Reputation: 12486
I want to cast data like [1,2,'a','He said "what do you mean?"']
to a CSV-formatted string.
Normally one would use csv.writer()
for this, because it handles all the crazy edge cases (comma escaping, quote mark escaping, CSV dialects, etc.) The catch is that csv.writer()
expects to output to a file object, not to a string.
My current solution is this somewhat hacky function:
def CSV_String_Writeline(data):
class Dummy_Writer:
def write(self,instring):
self.outstring = instring.strip("\r\n")
dw = Dummy_Writer()
csv_w = csv.writer( dw )
csv_w.writerow(data)
return dw.outstring
Can anyone give a more elegant solution that still handles the edge cases well?
Edit: Here's how I ended up doing it:
def csv2string(data):
si = StringIO.StringIO()
cw = csv.writer(si)
cw.writerow(data)
return si.getvalue().strip('\r\n')
Upvotes: 177
Views: 169170
Reputation: 408
since i use this quite a lot to stream results asynchronously from sanic back to the user as csv data i wrote the following snippet for Python 3.
The snippet lets you reuse the same StringIo buffer over and over again.
import csv
from io import StringIO
class ArgsToCsv:
def __init__(self, seperator=","):
self.seperator = seperator
self.buffer = StringIO()
self.writer = csv.writer(self.buffer)
def stringify(self, *args):
self.writer.writerow(args)
value = self.buffer.getvalue().strip("\r\n")
self.buffer.seek(0)
self.buffer.truncate(0)
return value + "\n"
example:
csv_formatter = ArgsToCsv()
output += csv_formatter.stringify(
10,
"""
lol i have some pretty
"freaky"
strings right here \' yo!
""",
[10, 20, 30],
)
Check out further usage at the github gist: source and test
Upvotes: 9
Reputation: 955
i adopt the answer of @user2099484 above, with a small amendment for unicode
import csv, io
def csv2string(data):
si = io.BytesIO()
cw = csv.writer(si)
data = [f.encode('utf-8') if type(f) == unicode else f for f in data]
cw.writerow(data)
return si.getvalue().strip('\r\n')
data=[1,2,'a','He said "what do you mean?"']
print csv2string(data)
data2=[1,2,u'שלום','He said "what do you mean?"']
print csv2string(data2)
Upvotes: 1
Reputation: 500883
You could use StringIO
instead of your own Dummy_Writer
:
This module implements a file-like class,
StringIO
, that reads and writes a string buffer (also known as memory files).
There is also cStringIO
, which is a faster version of the StringIO
class.
Upvotes: 73
Reputation: 4559
I found the answers, all in all, a bit confusing. For Python 2, this usage worked for me:
import csv, io
def csv2string(data):
si = io.BytesIO()
cw = csv.writer(si)
cw.writerow(data)
return si.getvalue().strip('\r\n')
data=[1,2,'a','He said "what do you mean?"']
print csv2string(data)
Upvotes: 7
Reputation: 17
import csv
from StringIO import StringIO
with open('file.csv') as file:
file = file.read()
stream = StringIO(file)
csv_file = csv.DictReader(stream)
Upvotes: -2
Reputation: 10090
Here's the version that works for utf-8. csvline2string for just one line, without linebreaks at the end, csv2string for many lines, with linebreaks:
import csv, io
def csvline2string(one_line_of_data):
si = BytesIO.StringIO()
cw = csv.writer(si)
cw.writerow(one_line_of_data)
return si.getvalue().strip('\r\n')
def csv2string(data):
si = BytesIO.StringIO()
cw = csv.writer(si)
for one_line_of_data in data:
cw.writerow(one_line_of_data)
return si.getvalue()
Upvotes: 0
Reputation: 336468
In Python 3:
>>> import io
>>> import csv
>>> output = io.StringIO()
>>> csvdata = [1,2,'a','He said "what do you mean?"',"Whoa!\nNewlines!"]
>>> writer = csv.writer(output, quoting=csv.QUOTE_NONNUMERIC)
>>> writer.writerow(csvdata)
59
>>> output.getvalue()
'1,2,"a","He said ""what do you mean?""","Whoa!\nNewlines!"\r\n'
Some details need to be changed a bit for Python 2:
>>> output = io.BytesIO()
>>> writer = csv.writer(output)
>>> writer.writerow(csvdata)
57L
>>> output.getvalue()
'1,2,a,"He said ""what do you mean?""","Whoa!\nNewlines!"\r\n'
Upvotes: 268