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如何拆分 CSV 中的欄位並將該行中的欄位複製到新行

tag-icon • tag-icon awk sed csv text-formatting
如何拆分 CSV 中的欄位並將該行中的欄位複製到新行

我有一個使用 CSV 文件的目標，第 6 個字段包含單詞，但最大字符長度為 16。

目前文件

"5","4","3","2","1","XYZ ABCD E"
"1","2","3","4","5","AB CDE F GHI JK LMNOP Q RS TUV W XYZ 12 3456 7890"
"9","8","7","6","5","LMN O PQ R"

所需輸出

"5","4","3","2","1","XYZ ABCD E"
"1","2","3","4","5","AB CDE F GHI JK"
"1","2","3","4","5","LMNOP Q RS TUV W"
"1","2","3","4","5","XYZ 12 3456 7890"
"9","8","7","6","5","LMN O PQ R"

答案1

使用GNU Awk ( gawk) 運行fold取得行/變數/協進程

gawk -F, '
  BEGIN{
    OFS=FS; 
    cmd="fold -sw 16";
  }

  # if total length (16 + 2 for quotes) is within limit, print as-is
  length($NF) <= 18 {print; next}

  # else
  {
    # trim the quotes, then fold
    print substr($NF,2,length($NF)-2) |& cmd; 
    close(cmd,"to"); 
    NF--; 
    while((cmd |& getline var) > 0){

      # (optional) trim trailing whitespace
      sub(/[ \t]+$/,"",var);

      print $0, "\"" var "\"" ;
    }
    close(cmd,"from");
  }
' file.csv

從操作中刪除sub尾隨空格fold。

請注意，要獲得顯示的精確輸出，需要fold -sw17在 16 個字元處加上（隨後刪除的）尾隨空格進行換行。但是，這樣做可能會導致折疊輸出的最後一行超過 16 個字元的限制。

答案2

我創建了一個相當蹩腳的 awk 腳本，它保留了雙引號。它來了：

{
    for ( i=0; i<= length($6); i+=16 )
    {
        if ( i+17 < length($6) )
        {
            if ( i == 0 )
                printf ("%s,%s,%s,%s,%s,%s\"\n", $1, $2, $3, $4, $5, substr($6,i,16))
            else
                printf ("%s,%s,%s,%s,%s,\"%s\"\n", $1, $2, $3, $4, $5, substr($6,i+1,16))
        }
        else
        {
            if ( i == 0 )
                printf ("%s,%s,%s,%s,%s,%s\n", $1, $2, $3, $4, $5, substr($6,i,16))
            else
                printf ("%s,%s,%s,%s,%s,\"%s\n", $1, $2, $3, $4, $5, substr($6,i+1,16))
        }
    }
}

輸出是：

$ awk -F, -f awks csvfields
"5","4","3","2","1","XYZ ABCD E"
"1","2","3","4","5","AB CDE F GHI JK"
"1","2","3","4","5"," LMNOP Q RS TUV "
"1","2","3","4","5","W XYZ 12 3456 78"
"1","2","3","4","5","90"
"9","8","7","6","5","LMN O PQ R"
$

唯一的問題是，如果邊界處有空格，它會被保留，與已刪除的範例不同。

答案3

嘗試使用下面的程式碼，效果也很好

 k=16;for ((j=1;j<=50;j++)); do  awk -v j="$j" -v k="$k" -F "," '{if(length($NF) > 16){print $1,$2,$3,$4,$5,substr($NF,j,k)}else {print $0}}' filename; j=$(($j+16)); done|sort | uniq

輸出

"5","4","3","2","1","XYZ ABCD E"
"1","2","3","4","5","AB CDE F GHI JK"
"1","2","3","4","5","LMNOP Q RS TUV W"
"1","2","3","4","5","XYZ 12 3456 7890"
"9","8","7","6","5","LMN O PQ R"

答案4

僅 SHELL 方法（在 Bash 和 Ksh93 上測試）。不過，我確實喜歡這種fold方法，因為它使用現有的工具。

# read from stdin, output to stdout
# Note no Shebang line at top so it made it easier for to try bash/ksh as interpreters

OIFS="$IFS"
IFS=,
while read f1 f2 f3 f4 f5 f6; do
    f6=${f6#\"}
    f6=${f6%\"}             # strip DQs
    if ((${#f6}<17)); then  # no action
            IFS="$OIFS"
            echo "$f1,$f2,$f3,$f4,$f5,\"$f6\""
            IFS=","
            continue
    else
            IFS="$OIFS"
            while ((${#f6}>17)); do
                    n6=${f6:0:16}
                    f6=${f6#$n6}
                    n6=${n6# }
                    n6=${n6% }
                    echo "$f1,$f2,$f3,$f4,$f5,\"$n6\""
            done
            echo "$f1,$f2,$f3,$f4,$f5,\"${f6# }\""
    fi
    IFS=","
done
IFS="$OIFS"
exit

結果：

"5","4","3","2","1","XYZ ABCD E"
"1","2","3","4","5","AB CDE F GHI JK"
"1","2","3","4","5","LMNOP Q RS TUV W"
"1","2","3","4","5","XYZ 12 3456 7890"
"9","8","7","6","5","LMN O PQ R"

若要在不使用 using 或類似的情況下解決分詞問題fold，以下程式碼應取代上面顯示的註解掉的行。也將第二個echo命令列替換為：

                    c6="$f6"
                    n6=""
                    while (((${#n6}+${#nw})<=16)); do
                            n6=$n6${c6%% *}\
                            n6=${n6# }
                            eval c6=\${c6\#${c6%% *} }
                            nw=${c6%% *}
                    done
                    #n6=${f6:0:16} ### replace by above

並替換

            echo "$f1,$f2,$f3,$f4,$f5,\"${f6# }\""

和

            ((${#f6}>0)) && echo "$f1,$f2,$f3,$f4,$f5,\"${f6# }\""

以避免出現任何空白欄位 6 餘數。

使用以下測試檔案：

"5","4","3","2","1","XYZ ABCD E"
"1","2","3","4","5","AB CDE F GHI JK LMNOP Q RS TUV W XYZ 12 3456 7890"
"9","8","7","6","5","LMN O PQ R"
"1","2","3","4","5","A BB CCC DDD EEEE FFFFF GGGGGG HHHHHHH"

結果：

"5","4","3","2","1","XYZ ABCD E"
"1","2","3","4","5","AB CDE F GHI JK"
"1","2","3","4","5","LMNOP Q RS TUV W"
"1","2","3","4","5","XYZ 12 3456 7890"
"9","8","7","6","5","LMN O PQ R"
"1","2","3","4","5","A BB CCC DDD"
"1","2","3","4","5","EEEE FFFFF"
"1","2","3","4","5","GGGGGG HHHHHHH"

然而，現有工具的使用fold要容易得多，並且遵循 UNIX 哲學——構建在現有的簡單工具之上。但如果您喜歡 Shell 編程，那麼上述是獲得解決方案的一種方法。如果有人需要代碼的解釋，請與我聯絡。

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