A simple csv code - Printable Version

A simple csv code - Printable Version

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A simple csv code - Truman - Dec-21-2018

import csv
csvFile = open("c:\Python36\files\test.csv", 'w+')
try:
	writer = csv.writer(csvFile)
	writer.writerow(('number', 'number plus 2', 'number times 2'))
	for i in range(10):
		writer.writerow(i, i+2, i*2)
finally:
	csvFile.close()

Error:Traceback (most recent call last):
  File "C:\Python36\kodovi\csvv.py", line 9, in <module>
    csvFile = open("c:\Python36\files\test.csv", 'w+')
OSError: [Errno 22] Invalid argument: 'c:\\Python36\x0ciles\test.csv'

What did I do wrong? Tried several combinations with several paths but it gave me similar error. I didn't create files directory, expecting that it will be created as per this code.

RE: A simple csv code - nilamo - Dec-21-2018

The backslash is an escape character. So you need to either:
1) escape it: "c:\\Python36\\files\\test.csv"
2) use a raw string: r"c:\Python36\files\test.csv"
3) use forward slashes: "c:/Python36/files/test.csv"

You can tell this from the error message, where instead of "files", it's looking for a folder called "Python36\x0ciles".

RE: A simple csv code - ichabod801 - Dec-21-2018

Backslash is an escape character in Python. You can do three things: use forward slashes instead (they'll work on any system), use two backslashes everytime you want one, or make it a raw string that ignores escape characters by putting an r in front it.

RE: A simple csv code - buran - Dec-21-2018

Don't use backslash as separator, It's an escape char, so '\t' is actually Tab.
make "c:\Python36\files\test.csv" raw string - r"c:\Python36\files\test.csv"

use forward slash "c:/Python36/files?test.csv"

or escape the backslash "c:\\Python36\\files\\test.csv"

I think this deserves a thread in Common pitfalls and what to do :-)

RE: A simple csv code - Truman - Dec-21-2018

Thank you, I opted for a raw string and now get this error:

Error:Traceback (most recent call last):
  File "C:\Python36\kodovi\csvv.py", line 14, in <module>
    writer.writerow(i, i+2, i*2)
TypeError: writerow() takes exactly one argument (3 given)

strange that it takes only one argument...

RE: A simple csv code - buran - Dec-21-2018

you must supply list, tuple, etc.
writer.writerow((i, i+2, i*2))

as an alternative to

for i in range(10):
    writer.writerow((i, i+2, i*2))

you can do

writer.writerows((i, i+2, i*2) for i in range(10))

Some more advise - use with context manager to open the file (it will close it for you at the end automatically). You don't need the try/finally

import csv
with open(r"c:\Python36\files\test.csv", 'w') as csv_file:
    writer = csv.writer(csv_file)
    writer.writerow(('number', 'number plus 2', 'number times 2'))
    writer.writerows((i, i+2, i*2) for i in range(10))

RE: A simple csv code - woooee - Dec-21-2018

Quote:strange that it takes only one argument...

There are many examples of the expected syntax format on the web
.

RE: A simple csv code - Truman - Dec-21-2018

What is strange is that I found this example in the pretty known book on web scraping.

RE: A simple csv code - Truman - Dec-21-2018

practising csv I wrote this code:

with open('example.csv', 'r') as exampleFile:
	exampleReader = csv.reader(exampleFile)
	for line in exampleReader:
		print('Line #' + str(exampleReader.line_num) + ' ' + str(line))

this is what I get:

Output:Line #1 ['4/5/2015 13:34\tApples\t        73']
Line #2 ['4/5/2015 3:41\tCherries        85\t']
Line #3 ['4/6/2015 12:46\tPears\t        14']
Line #4 ['4/8/2015 8:59\tOranges\t        52']
Line #5 ['4/10/2015 2:07\tApples\t       152']
Line #6 ['4/10/2015 18:10\tBananas\t        23']
Line #7 ['4/10/2015 2:40\tStrawberries\t98']

Do you know what to do to eliminate this '\t'? I don't understand why this tab sign appears at all since I didn't add it.

RE: A simple csv code - gehrenfeld - Dec-22-2018

exampleReader = csv.reader(exampleFile, delimiter='\t')