r：由多个列组成计数 [英] r: group by multiple columns and count

问题描述

我有以下数据框， df ：

LeftOrRight SpeedCategory   NumThruLanes
R           25to45          3             
L           45to62          2           
R           Gt62            1           

我想通过SpeedCategory进行分组，并循环遍历其他列，以获取每个速度类别中每个唯一代码的频率，如下所示：

I want to group it by SpeedCategory and loop through the other columns to get the frequency of each unique code in each speed category-- something like this:

                 25to45 45to62 Gt62
LeftOrRight    L      0      1    0
               R      1      0    1
NumThruLanes   1      0      0    1
               2      0      1    0
               3      1      0    0

最近我能够来的是这样的：

The closest I have been able to come to is this:

for (col in df){
tbl <- table(col, df$SpeedCategory)
print(tbl)
}

其中打印出以下内容（第一个SpeedCategory，然后NumThruLanes）：

Which prints out the following (first SpeedCategory, then NumThruLanes):

col   25to45 45to62 Gt62
  L        0      1    0
  R        1      0    1

col   25to45 45to62 Gt62
  1        0      0    1
  2        0      1    0
  3        1      0    0

我很确定我可以用 aggregate（）或者可以从 dplyr的group_by完成我的目标，但我是R的新手，无法弄清楚语法。在 pandas 中，我将使用 MultiIndex ，但我不知道R等同物是什么，所以很难google。

I am pretty sure i can accomplish my goal with aggregate() or maybe group_by from dplyr, but I am new to R and can't figure out the syntax. In pandas I would use a MultiIndex but I don't know what the R equivalent is so it's difficult to google.

我想尝试在一次通过或循环中做所有事情，因为我有十几个列可以通过。

I'd like to try to do everything in one pass, or with a loop, since I have over a dozen columns to get through.

推荐答案

表包使得以非常具体的方式格式化表格变得容易。语法需要一些习惯，但是对于这个问题，它很简单：

The tables package makes it easy to format tables in very specific ways. The syntax takes some getting used to, but for this problem it's pretty straight-forward:

exd <- read.table(text = "LeftOrRight SpeedCategory   NumThruLanes
R           25to45          3             
L           45to62          2           
R           Gt62            1", header = TRUE)       

## to get counts by default we need everything to be categorical
exd$SpeedCategory <- factor(exd$SpeedCategory)

library(tables)
tabular(LeftOrRight + NumThruLanes ~ SpeedCategory, data = exd)

##                SpeedCategory            
##                25to45        45to62 Gt62
## LeftOrRight  L 0             1      0   
##              R 1             0      1   
## NumThruLanes 1 0             0      1   
##              2 0             1      0   
##              3 1             0      0

如果你有很多列可以迭代，你c一个程式化的公式，例如，

If you have a lot of columns to iterate over, you can construct the formula programatically, e.g.,

tabular(as.formula(paste(paste(names(exd)[-2], collapse = " + "),
                         names(exd)[2], sep = " ~ ")),
        data = exd)

作为奖金，有 html 和 latex ，可以轻松地将您的表格标记为包含在文章或报告中。

As a bonus there are html and latex methods, making it easy to mark your table up for inclusion in an article or report.

这篇关于r：由多个列组成计数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！