r - 根据同一数据框中另一列的值对 2 列的值进行计数或求和

Question

我有下面的数据框:

year<-c("2000","2000","2001","2002","2000","2002")
gender<-c("M","F","M","F","M","M")
weight<-c(0.5,0.7,0.8,0.7,0.6,0.9)
YG<-data.frame(year,gender,weight)

我想计算 2000 年和 2001 年的性别，并对 2002 年的权重求和，以便创建一个新的数据框，例如:

year   M   F
1 2000 2.0 1.0
2 2001 1.0 0.0
3 2002 0.9 0.7

我尝试过类似的方法:

library(tidyverse)
YG %>%
  group_by(year) %>%
  summarise(sum(weight[year=="2002"]))%>%
  count(round(gender[year!="2002"])) %>%
  spread(gender, n, fill = 0)

Answer 1

我相信现在我做对了。

library(tidyverse)

YG %>%
  group_by(year, gender) %>%
  summarise(n = sum(weight),
            g = n()) %>%
  mutate(n = ifelse(year == 2002, n, g)) %>%
  select(-g) %>%
  spread(gender, n, fill = 0)
## A tibble: 3 x 3
## Groups:   year [3]
#  year      F     M
#  <fct> <dbl> <dbl>
#1 2000    1     2  
#2 2001    0     1  
#3 2002    0.7   0.9