用R创建关系矩阵

Question

我的数据包括参与项目的不同个人的项目，以及项目实施的年份。

如何为每年创建一个nxn关系矩阵(n是个体的数量)来统计个人之间的协作数。

考虑以下再现所需结构的示例：

# Example dataframe
set.seed(1)
tp=cbind(paste(rep("project",10),1:10,sep=""),sample(2005:2010,10,replace=T))
tp=tp[sample(1:10,50,T),]
id=sample(paste(rep("id",10),1:10,sep=""),50,T)
df=as.data.frame(cbind(tp,id));rm(tp,id)
names(df)=c("project","year","id")
df=df[order(df$project,df$id),]

df[1:10,]
# project  year id
# project1 2006 id1
# project1 2006 id3
# project1 2006 id5
# project1 2006 id5
# project4 2006 id3
# project4 2006 id4
# project5 2006 id3
# project5 2006 id4
# project6 2008 id2
# project6 2008 id3

例如，2006年的关系矩阵如下所示

    id1 id2 id3 id4 id5
id1  0   0   1   0   1
id2  0   0   0   0   0
id3  1   0   0   2   1
id4  0   0   2   0   0
id5  1   0   1   0   0

# link between 1 and 3, 1 and 5, 3 and 5 on project 1
# links between 3 and 4 on project 4 and project 5
# the matrix is symmetric
# the diagonal is O because an individual cannot collaborate with himself

Answer 1

您还可以将dplyr与tidyr一起用于以下内容：

library(dplyr)
library(tidyr)

df %>%
  unique %>%
  mutate(val = 1) %>%
  spread(id, val) %>%
  select(-project) %>%
  group_by(year) %>%
  do({
    mat <- select(., -year) %>% as.matrix
    mat[is.na(mat)] <- 0
    cp <- crossprod(mat)
    diag(cp) <- 0
    cp %>% as.data.frame %>%
      add_rownames(var = 'id')
  }) %>%
  ungroup