[問題] 用regex從檔名尾拿出數4-7位數字

看板R_Language作者luenchang (luen)時間3年前 (2021/10/10 10:09)推噓0(0推 0噓 5→)

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[問題敘述]: 請教先進們，我有21個檔案。我想從檔案名稱的尾巴拿出數字的部分，位數介於4到7位。檔案是pdf及docx. 我已先把不要的字串去除，直到尾巴部分留下數字，這部分命名為have. 21個檔案中只有第一個檔案的目標數字是7位(4614834)，第2到21個檔案都是4位。目前我的regex 拿出的數字全是4位數，不知道為何 \\d{4,7} 只從第1個檔案拿出4834，而不是4614834 。我把拿出的數字命名為 want [程式範例]: 請參考以下網頁第一個部分 Extract numbers of varying length from the end of strings https://hackmd.io/@Chang/string-manipulation-in-R 或以下的程式: 拿出檔名 file.names <- list.files( path=dir.assignment.2 ,pattern=".*\\.pdf$|.*\\.docx$" ,full.names=FALSE) # length(file.names) 21 拿出檔名尾數字 file.names.1 <- data.frame(file.name=file.names ,stringsAsFactors = F) %>% # Remove unwanted strings dplyr::mutate(have= stringr::str_remove_all( string=file.names ,pattern = "_Assign2_DMC-1.pdf|-1.docx|-1.pdf|_FINAL.pdf|-2.docx|.docx|.pdf") ,want=gsub(x=have, pattern = "(.*)(\\d{4,7})$", replacement = "\\2", perl = TRUE)) %>% #Keep wanted columns dplyr::select(have, want) 結果 # have want # 1 agarslawrence_204628_20026409_DMC_Assignment2_4614834 4834 # 2 andrewstimothy_297293_19936198_DMC Assignment 2 0953 0953 # 3 ashtonisabel_294366_19979255_DMC_2021S2_A2_6589 6589 # 4 beaumontjenna_294376_20033339_DMC_Assignment2_8752 8752 # 5 claytonphilipandrew_125548_20002099_DMC_Assignment2_7392 7392 # 6 eddydani_297300_19967943_DMC_Assignment2_4833 4833 # 7 edwardsfelicity_281039_19732901_DMC_Assignment2_4127 4127 # 8 gannonsean_294373_19967863_DMC_Assignment2_6490 6490 # 9 gawjames_295684_19988820_DMC_Assignment2_7389 7389 # 10 godwinsam_294371_20034982_DMC_Assignment2_unikey_6083 6083 # 11 guanqi_LATE_296467_20039218_ DMC_Assignment2_0313 0313 # 12 herbertrob_110692_19622280_DMC_Assignment2_2309 2309 # 13 hopkinsnathan_293664_20025212_DMC_Assignment2_8928 8928 # 14 huangannette_265602_20028154_DMC_Assignment 2_6822 6822 # 15 ilaovince_294377_20026222_DMC_Assignment2_6193 6193 # 16 lammichael_293038_19961008_DMC_assignment2_0718 0718 # 17 lamyanyin_294380_19991757_DMC_Assignment2_6098 6098 # 18 leekenneth_281025_19958430_DMC_Assignment2_8800 8800 # 19 luimatthew_296777_20032458_DMC_Assignment2_0384 0384 # 20 mcphailsandi_283784_20036309_5572 5572 # 21 millerjake_278059_20036475_DMC_Assignment2_8847 8847 -- ※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 49.197.45.209 (澳大利亞) ※ 文章網址: https://www.ptt.cc/bbs/R_Language/M.1633831748.A.F2E.html