Dalam tutorial ini, kita akan belajar menulis fail CSV dengan format yang berbeza di Python dengan bantuan contoh.
Kami akan menggunakan csvmodul yang dibina di Python secara eksklusif untuk tugas ini. Tetapi pertama, kita perlu mengimport modul sebagai:
import csv
Kami telah membahas asas bagaimana menggunakan csvmodul untuk membaca dan menulis ke dalam fail CSV. Sekiranya anda tidak mempunyai idea untuk menggunakan csvmodul, lihat tutorial kami mengenai Python CSV: Baca dan Tulis fail CSV
Penggunaan Asas csv.writer ()
Mari kita lihat contoh asas penggunaan csv.writer()untuk menyegarkan pengetahuan sedia ada anda.
Contoh 1: Tulis ke dalam fail CSV dengan csv.writer ()
Andaikan kita mahu menulis fail CSV dengan entri berikut:
SN, Nama, Sumbangan 1, Linus Torvalds, Linux Kernel 2, Tim Berners-Lee, World Wide Web 3, Guido van Rossum, Pengaturcaraan Python
Inilah cara kami melakukannya.
import csv with open('innovators.csv', 'w', newline='') as file: writer = csv.writer(file) writer.writerow(("SN", "Name", "Contribution")) writer.writerow((1, "Linus Torvalds", "Linux Kernel")) writer.writerow((2, "Tim Berners-Lee", "World Wide Web")) writer.writerow((3, "Guido van Rossum", "Python Programming"))
Semasa kita menjalankan program di atas, fail innovators.csv dibuat dalam direktori kerja semasa dengan entri yang diberikan.
Di sini, kami telah membuka fail innovators.csv dalam mod penulisan menggunakan open()fungsi.
Untuk mengetahui lebih lanjut mengenai membuka fail di Python, lawati: Python File Input / Output
Seterusnya, csv.writer()fungsi digunakan untuk membuat writerobjek. Yang writer.writerow()fungsi kemudiannya digunakan untuk menulis baris tunggal ke fail CSV.
Contoh 2: Menulis Berbilang Baris dengan penulis ()
Sekiranya kita perlu menulis kandungan senarai 2 dimensi ke fail CSV, inilah cara kita dapat melakukannya.
import csv row_list = (("SN", "Name", "Contribution"), (1, "Linus Torvalds", "Linux Kernel"), (2, "Tim Berners-Lee", "World Wide Web"), (3, "Guido van Rossum", "Python Programming")) with open('protagonist.csv', 'w', newline='') as file: writer = csv.writer(file) writer.writerows(row_list)
Keluaran program adalah sama seperti dalam Contoh 1 .
Di sini, senarai 2 dimensi kami diteruskan ke writer.writerows()fungsi untuk menulis kandungan senarai ke fail CSV.
Sekarang mari kita lihat bagaimana kita boleh menulis fail CSV dalam format yang berbeza. Kami kemudian akan belajar bagaimana menyesuaikan csv.writer()fungsi untuk menulisnya.
Fail CSV dengan Pembatas Khusus
Secara lalai, koma digunakan sebagai pembatas dalam fail CSV. Walau bagaimanapun, sebilangan fail CSV boleh menggunakan pembatas selain koma. Beberapa yang popular adalah |dan .
Andaikan kita mahu menggunakannya |sebagai pembatas dalam fail inovator.csv Contoh 1 . Untuk menulis fail ini, kita dapat meneruskan delimiterparameter tambahan ke csv.writer()fungsi tersebut.
Mari kita ambil contoh.
Contoh 3: Tulis Fail CSV Mempunyai Pemisah Paip
import csv data_list = (("SN", "Name", "Contribution"), (1, "Linus Torvalds", "Linux Kernel"), (2, "Tim Berners-Lee", "World Wide Web"), (3, "Guido van Rossum", "Python Programming")) with open('innovators.csv', 'w', newline='') as file: writer = csv.writer(file, delimiter='|') writer.writerows(data_list)
Pengeluaran
SN | Nama | Sumbangan 1 | Linus Torvalds | Linux Kernel 2 | Tim Berners-Lee | World Wide Web 3 | Guido van Rossum | Pengaturcaraan Python
Seperti yang kita lihat, parameter pilihan delimiter = '|'membantu menentukan writerobjek yang harus dimiliki oleh fail CSV |sebagai pembatas.
Fail CSV dengan Petikan
Beberapa fail CSV mempunyai petikan di sekitar setiap atau beberapa entri.
Mari kita ambil quotes.csv sebagai contoh, dengan entri berikut:
"SN"; "Nama"; "Petikan" 1; "Buddha"; "Apa yang kita fikir kita menjadi" 2; "Mark Twain"; "Jangan sesekali menyesal apa pun yang membuat anda tersenyum" 3; "Oscar Wilde"; "Jadilah diri sendiri orang lain sudah diambil "
Menggunakan csv.writer()secara lalai tidak akan menambahkan petikan ini ke entri.
Untuk menambahkannya, kita harus menggunakan parameter pilihan lain yang dipanggil quoting.
Mari kita ambil contoh bagaimana sebut harga dapat digunakan di sekitar nilai bukan angka dan ;sebagai pembatas.
Contoh 4: Tulis fail CSV dengan petikan
import csv row_list = ( ("SN", "Name", "Quotes"), (1, "Buddha", "What we think we become"), (2, "Mark Twain", "Never regret anything that made you smile"), (3, "Oscar Wilde", "Be yourself everyone else is already taken") ) with open('quotes.csv', 'w', newline='') as file: writer = csv.writer(file, quoting=csv.QUOTE_NONNUMERIC, delimiter=';') writer.writerows(row_list)
Pengeluaran
"SN"; "Nama"; "Petikan" 1; "Buddha"; "Apa yang kita fikir kita menjadi" 2; "Mark Twain"; "Jangan sesekali menyesal apa pun yang membuat anda tersenyum" 3; "Oscar Wilde"; "Jadilah diri sendiri orang lain sudah diambil "
Di sini, fail quotes.csv dibuat dalam direktori kerja dengan entri di atas.
Seperti yang anda lihat, kami telah berlalu csv.QUOTE_NONNUMERICkepada quotingparameter. Ia adalah pemalar yang ditentukan oleh csvmodul.
csv.QUOTE_NONNUMERICmenentukan writerobjek yang harus ditambahkan petikan di sekitar entri bukan angka.
Terdapat 3 pemalar yang telah ditentukan yang boleh anda sampaikan ke quotingparameter:
csv.QUOTE_ALL- Menentukanwriterobjek untuk menulis fail CSV dengan tanda kutip di semua entri.csv.QUOTE_MINIMAL- Menentukanwriterobjek untuk hanya mengutip bidang yang berisi karakter khas ( pembatas , quotechar atau watak apa pun di lineterminator )csv.QUOTE_NONE- Menentukanwriterobjek yang tidak boleh disebutkan oleh entri. Ini adalah nilai lalai.
Fail CSV dengan watak sebut harga tersuai
We can also write CSV files with custom quoting characters. For that, we will have to use an optional parameter called quotechar.
Let's take an example of writing quotes.csv file in Example 4, but with * as the quoting character.
Example 5: Writing CSV files with custom quoting character
import csv row_list = ( ("SN", "Name", "Quotes"), (1, "Buddha", "What we think we become"), (2, "Mark Twain", "Never regret anything that made you smile"), (3, "Oscar Wilde", "Be yourself everyone else is already taken") ) with open('quotes.csv', 'w', newline='') as file: writer = csv.writer(file, quoting=csv.QUOTE_NONNUMERIC, delimiter=';', quotechar='*') writer.writerows(row_list)
Output
*SN*;*Name*;*Quotes* 1;*Buddha*;*What we think we become* 2;*Mark Twain*;*Never regret anything that made you smile* 3;*Oscar Wilde*;*Be yourself everyone else is already taken*
Here, we can see that quotechar='*' parameter instructs the writer object to use * as quote for all non-numeric values.
Dialects in CSV module
Notice in Example 5 that we have passed multiple parameters (quoting, delimiter and quotechar) to the csv.writer() function.
This practice is acceptable when dealing with one or two files. But it will make the code more redundant and ugly once we start working with multiple CSV files with similar formats.
As a solution to this, the csv module offers dialect as an optional parameter.
Dialect helps in grouping together many specific formatting patterns like delimiter, skipinitialspace, quoting, escapechar into a single dialect name.
It can then be passed as a parameter to multiple writer or reader instances.
Example 6: Write CSV file using dialect
Suppose we want to write a CSV file (office.csv) with the following content:
"ID"|"Name"|"Email" "A878"|"Alfonso K. Hamby"|"[email protected]" "F854"|"Susanne Briard"|"[email protected]" "E833"|"Katja Mauer"|"[email protected]"
The CSV file has quotes around each entry and uses | as a delimiter.
Instead of passing two individual formatting patterns, let's look at how to use dialects to write this file.
import csv row_list = ( ("ID", "Name", "Email"), ("A878", "Alfonso K. Hamby", "[email protected]"), ("F854", "Susanne Briard", "[email protected]"), ("E833", "Katja Mauer", "[email protected]") ) csv.register_dialect('myDialect', delimiter='|', quoting=csv.QUOTE_ALL) with open('office.csv', 'w', newline='') as file: writer = csv.writer(file, dialect='myDialect') writer.writerows(row_list)
Output
"ID"|"Name"|"Email" "A878"|"Alfonso K. Hamby"|"[email protected]" "F854"|"Susanne Briard"|"[email protected]" "E833"|"Katja Mauer"|"[email protected]"
Here, office.csv is created in the working directory with the above contents.
From this example, we can see that the csv.register_dialect() function is used to define a custom dialect. Its syntax is:
csv.register_dialect(name(, dialect(, **fmtparams)))
The custom dialect requires a name in the form of a string. Other specifications can be done either by passing a sub-class of the Dialect class, or by individual formatting patterns as shown in the example.
While creating the writer object, we pass dialect='myDialect' to specify that the writer instance must use that particular dialect.
The advantage of using dialect is that it makes the program more modular. Notice that we can reuse myDialect to write other CSV files without having to re-specify the CSV format.
Write CSV files with csv.DictWriter()
The objects of csv.DictWriter() class can be used to write to a CSV file from a Python dictionary.
The minimal syntax of the csv.DictWriter() class is:
csv.DictWriter(file, fieldnames)
Here,
file- CSV file where we want to write tofieldnames- alistobject which should contain the column headers specifying the order in which data should be written in the CSV file
Example 7: Python csv.DictWriter()
import csv with open('players.csv', 'w', newline='') as file: fieldnames = ('player_name', 'fide_rating') writer = csv.DictWriter(file, fieldnames=fieldnames) writer.writeheader() writer.writerow(('player_name': 'Magnus Carlsen', 'fide_rating': 2870)) writer.writerow(('player_name': 'Fabiano Caruana', 'fide_rating': 2822)) writer.writerow(('player_name': 'Ding Liren', 'fide_rating': 2801))
Output
The program creates a players.csv file with the following entries:
player_name,fide_rating Magnus Carlsen,2870 Fabiano Caruana,2822 Ding Liren,2801
The full syntax of the csv.DictWriter() class is:
csv.DictWriter(f, fieldnames, restval='', extrasaction='raise', dialect='excel', *args, **kwds)
To learn more about it in detail, visit: Python csv.DictWriter() class
CSV files with lineterminator
A lineterminator is a string used to terminate lines produced by writer objects. The default value is . You can change its value by passing any string as a lineterminator parameter.
However, the reader object only recognizes or as lineterminator values. So using other characters as line terminators is highly discouraged.
doublequote & escapechar in CSV module
In order to separate delimiter characters in the entries, the csv module by default quotes the entries using quotation marks.
So, if you had an entry: He is a strong, healthy man, it will be written as: "He is a strong, healthy man".
Similarly, the csv module uses double quotes in order to escape the quote character present in the entries by default.
If you had an entry: Go to "programiz.com", it would be written as: "Go to ""programiz.com""".
Here, we can see that each " is followed by a " to escape the previous one.
doublequote
It handles how quotechar present in the entry themselves are quoted. When True, the quoting character is doubled and when False, the escapechar is used as a prefix to the quotechar. By default its value is True.
escapechar
escapechar parameter is a string to escape the delimiter if quoting is set to csv.QUOTE_NONE and quotechar if doublequote is False. Its default value is None.
Example 8: Using escapechar in csv writer
import csv row_list = ( ('Book', 'Quote'), ('Lord of the Rings', '"All we have to decide is what to do with the time that is given us."'), ('Harry Potter', '"It matters not what someone is born, but what they grow to be."') ) with open('book.csv', 'w', newline='') as file: writer = csv.writer(file, escapechar='/', quoting=csv.QUOTE_NONE) writer.writerows(row_list)
Output
Book,Quote Lord of the Rings,/"All we have to decide is what to do with the time that is given us./" Harry Potter,/"It matters not what someone is born/, but what they grow to be./"
Here, we can see that / is prefix to all the " and , because we specified quoting=csv.QUOTE_NONE.
If it wasn't defined, then, the output would be:
Book,Quote Lord of the Rings,"""All we have to decide is what to do with the time that is given us.""" Harry Potter,"""It matters not what someone is born, but what they grow to be."""
Since we allow quoting, the entries with special characters(" in this case) are double-quoted. The entries with delimiter are also enclosed within quote characters.(Starting and closing quote characters)
The remaining quote characters are to escape the actual " present as part of the string, so that they are not interpreted as quotechar.
Note: The csv module can also be used for other file extensions (like: .txt) as long as their contents are in proper structure.
Bacaan yang Disyorkan: Baca Fail CSV di Python
