Re: [問題] 比對兩個list

[CKPILOT (新年快樂!)]

#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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※ 編輯: CKPILOT (123.193.135.208), 11/06/2015 14:22:23
→ celestialgod: 建議：append一個NULL的list並非好習慣...
→ celestialgod: 還是先preallocate: result=vector('list', length(
→ celestialgod: intersection))
→ celestialgod: #1LjDrSmd (R_Language)
→ CKPILOT: Thanks, it's really important for mem allocation
※ 編輯: CKPILOT (123.193.135.208), 11/06/2015 15:19:20
※ 編輯: CKPILOT (123.193.135.208), 11/06/2015 15:20:28