计算项目在多个列中的每一列中发生的次数

问题描述

我想阅读一个表，并创建另一个表，它可以计算多个特定列中唯一ID的次数。

I would like to read a table and create another table that counts how many times a unique ID occurs in multiple specific columns.

例如，我有一个表每一行显示交易，用户标识每个人的角色。

For example, I have a table where each row shows a transaction, with a userId identifying the role of each person.

buyer      <- c("A", "A", "B", "A", "B", "C")
seller     <- c("C", "B", "C", "B", "C", "A")
negotiator <- c("B", "C", "D", "D", "A", "B")

df <- data.frame(buyer, seller, negotiator)
df
#    buyer seller negotiator
#  1     A      C          B
#  2     A      B          C
#  3     B      C          D
#  4     A      B          D
#  5     B      C          A
#  6     C      A          B

然后我会喜欢创建一个表，可以计算userId在交易中的角色数量。

I would then like to create a table that counts how many times a userId fulfilled a role in the transactions.

#   id  asBuyer  asSeller  asNegotiator
#    A        3         1             1
#    B        2         2             2
#    C        1         3             1
#    D        0         0             2

需要创建不同的数据框然后合并？

Would I need to create different dataframes and then merge?

推荐答案

列表例如

dd<-reshape2::melt(df,0)
xtabs(~value+variable,dd)
#      variable
# value buyer seller negotiator
#     A     3      1          1
#     B     2      2          2
#     C     1      3          1
#     D     0      0          2

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