above method will work only if there is exactly one B that fits every A (in other words, there can be multiple As to a B but not multiple Bs to an A). This is because of the structure you want in the output.
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