[英]How to permute a network in igraph for R?
我正在尝试为 R 中的 Monte Carlo 过程编写代码。我的目标是估计为 igraph 包格式化的加权、单分、无向网络计算的度量的重要性。
到目前为止,我在代码中包含了以下步骤:
nodes <- read.delim("nodes.txt")
links <- read.delim("links.txt")
anurosnet <- graph_from_data_frame(d=links, vertices=nodes, directed=F)
anurosnet
modularity1 = cluster_louvain(anurosnet)
modularity1$modularity #observed value
obs=modularity1$modularity
obs
real<-data.frame(obs)
real
Nperm = 9 #I am starting with a low n, but intend to use at least 1000 permutations
randomized.modularity=matrix(nrow=length(obs),ncol=Nperm+1)
row.names(randomized.modularity)=names(obs)
randomized.modularity[,1]=obs
randomized.modularity
i<-1
while(i<=Nperm){
randomnet <- rewire(anurosnet, with=each_edge(0.5)) #rewire vertices with constant probability
E(randomnet)$weight <- sample(E(anurosnet)$weight) #shuffle initial weights and assign them randomly to edges
mod<-(cluster_louvain(randomnet))
mod$modularity
linha = mod$modularity
randomized.modularity[,i+1]=linha
print(i)
i=i+1
}
randomized.modularity #Here the result is not as expected
niveis<-row.names(randomized.modularity)
for(k in niveis)
{
if(any(is.na(randomized.modularity[k,]) == TRUE))
{
print(c(k, "metrica tem NA"))
} else {
nome.arq<- paste("modularity",k,".png", sep="")
png(filename= nome.arq, res= 300, height= 15, width=21, unit="cm")
plot(density(randomized.modularity[k,]), main="Observed vs. randomized",)
abline(v=obs[k], col="red", lwd=2, xlab="")
dev.off()
print(k)
nome.arq<- paste("Patefield_Null_mean_sd_",k,".txt", sep="")
write.table(cbind(mean(randomized.modularity[k,]),sd(randomized.modularity[k,])), file=paste(nome.arq,sep=""),
sep=" ",row.names=TRUE,col.names=FALSE)
}
}
significance=matrix(nrow=nrow(randomized.modularity),ncol=3)
row.names(significance)=row.names(randomized.modularity)
colnames(significance)=c("p (rand <= obs)", "p (rand >= obs)", "p (rand=obs)")
signif.sup=function(x) sum(x>=x[1])/length(x)
signif.inf=function(x) sum(x<=x[1])/length(x)
signif.two=function(x) ifelse(min(x)*2>1,1,min(x)*2)
significance[,1]=apply(randomized.modularity,1,signif.inf)
significance[,2]=apply(randomized.modularity,1,signif.sup)
significance[,3]=apply(significance[,-3],1,signif.two)
significance
步骤 3 中出了点问题。我原以为向量会填充 10 个值,但由于某种原因,它会在一段时间后停止。
插槽“mod$modularity”突然收到 2 个值而不是 1 个。
代码开头提到的两个TXT文件可以从这里下载:
https://1drv.ms/t/s!AmcVKrxj94WClv8yQyqyl4IWk5mNvQ https://1drv.ms/t/s!AmcVKrxj94WClv8z_Pow5Tg2U7mjLw
请你帮助我好吗?
您的错误是由于与您的randomized.modularity
矩阵和一些随机模块化结果的维度不匹配。 在您的示例中,您的矩阵最终为[1 x Nperm]
但有时在排列过程中会返回 2 个模块化分数。 为了解决这个问题,我只是将结果存储在一个列表中。 由于模块化分数不匹配,因此需要调整其余分析。
library(igraph)
nodes <- read.delim("nodes.txt")
links <- read.delim("links.txt")
anurosnet <- graph_from_data_frame(d=links, vertices=nodes, directed=F)
anurosnet
modularity1 = cluster_louvain(anurosnet)
modularity1$modularity #observed value
obs <- modularity1$modularity
obs
real<-data.frame(obs)
real
Nperm = 100 #I am starting with a low n, but intend to use at least 1000 permutations
#randomized.modularity <- matrix(nrow=length(obs),ncol=Nperm+1)
#row.names(randomized.modularity) <- names(obs)
randomized.modularity <- list()
randomized.modularity[1] <- obs
randomized.modularity
for(i in 1:Nperm){
randomnet <- rewire(anurosnet, with=each_edge(0.5)) #rewire vertices with constant probability
E(randomnet)$weight <- sample(E(anurosnet)$weight) #shuffle initial weights and assign them randomly to edges
mod <- (cluster_louvain(randomnet))
mod$modularity
linha = mod$modularity
randomized.modularity <- c(randomized.modularity, list(linha))
}
randomized.modularity
randomized.modularity <- lapply(seq_len(Nperm), function(x){
randomnet <- rewire(anurosnet, with=each_edge(0.5)) #rewire vertices with constant probability
E(randomnet)$weight <- sample(E(anurosnet)$weight) #shuffle initial weights and assign them randomly to edges
return(cluster_louvain(randomnet)$modularity)
})
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