根据R中2列中的值选择特定行

我有一个大型数据集的GPS衣领位置，每天有不同数量的位置。我想分开只收集一个位置的日子，并创建一个包含所有信息的新数据框。

I have a large data set of GPS collar locations that have a varying number of locations each day. I want to separate out only the days that have a single location collected and make a new data frame containing all their information.

month    day    easting    northing    time    ID
  6       1     #######    ########    0:00    ##
  6       2     #######    ########    6:00    ##
  6       2     #######    ########    0:00    ##
  6       3     #######    ########    18:00   ##
  6       3     #######    ########    12:00   ##
  6       4     #######    ########    0:00    ##
  6       5     #######    ########    6:00    ##

目前我已经集合了一些东西，但是不能进入下一步。

Currently I have hashed together something, but can't quite get to the next step.

library(plyr)
dog<-count(data1,vars=c("MONTH","day"))
datasub1<-subset(dog,freq==1)

这给我一个读数，看起来像

This gives me a readout that looks like

    MONTH day freq
1       6  29    1
7       7   5    1
8       7   6    1
10      7   8    1
12      7  10    1

我尝试使用月份和日期的值包含来自主数据集的行，以便我可以创建一个仅包含频率为1但包含所有关联数据的点的数据框。我已经到了这一步：

I am trying to use the values of the Month and day to pull out the rows that contain them from the main dataset so that I can make a data frame containing only the points with a frequency of 1 but that contains all the associated data. I've got to this point:

sis<-c(datasub1$MONTH)
bro<-c(datasub1$day)
datasub2<-subset(data1,MONTH==sis&day==bro)

$ b b

...但是这不会给我任何东西，个人而言，它使直觉有意义（R初学者），它应该包含两个值的兄弟和sis的行。

... but that doesn't give me anything, personally it makes intuitive sense (R beginner) that it should subset out the rows that contain both the values of bro and sis.

任何帮助将非常感激。