计算每组中的行数 [英] Count number of rows within each group
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问题描述
聚合
函数来计算数据如下: df2 < - aggregate(x〜Year + Month,data = df1,sum)
喜欢计算观察值,但似乎找不到 FUN
的正确参数。直觉上,我以为会如下:
df2< - aggregate(x〜Year + Month,data = df1,计数)
但是,没有这样的运气。
任何想法?
一些玩具数据:
set.seed(2)
df1 < - data.frame(x = 1:20,
Year = sample(2012:2014,20)replace = TRUE )
Month = sample(month.abb [1:3],20,replace = TRUE))
解决方案
还有 df2< - count(x,c('Year','Month'))
(plyr包)
I have a dataframe and I would like to count the number of rows within each group. I reguarly use the aggregate
function to sum data as follows:
df2 <- aggregate(x ~ Year + Month, data = df1, sum)
Now, I would like to count observations but can't seem to find the proper argument for FUN
. Intuitively, I thought it would be as follows:
df2 <- aggregate(x ~ Year + Month, data = df1, count)
But, no such luck.
Any ideas?
Some toy data:
set.seed(2)
df1 <- data.frame(x = 1:20,
Year = sample(2012:2014, 20, replace = TRUE),
Month = sample(month.abb[1:3], 20, replace = TRUE))
解决方案
There is also df2 <- count(x, c('Year','Month'))
(plyr package)
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