CODEWITHSUNDEEP
pythoncsvunicodeutf-8
add-semi-colons
add-semi-colons

Reputation: 18810

Python: Write Unicode to CSV using UnicodeWriter

Python Documents have following code example on writing unicode to csv file. I think it has mentioned there that this is the way to do since csv module can't handle unicode strings.

class UnicodeWriter:
    """
    A CSV writer which will write rows to CSV file "f",
    which is encoded in the given encoding.
    """

    def __init__(self, f, dialect=csv.excel, encoding="utf-8", **kwds):
        # Redirect output to a queue
        self.queue = cStringIO.StringIO()
        self.writer = csv.writer(self.queue, dialect=dialect, **kwds)
        self.stream = f
        self.encoder = codecs.getincrementalencoder(encoding)()

    def writerow(self, row):
        self.writer.writerow([s.encode("utf-8") for s in row])
        # Fetch UTF-8 output from the queue ...
        data = self.queue.getvalue()
        data = data.decode("utf-8")
        # ... and reencode it into the target encoding
        data = self.encoder.encode(data)
        # write to the target stream
        self.stream.write(data)
        # empty queue
        self.queue.truncate(0)

    def writerows(self, rows):
        for row in rows:
            self.writerow(row)

I am writing more than one file and to keep it simple I have only put the section of my code to demonstrate how I use above class in my code:

def write(self):
    """
    Outputs the dataset to a csv.
    """
    f = codecs.open(self.filename, 'a')
    writer = UnicodeWriter(f)
    #with open(self.filename, 'a', encoding='utf-8') as f:
    if self.headers and not self.written:
        writer.writerow(self.headers)
        self.written = True
    for record in self.records[self.last_written:]:
        print record
        writer.writerow(record)
    self.last_written = len(self.records)
    f.close()

This is a method inside a class coll dataset which prepare the dataset prior to writing to csv, previously I was using writer = csv.writer(f) but due to codec errors I change my code to use `UnicodeWriter class.

But my problem is that when I open the csv file, I get the following: 

some_header
B,r,ë,k,ò,w,n,i,k,_,b,s
B,r,ë,k,ò,w,n,i,k,_,c,s
B,r,ë,k,ò,w,n,i,k,_,c,s,b
B,r,ë,k,ò,w,n,i,k,_,d,e
B,r,ë,k,ò,w,n,i,k,_,d,e,-,1
B,r,ë,k,ò,w,n,i,k,_,d,e,-,2
B,r,ë,k,ò,w,n,i,k,_,d,e,-,3
B,r,ë,k,ò,w,n,i,k,_,d,e,-,4
B,r,ë,k,ò,w,n,i,k,_,d,e,-,5
B,r,ë,k,ò,w,n,i,k,_,d,e,-,M
B,r,ë,k,ò,w,n,i,k,_,e,n
B,r,ë,k,ò,w,n,i,k,_,e,n,-,1
B,r,ë,k,ò,w,n,i,k,_,e,n,-,2

Where as these rows should actually should be something like Brëkòwnik_de-1 I am not really whats happening.

To give a basic idea of how the data has been generated I would add the following line: title = unicode(row_page_title['page_title'], 'utf-8')

Upvotes: 3

Views: 9991

Answers (1)

Paulo Scardine
Paulo Scardine

Reputation: 77251

This symptom points to something like feeding a string into a function/method that is expecting a list or tuple.

The writerows method is expecting a list of lists, and writerow expects a list (or tuple) containing the field values. Since you are feeding it a string, and a string can mimic a list of characters when you iterate over it, you get a CSV with one character in each column.

If your CSV has just one column, you should use writer.writerow([data]) instead of writer.writerow(data). Some may question if you really need the csv module if you have only one column, but the csv module will handle things like a record containing funny stuff (CR/LF and others), so yes, it is a good idea.

Upvotes: 4

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