##generate test data
mtcars <- mtcars
mtcars$meanmpg <- mean(mtcars$mpg)
现在我希望生成一个 numpoints 列,用于表示组内超出平均值 -2 和 + 5 范围的点数。
mutated <- mtcars %>% group_by(cyl) %>%
mutate(numpoints = length( which( .$mpg < (.$meanmpg - 2) | .$mpg > (.$meanmpg + 5) ) ) )
例如,我会在列 numpoints 中看到“4 圆柱组”为 6,而“6 圆柱组”为 1。 (小于平均英里数 - 2 或大于平均英里数 + 5)
有什么想法吗?我也尝试过过滤器,但无法找到一种方法来保留过滤器后的所有数据。
最佳答案
Now I wish to generate a column numpoints for the number of points within a group that fall outside -2 and + 5 of the mean.
我会尝试
library(dplyr)
mtcars %>%
group_by(cyl) %>%
mutate(numpoints = sum(!between(mpg, meanmpg-2, meanmpg+5)))
# Source: local data frame [32 x 13]
# Groups: cyl [3]
#
# mpg cyl disp hp drat wt qsec vs am gear carb meanmpg numpoints
# <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <int>
# 1 21.0 6 160.0 110 3.90 2.620 16.46 0 1 4 4 20.09062 1
# 2 21.0 6 160.0 110 3.90 2.875 17.02 0 1 4 4 20.09062 1
# 3 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1 20.09062 6
# 4 21.4 6 258.0 110 3.08 3.215 19.44 1 0 3 1 20.09062 1
# 5 18.7 8 360.0 175 3.15 3.440 17.02 0 0 3 2 20.09062 12
# 6 18.1 6 225.0 105 2.76 3.460 20.22 1 0 3 1 20.09062 1
# 7 14.3 8 360.0 245 3.21 3.570 15.84 0 0 3 4 20.09062 12
# 8 24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 2 20.09062 6
# 9 22.8 4 140.8 95 3.92 3.150 22.90 1 0 4 2 20.09062 6
# 10 19.2 6 167.6 123 3.92 3.440 18.30 1 0 4 4 20.09062 1
# .. ... ... ... ... ... ... ... ... ... ... ... ... ...
关于r - 查找组内超出阈值的点数,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/38232846/