我需要根据两个标准创建几个矩阵：ideo和time。
这是我的代码的一部分，它不起作用。我看到使用列表对象存储新子集中的数字时遇到的问题，但我不知道在列表中同时列出i和j的方法。我应该list(list())吗？还有什么其他方法来编码这个问题？
ideo.list<-list(f1,f2,f3,f4,f5,f6,f7,f8,f9)
time.list<-list(t1,t2,t3,t4)
dattime.list<-list()
for (j in 1:length(time.list)){
for (i in 1:length(ideo.list)){
dat.sub<-subset(dat,iyear %in% time.list[[j]] & Ideo %in% ideo.list[[i]])
dattime.list[[i*j]]<-apply(dat.sub[,5:13],2,sum)
}}
nn<-matrix(unlist(dattime.list), byrow=TRUE, ncol=9,nrow=length(dattime.list) )
输入数据的头部如下：
iyear Ideo Armed.Assault Assassination
1 1982 Separatist / New Regime Nationalist / Ethnic Nationalist 0 0
2 1994 Separatist / New Regime Nationalist / Ethnic Nationalist 0 0
3 1995 Left Wing Terrorist Groups (Anarchist) 0 0
4 2010 Racist Terrorist Groups 1 0
5 2013 Left Wing Terrorist Groups (Anarchist) 0 0
6 2014 Cell Strategy and Terrorist Groups 0 0
Bombing.Explosion Facility.Infrastructure.Attack Hijacking Hostage.Taking..Barricade.Incident.
1 1 0 0 0
2 0 1 0 0
3 0 1 0 0
4 0 0 0 0
5 0 1 0 0
6 0 1 0 0
Hostage.Taking..Kidnapping. Unarmed.Assault Unknown
1 0 0 0
2 0 0 0
3 0 0 0
4 0 0 0
5 0 0 0
6 0 0 0
谢谢你的帮助！