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合併僅按特定列比較的兩個 CSV

tag-icon • tag-icon sed awk grep csv join
合併僅按特定列比較的兩個 CSV

我想比較兩個具有以下格式的 CSV 檔案。他們沒有標題。我想透過特定列（在本例中為第二列）對它們進行比較。

來源 CSV 檔案大約 4-5GB，因此無法將它們載入到記憶體中。

如果 old.csv 中沒有符合的列，則將每個新行寫入 out.csv 中。

第二列將是一個 html 鏈接，為了簡單起見，這裡只用一個字。

我的問題是否可以使用 sed、awk、join 或 grep 來獲得相同的結果？

舊的.csv

"person"|"john"|"smith"
"person"|"anne"|"frank"
"person"|"bob"|"macdonald"
"fruit"|"orange"|"banana"
"fruit"|"strawberry"|"fields"
"fruit"|"ringring"|"banana"

新的.csv

"person"|"john"|"smith"
"person"|"anne"|"frank"
"person"|"bob"|"macdonald"
"fruit"|"orange"|"banana"
"fruit"|"strawberry"|"fields"
"glider"|"person"|"airport"
"fruit"|"ringring"|"banana"
"glider"|"person2"|"airport"

差異.py

#!/usr/bin/env python3

"""
Source: https://gist.github.com/davidrleonard/4dbeebf749248a956e44
Usage: $ ./csv-difference.py -d new.csv -s old.csv -o out.csv -c 1
"""

import sys
import argparse
import csv

def main():
    parser = argparse.ArgumentParser(description='Output difference in CSVs.')
    parser.add_argument('-d', '--dataset', help='A CSV file of the full dataset', required=True)
    parser.add_argument('-s', '--subset', help='A CSV file that is a subset of the full dataset', required=True)
    parser.add_argument('-o', '--output', help='The CSV file we should write to (will be overwritten if it exists', required=True)
    parser.add_argument('-c', '--column', help='A number of the column to be compared (0 is column 1, 1 is column 2, etc.)', required=True, type=int)

    args = parser.parse_args()
    dataset_file = args.dataset
    subset_file = args.subset
    output_file = args.output
    column_num = args.column

    with open(dataset_file, 'r') as datafile, open(subset_file, 'r') as subsetfile, open(output_file, 'w') as outputfile:
        data = {row[column_num]: row for row in csv.reader(datafile, delimiter='|', quotechar='"')}
        subset = {row[column_num]: row for row in csv.reader(subsetfile, delimiter='|', quotechar='"')}

        data_keys = set(data.keys())
        subset_keys = set(subset.keys())
        output_keys = data_keys - subset_keys

        output = [data[key] for key in output_keys]
        output_csv = csv.writer(outputfile, delimiter='|', quotechar='"', quoting=csv.QUOTE_ALL)
        for row in output:
            output_csv.writerow(row)

if __name__ == '__main__':
    main()

sys.stdout.flush()

哪個正在生成out.csv

"glider"|"person"|"airport"
"glider"|"person2"|"airport"

答案1

使用 awk 超簡單：

$ awk -F'|' 'NR == FNR {old[$2]; next} !($2 in old)' old.csv new.csv
"glider"|"person"|"airport"
"glider"|"person2"|"airport"

它將 old.csv 檔案的第二個欄位儲存在名為「old」的陣列中，然後對於 new.csv 文件，它將列印第二個欄位不在「old」陣列中的記錄。

確實，這不會尊重引號內的任何管道字元。為此，我喜歡 ruby​​ 的 csv 模組：

ruby -rcsv  -e '
  old_col2 = []
  old_data = CSV.foreach("./old.csv", :col_sep => "|") do |row|
    old_col2 << row[1]
  end

  CSV.foreach("./new.csv", :col_sep => "|") do |row|
    if not old_col2.include?(row[1])
      puts CSV.generate_line(row, :col_sep => "|", :force_quotes => true)
    end
  end
'

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