计算R中的一组变量中的值的出现次数（每行） [英] Count occurrences of value in a set of variables in R (per row)

问题描述

假设我有一个包含10个数字变量V1-V10（列）和多行（个案）的数据框。

Let's say I have a data frame with 10 numeric variables V1-V10 (columns) and multiple rows (cases).

我想R ：对于每种情况，给出一组变量中某个值出现的次数。

What I would like R to do is: For each case, give me the number of occurrences of a certain value in a set of variables.

例如，在该单个数值中出现的数字99 V2，V3，V6的行，其显然具有最小值0（三个都不具有值99）和最大值3（所有三个具有值99）。

For example the number of occurrences of the numeric value 99 in that single row for V2, V3, V6, which obviously has a minimum of 0 (none of the three have the value 99) and a maximum of 3 (all of the three have the value 99).

我真的在寻找一个等效于 SPSS函数 COUNT ：COUNT 创建一个数字变量，

I am really looking for an equivalent to the SPSS function COUNT: "COUNT creates a numeric variable that, for each case, counts the occurrences of the same value (or list of values) across a list of variables."

我考虑过表格（）和库plyr的 count（），但我真的不能弄清楚。矢量化计算偏好。非常感谢！

I thought about table() and library plyr's count(), but I cannot really figure it out. Vectorized computation preferred. Thanks a lot!

推荐答案

尝试

apply(df,MARGIN=1,table)

df 是您的 data.frame 。这将返回与data.frame中的行数相同长度的列表。列表的每个项目对应于data.frame的一行（以相同的顺序），并且它是一个表，其中内容是出现的次数，并且名称是对应的值。

Where df is your data.frame. This will return a list of the same length of the amount of rows in your data.frame. Each item of the list corresponds to a row of the data.frame (in the same order), and it is a table where the content is the number of occurrences and the names are the corresponding values.

例如：

df=data.frame(V1=c(10,20,10,20),V2=c(20,30,20,30),V3=c(20,10,20,10))
#create a data.frame containing some data
df #show the data.frame
  V1 V2 V3
1 10 20 20
2 20 30 10
3 10 20 20
4 20 30 10
apply(df,MARGIN=1,table) #apply the function table on each row (MARGIN=1)
[[1]]

10 20 
 1  2 

[[2]]

10 20 30 
 1  1  1 

[[3]]

10 20 
 1  2 

[[4]]

10 20 30 
 1  1  1 

#desired result

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