作者CKPILOT (新年快乐!)
看板R_Language
标题Re: [问题] 比对两个list
时间Fri Nov 6 14:21:01 2015
#BAD example: without memory preallocation
intersection <- names(a.list)[names(a.list) %in% names(b.list)]
result <- as.list(NULL)
for(i in intersection){
result[[i]] <- sum(table(a.list[[i]][a.list[[i]] %in% b.list[[i]]]))
}
#Fixed:
intersection <- names(a.list)[names(a.list) %in% names(b.list)]
result <- vector("list", length(intersection))
names(result) <- intersection
for(i in intersection){
result[[i]] <- sum(table(a.list[[i]][a.list[[i]] %in% b.list[[i]]]))
#cat(tracemem(result), '\n')
}
--
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※ 编辑: CKPILOT (123.193.135.208), 11/06/2015 14:22:23
1F：→ celestialgod: 建议：append一个NULL的list并非好习惯... 11/06 14:25
2F：→ celestialgod: 还是先preallocate: result=vector('list', length( 11/06 14:25
3F：→ celestialgod: intersection)) 11/06 14:25
5F：→ CKPILOT: Thanks, it's really important for mem allocation 11/06 14:31
※ 编辑: CKPILOT (123.193.135.208), 11/06/2015 15:19:20
※ 编辑: CKPILOT (123.193.135.208), 11/06/2015 15:20:28