python - Why can't I write() multiple times on an open file? -

i trying delete words open file loop. each loop open file , remove line file , rewrite content file. finally, want generate contents original file.

the problem after loop, file not overwrote. remove 1 of words dictionary. seems when open file each iteration of loop, content of file not being updated each loop. please advise how handle file open/close in condition.

my code:

# want delete line contains pair dictionary. # example, if line contains "can_option" , "17", delete line.  dictionary = {"can_optin" : "17", "appprevaddrstreet": "33"} fname = "test.txt" infile = open(fname, 'r') data = infile.readlines() infile.close()  def readline(keyword, data, infile):     line in data:         linenumber = line.rsplit(none, 1)[-1]         # line contains "can_option" or "apppreaddrstreet",          # not write line file.         if keyword[0] in line , linenumber == keyword[1]:             print "removed: %s" % line         else:             infile.write(line)  # start delete line here. key in dictionary.keys():     infile= open(fname, 'w')     # write contents same file again , again until      # loop ends.     keyword = [key, dictionary[key]]     # keyword list contain ["con_option", "17"]     readline(keyword, data, infile)     infile.close() 

because not reading file. reading lines , saving in data variable , reading data, not written file -

dictionary = {"can_optin" : "17", "appprevaddrstreet": "33"} fname = "test.txt" infile = open(fname, 'r') data = infile.readlines() infile.close() 

to read current lines have read after writing file -

dictionary = {"can_optin" : "17", "appprevaddrstreet": "33"} fname = "test.txt"  def readline(keyword, data, infile):     line in data:         linenumber = line.rsplit(none, 1)[-1]         # line contains "can_option" or "apppreaddrstreet",          # not write line file.         if keyword[0] in line , linenumber == keyword[1]:             print "removed: %s" % line         else:             infile.write(line)  # start delete line here. key in dictionary.keys():     infile= open(fname, 'r+') # open in read/write mode     data = infile.readlines() # read again , updated data     [...]     keyword = [key, dictionary[key]]     [...]     readline(keyword, data, infile)     infile.close()