Dấu tách trường trong Python

Tệp CSV đến từ đâu?

Các tệp CSV thường được tạo bởi các chương trình xử lý lượng lớn dữ liệu. Chúng là một cách thuận tiện để xuất dữ liệu từ bảng tính và cơ sở dữ liệu cũng như nhập hoặc sử dụng dữ liệu đó trong các chương trình khác. Ví dụ: bạn có thể xuất kết quả của chương trình khai thác dữ liệu sang tệp CSV rồi nhập tệp đó vào bảng tính để phân tích dữ liệu, tạo biểu đồ cho bản trình bày hoặc chuẩn bị báo cáo để xuất bản

Các tệp CSV rất dễ làm việc theo chương trình. Bất kỳ ngôn ngữ nào hỗ trợ nhập tệp văn bản và thao tác chuỗi [như Python] đều có thể hoạt động trực tiếp với tệp CSV

Đọc tệp CSV với

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']

7

Việc đọc từ tệp CSV được thực hiện bằng cách sử dụng đối tượng

Column names are name, department, birthday month
    John Smith works in the Accounting department, and was born in November.
    Erica Meyers works in the IT department, and was born in March.
Processed 3 lines.

Column names are name, department, birthday month
    John Smith works in the Accounting department, and was born in November.
    Erica Meyers works in the IT department, and was born in March.
Processed 3 lines.

Column names are name, department, birthday month
    John Smith works in the Accounting department, and was born in November.
    Erica Meyers works in the IT department, and was born in March.
Processed 3 lines.

Đây là tệp

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

Đây là mã để đọc nó

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']

Điều này dẫn đến đầu ra sau

Column names are name, department, birthday month
    John Smith works in the Accounting department, and was born in November.
    Erica Meyers works in the IT department, and was born in March.
Processed 3 lines.

Mỗi hàng được trả về bởi

Column names are name, department, birthday month
    John Smith works in the Accounting department, and was born in November.
    Erica Meyers works in the IT department, and was born in March.
Processed 3 lines.

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

Đọc tệp CSV vào từ điển với

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']

7

Thay vì xử lý danh sách các phần tử

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

Một lần nữa, tệp đầu vào của chúng tôi,

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

Đây là mã để đọc nó như một cuốn từ điển lần này

import csv

with open['employee_birthday.txt', mode='r'] as csv_file:
    csv_reader = csv.DictReader[csv_file]
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        print[f'\t{row["name"]} works in the {row["department"]} department, and was born in {row["birthday month"]}.']
        line_count += 1
    print[f'Processed {line_count} lines.']

Điều này dẫn đến đầu ra giống như trước đây

Column names are name, department, birthday month
    John Smith works in the Accounting department, and was born in November.
    Erica Meyers works in the IT department, and was born in March.
Processed 3 lines.

Các khóa từ điển đến từ đâu? . Nếu bạn không có những thứ này trong tệp CSV của mình, bạn nên chỉ định các khóa của riêng mình bằng cách đặt tham số tùy chọn

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

Tham số Python CSV

Column names are name, department, birthday month
    John Smith works in the Accounting department, and was born in November.
    Erica Meyers works in the IT department, and was born in March.
Processed 3 lines.

7 tùy chọn

Đối tượng

Column names are name, department, birthday month
    John Smith works in the Accounting department, and was born in November.
    Erica Meyers works in the IT department, and was born in March.
Processed 3 lines.

• name,department,birthday month
  John Smith,Accounting,November
  Erica Meyers,IT,March
  

  9 chỉ định ký tự được sử dụng để phân tách từng trường. Mặc định là dấu phẩy [

  import csv
  
  with open['employee_birthday.txt', mode='r'] as csv_file:
      csv_reader = csv.DictReader[csv_file]
      line_count = 0
      for row in csv_reader:
          if line_count == 0:
              print[f'Column names are {", ".join[row]}']
              line_count += 1
          print[f'\t{row["name"]} works in the {row["department"]} department, and was born in {row["birthday month"]}.']
          line_count += 1
      print[f'Processed {line_count} lines.']
  

  0]

• import csv
  
  with open['employee_birthday.txt', mode='r'] as csv_file:
      csv_reader = csv.DictReader[csv_file]
      line_count = 0
      for row in csv_reader:
          if line_count == 0:
              print[f'Column names are {", ".join[row]}']
              line_count += 1
          print[f'\t{row["name"]} works in the {row["department"]} department, and was born in {row["birthday month"]}.']
          line_count += 1
      print[f'Processed {line_count} lines.']
  

  1 chỉ định ký tự được sử dụng để bao quanh các trường có chứa ký tự phân cách. Mặc định là trích dẫn kép [

  import csv
  
  with open['employee_birthday.txt', mode='r'] as csv_file:
      csv_reader = csv.DictReader[csv_file]
      line_count = 0
      for row in csv_reader:
          if line_count == 0:
              print[f'Column names are {", ".join[row]}']
              line_count += 1
          print[f'\t{row["name"]} works in the {row["department"]} department, and was born in {row["birthday month"]}.']
          line_count += 1
      print[f'Processed {line_count} lines.']
  

  2]

• import csv
  
  with open['employee_birthday.txt', mode='r'] as csv_file:
      csv_reader = csv.DictReader[csv_file]
      line_count = 0
      for row in csv_reader:
          if line_count == 0:
              print[f'Column names are {", ".join[row]}']
              line_count += 1
          print[f'\t{row["name"]} works in the {row["department"]} department, and was born in {row["birthday month"]}.']
          line_count += 1
      print[f'Processed {line_count} lines.']
  

  3 chỉ định ký tự được sử dụng để thoát ký tự dấu phân cách, trong trường hợp dấu ngoặc kép không được sử dụng. Mặc định là không có ký tự thoát

Các thông số này xứng đáng được giải thích thêm. Giả sử bạn đang làm việc với tệp

import csv

with open['employee_birthday.txt', mode='r'] as csv_file:
    csv_reader = csv.DictReader[csv_file]
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        print[f'\t{row["name"]} works in the {row["department"]} department, and was born in {row["birthday month"]}.']
        line_count += 1
    print[f'Processed {line_count} lines.']

name,address,date joined
john smith,1132 Anywhere Lane Hoboken NJ, 07030,Jan 4
erica meyers,1234 Smith Lane Hoboken NJ, 07030,March 2

Tệp CSV này chứa ba trường.

import csv

with open['employee_birthday.txt', mode='r'] as csv_file:
    csv_reader = csv.DictReader[csv_file]
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        print[f'\t{row["name"]} works in the {row["department"]} department, and was born in {row["birthday month"]}.']
        line_count += 1
    print[f'Processed {line_count} lines.']

import csv

with open['employee_birthday.txt', mode='r'] as csv_file:
    csv_reader = csv.DictReader[csv_file]
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        print[f'\t{row["name"]} works in the {row["department"]} department, and was born in {row["birthday month"]}.']
        line_count += 1
    print[f'Processed {line_count} lines.']

import csv

with open['employee_birthday.txt', mode='r'] as csv_file:
    csv_reader = csv.DictReader[csv_file]
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        print[f'\t{row["name"]} works in the {row["department"]} department, and was born in {row["birthday month"]}.']
        line_count += 1
    print[f'Processed {line_count} lines.']

import csv

with open['employee_birthday.txt', mode='r'] as csv_file:
    csv_reader = csv.DictReader[csv_file]
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        print[f'\t{row["name"]} works in the {row["department"]} department, and was born in {row["birthday month"]}.']
        line_count += 1
    print[f'Processed {line_count} lines.']

Có ba cách khác nhau để xử lý tình huống này

• Sử dụng một dấu phân cách khác
  Bằng cách đó, dấu phẩy có thể được sử dụng một cách an toàn trong chính dữ liệu. Bạn sử dụng tham số tùy chọn

  name,department,birthday month
  John Smith,Accounting,November
  Erica Meyers,IT,March
  

  9 để chỉ định dấu phân cách mới

• Gói dữ liệu trong dấu ngoặc kép
  Bản chất đặc biệt của dấu phân cách bạn đã chọn bị bỏ qua trong các chuỗi được trích dẫn. Do đó, bạn có thể chỉ định ký tự được sử dụng để trích dẫn với tham số tùy chọn

  import csv
  
  with open['employee_birthday.txt', mode='r'] as csv_file:
      csv_reader = csv.DictReader[csv_file]
      line_count = 0
      for row in csv_reader:
          if line_count == 0:
              print[f'Column names are {", ".join[row]}']
              line_count += 1
          print[f'\t{row["name"]} works in the {row["department"]} department, and was born in {row["birthday month"]}.']
          line_count += 1
      print[f'Processed {line_count} lines.']
  

  1. Miễn là ký tự đó cũng không xuất hiện trong dữ liệu, bạn vẫn ổn

• Thoát các ký tự phân cách trong dữ liệu
  Các ký tự thoát hoạt động giống như trong các chuỗi định dạng, vô hiệu hóa việc giải thích ký tự được thoát [trong trường hợp này là dấu phân cách]. Nếu một ký tự thoát được sử dụng, nó phải được chỉ định bằng tham số tùy chọn

  import csv
  
  with open['employee_birthday.txt', mode='r'] as csv_file:
      csv_reader = csv.DictReader[csv_file]
      line_count = 0
      for row in csv_reader:
          if line_count == 0:
              print[f'Column names are {", ".join[row]}']
              line_count += 1
          print[f'\t{row["name"]} works in the {row["department"]} department, and was born in {row["birthday month"]}.']
          line_count += 1
      print[f'Processed {line_count} lines.']
  

  3

Viết tệp CSV bằng

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']

7

Bạn cũng có thể ghi vào tệp CSV bằng cách sử dụng đối tượng

Column names are name, department, birthday month
    John Smith works in the Accounting department, and was born in November.
    Erica Meyers works in the IT department, and was born in March.
Processed 3 lines.

Column names are name, department, birthday month
    John Smith works in the Accounting department, and was born in November.
    Erica Meyers works in the IT department, and was born in March.
Processed 3 lines.

import csv

with open['employee_file.csv', mode='w'] as employee_file:
    employee_writer = csv.writer[employee_file, delimiter=',', quotechar='"', quoting=csv.QUOTE_MINIMAL]

    employee_writer.writerow[['John Smith', 'Accounting', 'November']]
    employee_writer.writerow[['Erica Meyers', 'IT', 'March']]

Tham số tùy chọn

import csv

with open['employee_birthday.txt', mode='r'] as csv_file:
    csv_reader = csv.DictReader[csv_file]
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        print[f'\t{row["name"]} works in the {row["department"]} department, and was born in {row["birthday month"]}.']
        line_count += 1
    print[f'Processed {line_count} lines.']

Column names are name, department, birthday month
    John Smith works in the Accounting department, and was born in November.
    Erica Meyers works in the IT department, and was born in March.
Processed 3 lines.

Column names are name, department, birthday month
    John Smith works in the Accounting department, and was born in November.
    Erica Meyers works in the IT department, and was born in March.
Processed 3 lines.

• Nếu

  Column names are name, department, birthday month
      John Smith works in the Accounting department, and was born in November.
      Erica Meyers works in the IT department, and was born in March.
  Processed 3 lines.
  

  7 được đặt thành

  Column names are name, department, birthday month
      John Smith works in the Accounting department, and was born in November.
      Erica Meyers works in the IT department, and was born in March.
  Processed 3 lines.
  

  9, thì

  name,address,date joined
  john smith,1132 Anywhere Lane Hoboken NJ, 07030,Jan 4
  erica meyers,1234 Smith Lane Hoboken NJ, 07030,March 2
  

  0 sẽ chỉ trích dẫn các trường nếu chúng chứa

  name,department,birthday month
  John Smith,Accounting,November
  Erica Meyers,IT,March
  

  9 hoặc

  import csv
  
  with open['employee_birthday.txt', mode='r'] as csv_file:
      csv_reader = csv.DictReader[csv_file]
      line_count = 0
      for row in csv_reader:
          if line_count == 0:
              print[f'Column names are {", ".join[row]}']
              line_count += 1
          print[f'\t{row["name"]} works in the {row["department"]} department, and was born in {row["birthday month"]}.']
          line_count += 1
      print[f'Processed {line_count} lines.']
  

  1. Đây là trường hợp mặc định
• Nếu

  Column names are name, department, birthday month
      John Smith works in the Accounting department, and was born in November.
      Erica Meyers works in the IT department, and was born in March.
  Processed 3 lines.
  

  7 được đặt thành

  name,address,date joined
  john smith,1132 Anywhere Lane Hoboken NJ, 07030,Jan 4
  erica meyers,1234 Smith Lane Hoboken NJ, 07030,March 2
  

  4, thì

  name,address,date joined
  john smith,1132 Anywhere Lane Hoboken NJ, 07030,Jan 4
  erica meyers,1234 Smith Lane Hoboken NJ, 07030,March 2
  

  0 sẽ trích dẫn tất cả các trường
• Nếu

  Column names are name, department, birthday month
      John Smith works in the Accounting department, and was born in November.
      Erica Meyers works in the IT department, and was born in March.
  Processed 3 lines.
  

  7 được đặt thành

  name,address,date joined
  john smith,1132 Anywhere Lane Hoboken NJ, 07030,Jan 4
  erica meyers,1234 Smith Lane Hoboken NJ, 07030,March 2
  

  7, thì

  name,address,date joined
  john smith,1132 Anywhere Lane Hoboken NJ, 07030,Jan 4
  erica meyers,1234 Smith Lane Hoboken NJ, 07030,March 2
  

  0 sẽ trích dẫn tất cả các trường chứa dữ liệu văn bản và chuyển đổi tất cả các trường số thành loại dữ liệu

  name,address,date joined
  john smith,1132 Anywhere Lane Hoboken NJ, 07030,Jan 4
  erica meyers,1234 Smith Lane Hoboken NJ, 07030,March 2
  

  9
• Nếu

  Column names are name, department, birthday month
      John Smith works in the Accounting department, and was born in November.
      Erica Meyers works in the IT department, and was born in March.
  Processed 3 lines.
  

  7 được đặt thành

  import csv
  
  with open['employee_file.csv', mode='w'] as employee_file:
      employee_writer = csv.writer[employee_file, delimiter=',', quotechar='"', quoting=csv.QUOTE_MINIMAL]
  
      employee_writer.writerow[['John Smith', 'Accounting', 'November']]
      employee_writer.writerow[['Erica Meyers', 'IT', 'March']]
  

  1, thì

  name,address,date joined
  john smith,1132 Anywhere Lane Hoboken NJ, 07030,Jan 4
  erica meyers,1234 Smith Lane Hoboken NJ, 07030,March 2
  

  0 sẽ thoát khỏi dấu phân cách thay vì trích dẫn chúng. Trong trường hợp này, bạn cũng phải cung cấp giá trị cho tham số tùy chọn

  import csv
  
  with open['employee_birthday.txt', mode='r'] as csv_file:
      csv_reader = csv.DictReader[csv_file]
      line_count = 0
      for row in csv_reader:
          if line_count == 0:
              print[f'Column names are {", ".join[row]}']
              line_count += 1
          print[f'\t{row["name"]} works in the {row["department"]} department, and was born in {row["birthday month"]}.']
          line_count += 1
      print[f'Processed {line_count} lines.']
  

  3

Đọc lại tệp ở dạng văn bản thuần túy cho thấy tệp được tạo như sau

John Smith,Accounting,November
Erica Meyers,IT,March

Viết tệp CSV từ một từ điển với

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']

7

Vì bạn có thể đọc dữ liệu của chúng tôi trong từ điển, nên thật công bằng khi bạn cũng có thể viết nó ra từ từ điển

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

Không giống như

import csv

with open['employee_file.csv', mode='w'] as employee_file:
    employee_writer = csv.writer[employee_file, delimiter=',', quotechar='"', quoting=csv.QUOTE_MINIMAL]

    employee_writer.writerow[['John Smith', 'Accounting', 'November']]
    employee_writer.writerow[['Erica Meyers', 'IT', 'March']]

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

import csv

with open['employee_file.csv', mode='w'] as employee_file:
    employee_writer = csv.writer[employee_file, delimiter=',', quotechar='"', quoting=csv.QUOTE_MINIMAL]

    employee_writer.writerow[['John Smith', 'Accounting', 'November']]
    employee_writer.writerow[['Erica Meyers', 'IT', 'March']]

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

Đoạn mã trên tạo ra tệp đầu ra sau

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

Đọc tệp CSV với

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']

8

Để thể hiện một số sức mạnh của khả năng CSV của

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

Đọc CSV thành

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

Đó là nó. ba dòng mã và chỉ một trong số chúng đang thực hiện công việc thực tế.

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

Sau đây là một số điểm đáng lưu ý

• Đầu tiên,

  import csv
  
  with open['employee_birthday.txt'] as csv_file:
      csv_reader = csv.reader[csv_file, delimiter=',']
      line_count = 0
      for row in csv_reader:
          if line_count == 0:
              print[f'Column names are {", ".join[row]}']
              line_count += 1
          else:
              print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
              line_count += 1
      print[f'Processed {line_count} lines.']
  

  8 nhận ra rằng dòng đầu tiên của CSV chứa tên cột và tự động sử dụng chúng. Tôi gọi đây là Thiện
• Tuy nhiên,

  import csv
  
  with open['employee_birthday.txt'] as csv_file:
      csv_reader = csv.reader[csv_file, delimiter=',']
      line_count = 0
      for row in csv_reader:
          if line_count == 0:
              print[f'Column names are {", ".join[row]}']
              line_count += 1
          else:
              print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
              line_count += 1
      print[f'Processed {line_count} lines.']
  

  8 cũng đang sử dụng các chỉ số số nguyên dựa trên số không trong

  name,department,birthday month
  John Smith,Accounting,November
  Erica Meyers,IT,March
  

  04. Đó là bởi vì chúng tôi đã không cho nó biết chỉ mục của bạn nên là gì

• Hơn nữa, nếu bạn nhìn vào các loại dữ liệu của các cột của chúng tôi, bạn sẽ thấy

  import csv
  
  with open['employee_birthday.txt'] as csv_file:
      csv_reader = csv.reader[csv_file, delimiter=',']
      line_count = 0
      for row in csv_reader:
          if line_count == 0:
              print[f'Column names are {", ".join[row]}']
              line_count += 1
          else:
              print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
              line_count += 1
      print[f'Processed {line_count} lines.']
  

  8 đã chuyển đổi chính xác các cột

  name,department,birthday month
  John Smith,Accounting,November
  Erica Meyers,IT,March
  

  11 và

  name,department,birthday month
  John Smith,Accounting,November
  Erica Meyers,IT,March
  

  12 thành số, nhưng cột

  name,department,birthday month
  John Smith,Accounting,November
  Erica Meyers,IT,March
  

  13 vẫn là một

  name,department,birthday month
  John Smith,Accounting,November
  Erica Meyers,IT,March
  

  2. Điều này dễ dàng được xác nhận trong chế độ tương tác

  >>>

  name,department,birthday month
  John Smith,Accounting,November
  Erica Meyers,IT,March
  

  7

Hãy giải quyết từng vấn đề một. Để sử dụng một cột khác làm chỉ mục

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

Bây giờ trường

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

Tiếp theo, hãy sửa kiểu dữ liệu của trường

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']

Lưu ý sự khác biệt trong đầu ra

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']

Ngày hiện được định dạng đúng, dễ dàng xác nhận trong chế độ tương tác

>>>

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']

Nếu tệp CSV của bạn không có tên cột trong dòng đầu tiên, bạn có thể sử dụng tham số tùy chọn

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']

Lưu ý rằng, vì tên cột đã thay đổi nên các cột được chỉ định trong tham số tùy chọn

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']

Viết tệp CSV bằng

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']

8

Tất nhiên, nếu bạn không thể lấy lại dữ liệu của mình từ

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']

Sự khác biệt duy nhất giữa mã này và mã đọc ở trên là cuộc gọi

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

import csv

with open['employee_birthday.txt'] as csv_file:
    csv_reader = csv.reader[csv_file, delimiter=',']
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print[f'Column names are {", ".join[row]}']
            line_count += 1
        else:
            print[f'\t{row[0]} works in the {row[1]} department, and was born in {row[2]}.']
            line_count += 1
    print[f'Processed {line_count} lines.']