Question

我在两列中有数据：它的日期和一个因子变量。我的数据片段：

           Date Category
1    2009-06-22    BREAD
2    2009-06-23    BREAD
3    2009-06-23    BREAD
4    2009-06-23      JAM
5    2009-06-23     MILK
6    2009-06-24    BREAD
9    2009-06-24     MILK
10   2009-06-25      JAM

问题：我需要计算每年每个月出现的每种Category类型有多少种。

I tried approaches like this，使用aggregate，但我不知道该如何拟合因子变量。

数据示例：这是一个可行的数据示例（具有更多的月份和年份）：http://rextester.com/DYMXN47464当然，我的最终（实际）数据是从2009年到2018年，每个月每年，但这些观测值太多了，我无法共享整个数据。

Answer 1

基于您的数据集。将年份和月份添加到数据中，按年份，月份和类别分组并计算结果。

library(dplyr)
library(lubridate)

data %>% mutate(year = year(Date),
                month = month(Date)) %>% 
  group_by(year, month, Category) %>%
  summarise(count = n())

# A tibble: 11 x 4
# Groups:   year, month [?]
    year month Category count
   <dbl> <dbl> <fct>    <int>
 1  2009     6 MILK         2
 2  2009     6 BREAD        6
 3  2009     6 JAM          2
 4  2010     4 MILK         2
 5  2010     4 BREAD        7
 6  2010     4 JAM          2
 7  2011    12 MILK         4
 8  2011    12 BREAD       13
 9  2011    12 JAM          1
10  2012     1 MILK         1
11  2012     1 BREAD        2

数据：

data <- structure(list(Date = structure(c(14417, 14418, 14418, 14418, 
14418, 14419, 14419, 14419, 14419, 14420, 14725, 14725, 14726, 
14726, 14726, 14726, 14727, 14727, 14727, 14727, 14728, 15335, 
15335, 15335, 15335, 15336, 15336, 15336, 15336, 15337, 15337, 
15337, 15337, 15338, 15338, 15338, 15338, 15339, 15339, 15342, 
15342, 15342), class = "Date"), Category = structure(c(2L, 2L, 
2L, 3L, 1L, 2L, 2L, 2L, 1L, 3L, 2L, 2L, 2L, 1L, 2L, 2L, 3L, 3L, 
1L, 2L, 2L, 2L, 2L, 2L, 1L, 2L, 1L, 1L, 1L, 3L, 2L, 2L, 2L, 2L, 
2L, 2L, 2L, 2L, 2L, 2L, 2L, 1L), .Label = c("MILK", "BREAD", 
"JAM", "SALTO DE BANCA"), class = "factor")), row.names = c(1L, 
2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L, 1000L, 1001L, 1002L, 1003L, 
1004L, 1005L, 1006L, 1007L, 1008L, 1009L, 1010L, 3000L, 3001L, 
3002L, 3003L, 3004L, 3005L, 3006L, 3007L, 3008L, 3009L, 3010L, 
3011L, 3012L, 3013L, 3014L, 3015L, 3016L, 3017L, 3018L, 3019L, 
3020L), class = "data.frame")

Answer 2

我们还可以将Date类转换为yearmon（从zoo）并获得count

library(zoo)
library(dplyr)
data %>% 
     count(yearmon = as.yearmon(Date), Category)
# A tibble: 11 x 3
#   yearmon       Category     n
#   <S3: yearmon> <fct>    <int>
# 1 Jun 2009      MILK         2
# 2 Jun 2009      BREAD        6
# 3 Jun 2009      JAM          2
# 4 Apr 2010      MILK         2
# 5 Apr 2010      BREAD        7
# 6 Apr 2010      JAM          2
# 7 Dec 2011      MILK         4
# 8 Dec 2011      BREAD       13
# 9 Dec 2011      JAM          1
#10 Jan 2012      MILK         1
#11 Jan 2012      BREAD        2

注意：数据来自@phiver的帖子

每年按月计算因子水平

2 个答案: