作者luenchang (luen)
看板R_Language
標題 [問題] 用regex提取2到3位的數字
時間Mon Dec 21 12:17:10 2020
各位先進，
我想從字串中提取出數字的部分。我的字串有規律性，結構上，開頭是2到3位的數字，空白
，接著不等位數的字母，或字母和數字。我想提取的是開頭的部分。我試了兩個方法，方法
1只拿出數字的最末位，方法2拿出完整的數字。我不知道方法1的regex寫法有什麼錯。
以下是我的字串及code
# Strings to extract
strings <- c("130 UDINE", "162 BF02", "163 AS04", "164 AL08", "165 BR12", "166 S
A13", "167 MA14", "167 MA14", "168 OC15", "85 BERGAMO")
# Method 1 to extract the beginning part of the strings (not working)
gsub(pattern = "^(\\d){2,3}(\\s).*", replacement = "\\1", x=strings)
# [1] "0" "2" "3" "4" "5" "6" "7" "7" "8" "5"
# Method 2 to extract the beginning part of the strings (not working)
gsub(pattern = "^(\\d+)(\\s).*", replacement = "\\1", x=strings)
# [1] "130" "162" "163" "164" "165" "166" "167" "167" "168" "85"
謝謝
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1F：推 celestialgod: library(stringr); str_extract_all(strings, ”\\d 12/21 13:11
2F：→ celestialgod: {2,3}”) 12/21 13:11
3F：→ andrew43: 用tstrsplit很直覺 12/21 13:23
4F：→ andrew43: data.table::tstrsplit(strings, " ", keep = 1)[[1]] 12/21 13:24
5F：→ resentis: 大概是\\d的數量範圍要跟緊\\d 12/21 20:30
6F：→ resentis: "^(\\d{2,3})(\\s).*" 12/21 20:30
7F：推 JuanMaestrow: str_extract(string, regex(“^\\d+”)) 就可以囉 12/21 21:45