如何基于值向量对R中的数据帧中的行进行子集化? [英] How can I subset rows in a data frame in R based on a vector of values?
问题描述
我有两个数据集，它们本来应该是相同的大小，但不一样.我需要修剪A中不在B中的值，反之亦然，以便从要进入报表的图形中消除噪声. (不用担心，该数据不会被永久删除！)
I have two data sets that are supposed to be the same size but aren't. I need to trim the values from A that are not in B and vice versa in order to eliminate noise from a graph that's going into a report. (Don't worry, this data isn't being permanently deleted!)
我已阅读以下内容:
- Selecting columns in R data frame based on those *not* in a vector
- http://www.ats.ucla.edu/stat/r/faq/subset_R.htm
- How to combine multiple conditions to subset a data-frame using "OR"?
但是我仍然无法使它正常工作.这是我的代码:
But I'm still not able to get this to work right. Here's my code:
bg2011missingFromBeg <- setdiff(x=eg2011$ID, y=bg2011$ID)
#attempt 1
eg2011cleaned <- subset(eg2011, ID != bg2011missingFromBeg)
#attempt 2
eg2011cleaned <- eg2011[!eg2011$ID %in% bg2011missingFromBeg]
第一次尝试只是消除结果setdiff向量中的第一个值.第二次尝试会产生笨拙的错误:
The first try just eliminates the first value in the resulting setdiff vector. The second try yields and unwieldy error:
Error in `[.data.frame`(eg2012, !eg2012$ID %in% bg2012missingFromBeg)
: undefined columns selected
推荐答案
这将为您提供所需的内容:
This will give you what you want:
eg2011cleaned <- eg2011[!eg2011$ID %in% bg2011missingFromBeg, ]
第二次尝试中的错误是因为您忘记了,
The error in your second attempt is because you forgot the ,
通常，为了方便起见，规范object[index]将2d object的列作为子集.如果要对行进行子集并保留所有列，则必须使用规范
object[index_rows, index_columns]，而index_cols可以保留为空白，默认情况下将使用所有列.
In general, for convenience, the specification object[index] subsets columns for a 2d object. If you want to subset rows and keep all columns you have to use the specification
object[index_rows, index_columns], while index_cols can be left blank, which will use all columns by default.
但是，您仍然需要包含,来表示您想要获取行的子集而不是列的子集.
However, you still need to include the , to indicate that you want to get a subset of rows instead of a subset of columns.
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