根據同一數據框中另一列的值對2列的值進行計數或求和

Question

我有以下數據框：

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)

我想計算2000年和2001年的gender ，並對2002年的weight求和，以創建一個新的數據框，例如：

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

我嘗試了類似的東西：

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

Answer 1

我相信現在我做對了。

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

Answer 2

由於您使用的是邏輯，我認為使用case_when()會很好用。 如果在總結之前設置了邏輯，那么您要做的就是將兩列相加：

library(tidyverse)
library(data.table)
YG %>% 
  mutate(Male = case_when(gender == 'F' ~ 0,
                          year %in% c('2000', '2001') & gender == 'M'~1,
                          TRUE~weight),
         Female = case_when(gender == 'M' ~ 0,
                            year %in% c('2000', '2001') & gender == 'F'~1,
                            TRUE~weight)) %>%
  group_by(year) %>%
  summarize(M = sum(Male),
            F = sum(Female))

這將為您提供所需的內容：

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

Answer 3

一種可能性是預處理您要如何處理“重量”。 本質上，您希望添加2002的權重，而其他年份的權重則增加1。 您可以首先執行以下操作：

YG <- YG %>% add_column(wt = ifelse(year == 2002, weight, 1))

然后，您可以聚合並使用data.table包中的dcast函數重新排列結果。

YG %>% group_by(year, gender) %>% summarise(count = sum(wt)) %>% 
   dcast(formula = year~gender,fun.aggregate = sum,value.var = "count")

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

Answer 4

給定您的數據，您可以使用dcast ：

library(data.table)
setDT(YG)
result <- dcast(YG,  year ~ gender, value.var = 'weight', fun = list(sum, length))
result[, .(year, 
           `F` = c(result$weight_length_F[1:2], result$weight_sum_F[3]),
           M = c(result$weight_length_M[1:2], result$weight_sum_M[3]))]

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

或者，您可以按年份在子集數據集上兩次調用dcast，如下所示：

result2 <- rbindlist(list(
      dcast(YG[year != 2002], year ~ gender, value.var = 'weight', fun = length),
      dcast(YG[year == 2002], year ~ gender, value.var = 'weight', fun = sum)))

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