r 在 dcast 之后计算行中的值答案

【问题标题】：r count values in rows after dcastr 在 dcast 之后计算行中的值
【发布时间】：2020-12-24 10:28:14
【问题描述】：

在从reshape2 包执行dcast 操作后，我想sum 数据帧行中的所有值。问题是所有值都相同（10）并且是所有行的总和。值应该是 4,2,4 带代码的示例数据：

df <- data.frame(x = as.factor(c("A","A","A","A","B","B","C","C","C","C")),
                 y = as.factor(c("AA","AB","AA","AC","BB","BA","CC","CC","CC","CD")),
                 z = c("var1","var1","var2","var1","var2","var1","var1","var2","var2","var1"))

df2 <- df %>%
  group_by(x,y) %>%
  summarise(num = n()) %>%
  ungroup()

df3 <- dcast(df2,x~y, fill = 0 )

df3$total <- sum(df3$AA,df3$AB,df3$AC,df3$BA,df3$BB,df3$CC,df3$CD)

【问题讨论】：

标签： r dplyr reshape2

【解决方案1】：

sum 为您提供 1 个组合值，并且该值对所有其他行重复。

sum(df3$AA,df3$AB,df3$AC,df3$BA,df3$BB,df3$CC,df3$CD)
#[1] 10

您需要rowSums 来分别获取每一行的总和。

df3$total <- rowSums(df3[-1])

这是一个简化的tidyverse 方法，从df 开始：

library(dplyr)
library(tidyr)

df %>%
  count(x, y, name = 'num') %>%
  pivot_wider(names_from = y, values_from = num, values_fill = 0) %>%
  mutate(total = rowSums(select(., AA:CD)))

#  x        AA    AB    AC    BA    BB    CC    CD total
#  <fct> <int> <int> <int> <int> <int> <int> <int> <dbl>
#1 A         2     1     1     0     0     0     0     4
#2 B         0     0     0     1     1     0     0     2
#3 C         0     0     0     0     0     3     1     4

【讨论】：

【解决方案2】：

我们可以在pivot_wider 中指定values_fn，也可以从janitor 中使用adorn_totals

library(dplyr)
library(tidyr)
library(janitor)
df %>% 
   pivot_wider(names_from = y, values_from = z, values_fill = 0, 
         values_fn = length) %>%
   adorn_totals("col")

-输出

# x AA AB AC BB BA CC CD Total
# A  2  1  1  0  0  0  0     4
# B  0  0  0  1  1  0  0     2
# C  0  0  0  0  0  3  1     4

或将base R 与xtabs 和addmargins 一起使用

addmargins(xtabs(z ~ x + y, transform(df, z = 1)), 2)
#   y
#x   AA AB AC BA BB CC CD Sum
#  A  2  1  1  0  0  0  0   4
#  B  0  0  0  1  1  0  0   2
#  C  0  0  0  0  0  3  1   4

【讨论】：