R Dataframe - 如何计算到某一点的行数？

Question

我目前的数据看起来像这样:

1   Saturday  Evening             16.2  235.84
2   Saturday  Evening             23.4  235.29
3   Saturday  Evening             29.4  232.79
4   Sunday   Evening             24.2  233.89
5   Sunday   Evening             24.2  233.66
6   Sunday   Evening             24.2  233.38
7   Sunday   Evening             24.2  232.99
8   Sunday   Evening             25.4  233.21
9   Sunday   Evening             26.8  232.37
10  Saturday    Night            25.6  231.55
11  Saturday     Night           24.4  231.19
12  Saturday     Night           24.4  231.63
13  Saturday     Night           24.4  231.71
14  Sunday     Night             25.2  231.23
15  Sunday     Night             25.2  231.23
14  Saturday     Night             25.2  231.23
15  Saturday    Night             25.2  231.23
15  Sunday    Night             25.2  231.23

df = structure(list(V2 = c("Saturday", "Saturday", "Saturday", "Sunday", 
"Sunday", "Sunday", "Sunday", "Sunday", "Sunday", "Saturday", 
"Saturday", "Saturday", "Saturday", "Sunday", "Sunday", "Saturday", 
"Saturday", "Sunday"), V3 = c("Evening", "Evening", "Evening", 
"Evening", "Evening", "Evening", "Evening", "Evening", "Evening", 
"Night", "Night", "Night", "Night", "Night", "Night", "Night", 
"Night", "Night"), V4 = c(16.2, 23.4, 29.4, 24.2, 24.2, 24.2, 
24.2, 25.4, 26.8, 25.6, 24.4, 24.4, 24.4, 25.2, 25.2, 25.2, 25.2, 
25.2), V5 = c(235.84, 235.29, 232.79, 233.89, 233.66, 233.38, 
232.99, 233.21, 232.37, 231.55, 231.19, 231.63, 231.71, 231.23, 
231.23, 231.23, 231.23, 231.23)), .Names = c("V2", "V3", "V4", 
"V5"), row.names = c(NA, -18L), class = "data.frame")

数据仅包括周六和周日，因此它不是连续的(例如，上周日和下周六/工作日开始之间的数据缺失)。每个周末的数据数量各不相同，因此我需要计算每个星期六星期日集合中有多少观察值。假设数据从周六到周日开始，然后又到下一组周六周日，我如何统计每组数据并将其存储在一个向量中？

编辑:例如，使用上面的数据，我想要的输出将是一个包含以下值的向量:[9, 6, 3]

Answer 1

使用 dplyr 解决方案，其中 V2 是您当前的天数列:

library(dplyr)
df %>%
  mutate(x = lag(cumsum((V2 == 'Sunday' & lead(V2) == 'Saturday')), default = 0)) %>%
  group_by(x) %>%
  summarise(z = n()) %>%
  select(z)

这产生

      z
  <int>
1     9
2     6
3     3