如何生成 R 计数矩阵 [英] How to produce an R count matrix

问题描述

在 R 中，我可以使用我感兴趣的特定列名作为数组返回计数结果，如下所示.

In R, I can return the count results using the specific column names I am interested in as an array as below.

require("plyr")
bevs <- data.frame(cbind(name = c("Bill", "Llib"), drink = c("coffee", "tea", "cocoa", "water"), cost = seq(1:8)))
count(bevs, c("name", "drink"))

# produces
  name  drink freq
1 Bill  cocoa    2
2 Bill coffee    2
3 Llib    tea    2
4 Llib  water    2

如何获得矩阵中两个特定列名称的计数结果，该矩阵具有列:所有独特的饮料，行:所有独特的名称和单元格:频率(如下所示)?

How can I get the count result of two specific column names in a matrix which has columns: all unique drinks, rows: all unique names and cells: freqs (like below)?

     cocoa  coffee tea water
Bill   2      2     0   0
Llib   0      0     2   2

P.S:显然，解决方案不需要使用plyr.

P.S: Obviously, the solution does not need to use plyr.

推荐答案

您需要一个列联表，可以使用 table 创建:

You want a contingency table, which you can create using table:

table(bevs[, c("name", "drink")])
#      drink
#name   cocoa coffee tea water
#  Bill     2      2   0     0
#  Llib     0      0   2     2

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