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r - 当我已经有了单元格值时，如何在 R 中创建表或命名数组？

问题描述

给定一个数据框，例如：

df = data.frame(
  Bread=rep(c("White", "Wheat", "Rye"), each=4),
  Meat=rep(c("Ham", "Roast Beef", "Turkey", "Pastrami"), times=3),
  Price=rnorm(12)
)
df
#>    Bread       Meat      Price
#> 1  White        Ham  0.6428015
#> 2  White Roast Beef -0.4382468
#> 3  White     Turkey -0.9383151
#> 4  White   Pastrami  1.6069649
#> 5  Wheat        Ham -0.9898017
#> 6  Wheat Roast Beef  0.4567167
#> 7  Wheat     Turkey  0.9479741
#> 8  Wheat   Pastrami -0.5721409
#> 9    Rye        Ham  0.1234204
#> 10   Rye Roast Beef -1.1446393
#> 11   Rye     Turkey -2.8622073
#> 12   Rye   Pastrami -1.1646482

由reprex 包于 2020-06-02 创建(v0.3.0)

我想制作一张这样的表格，但里面填满了这些值。

+-------+-----+--------+------------+----------+
|       | Ham | Turkey | Roast Beef | Pastrami |
+-------+-----+--------+------------+----------+
| White |     |        |            |          |
+-------+-----+--------+------------+----------+
| Wheat |     |        |            |          |
+-------+-----+--------+------------+----------+
| Rye   |     |        |            |          |
+-------+-----+--------+------------+----------+

之后，我想添加诸如“面包类型”和“肉类选择”之类的暗名。

我尝试使用spread，但我不知道如何将最终数据框转换为表格对象。

tidyr::spread(df, Bread, Price)
#>         Meat        Rye      Wheat      White
#> 1        Ham  1.4325955  0.2399214 -1.3911592
#> 2   Pastrami  0.3127256  0.1133108  0.1940318
#> 3 Roast Beef -1.6286526  0.8210128 -0.4017497
#> 4     Turkey -0.8071035 -0.2611048 -0.9201723

由reprex 包于 2020-06-02 创建(v0.3.0)

标签： rarraysdataframecrosstab

解决方案

我们可以使用pivot_widerwith column_to_rownamesfromtibble

library(dplyr)
library(tibble)
library(tidyr)
df %>% 
       pivot_wider(names_from = Meat, values_from = Price) %>%
       column_to_rownames('Bread') %>%
       as.matrix
#             Ham Roast Beef     Turkey    Pastrami
#White  0.3881185  0.2906277 -0.2855983  0.07601472
#Wheat -0.5602986  0.4471884  0.9085011 -0.50505960
#Rye   -0.3010040 -0.7260360 -1.1800770  0.25307471

或与acast

library(reshape2)
acast(df, Bread ~ Meat)

或xtabs从base R

out <- xtabs(Price ~ Bread + Meat, df)
names(dimnames(out)) <- c("Bread Type", "Meat Selection")
out
#          Meat Selection
#Bread Type         Ham    Pastrami  Roast Beef      Turkey
#     Rye   -0.30100401  0.25307471 -0.72603598 -1.18007703
#     Wheat -0.56029860 -0.50505960  0.44718837  0.90850113
#     White  0.38811847  0.07601472  0.29062767 -0.28559829

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