Python CSV reader TypeError: string pattern on bytes object -

i trying use python csv reader first time. have method asks user select file want parse , passes file path parse method:

def parse(filename):         parsedfile = []         open(filename, 'rb') csvfile:                 dialect = csv.sniffer().sniff(csvfile.read(), delimiters=';,|')                 csvfile.seek(0)                 reader = csv.reader(csvfile, dialect)                  line in reader:                     parsedfile.append(line)                 return(parsedfile)  def selectfile():         print('start selectfile method')         localpath = os.getcwd() + '\files'         print(localpath)         filea in os.listdir(localpath):                 print (filea)          test = false         while test == false:                 fileb = input('which file deid? \n')                 conjoinedpath = os.path.join(localpath, fileb)                 test = os.path.isfile(conjoinedpath)           userinput = input('please enter number corresponding client ' + fileb + ' belongs to. \n\nacceptable options are: \n1.a \n2.b \n3.c \n4.d \n5.e \n')         client = ''         if (userinput == '1'):                 client = 'a'         elif (userinput == '2'):                 client = 'b'         elif (userinput == '3'):                 client = 'cservices'         elif (userinput == '4'):                 client = 'd'         elif (userinput == '5'):                 client = 'e'         return(client, conjoinedpath)    def main():        x, y = selectfile()         parse(y)   if __name__ == '__main__':         main() 

all of seems working intended, getting a:

typeerror: can't use string pattern on bytes-like object  

when trying open filename (line 3 in code). have tried convert filename to both string-type , byte-type , neither seem work.

here output:

>>>  start selectfile method c:\pythonscripts\deid\files 89308570_201601040630verifyppn.txt 89339985_201601042316verifyppn.txt file deid?  89339985_201601042316verifyppn.txt please enter number corresponding client 89339985_201601042316verifyppn.txt belongs to.   acceptable options are:  1.client 2.client b 3.client c 4.client d 5.client e 3 traceback (most recent call last):   file "c:\pythonscripts\deid\deidva1.py", line 107, in <module>     main()   file "c:\pythonscripts\deid\deidva1.py", line 103, in main     parse(y)   file "c:\pythonscripts\deid\deidva1.py", line 63, in parse     dialect = csv.sniffer().sniff(csvfile.read(), delimiters=';,|')   file "c:\python34\lib\csv.py", line 183, in sniff     self._guess_quote_and_delimiter(sample, delimiters)   file "c:\python34\lib\csv.py", line 224, in _guess_quote_and_delimiter     matches = regexp.findall(data) typeerror: can't use string pattern on bytes-like object >>>  

i not sure doing wrong.

it not filename blamed here, fact opening file with:

with open(filename, 'rb') csvfile: 

where 'rb' mode specifies file opened in binary mode, is, contents of file treated byte objects. documentation:

'b' appended mode opens file in binary mode: data read , written in form of bytes objects. mode should used files don’t contain text.

then attempt search within csv.sniff().sniff() string pattern, and, typeerror gracefully points out, isn't allowed.

removing b mode , using r trick.

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note: python 2.x doesn't exhibit behavior on unix machines. result of segregation of bytes , str objects distinct types in 3.x.