address <- c("대전광역시 서구 탄방동 홈플러스","대전광역시 동구 효동 주민센터","대전광역시 대덕구 오정동 한남마트","대전광역시 동구 자양동 87-3번지 성동경로당","대전광역시 유성구 용계로 128")
## matches <- regmatches(address, gregexpr("\\b\\w*동\\b", address, perl=TRUE ))
matches <- regmatches(address, gregexpr("\\b\\w*동\\b", address ))
dong <- unlist(lapply(matches, function(x) if (length(x) == 0) NA else x))
data <- data.frame(address,dong, stringsAsFactors = FALSE)
data
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