sorting error :"already exist" - python-3.x

Question

This code was suppose tu sort my desktop , path =/Users/nicolas/Desktop/prova/
and it works properly if the destination folder doesnt exist and the program create it ,
else if there is already a folder with the same name it give an error when he tries to move the files and it says
complete output:
.DS_Store
nltks
png
Scherm.png
Schermata 2018-03-28 alle 11.07.13.png
DS_Store
nltks
png
png
Traceback (most recent call last):
File "/Users/nicolas/Desktop/tts/work in progress/sorting machine.py", line 16, in
shutil.move(path+names[x],path+currentexp)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 292, in move
raise Error, "Destination path '%s' already exists" % real_dst
shutil.Error: Destination path '/Users/nicolas/Desktop/prova/png/Scherm.png' already exists
iMac:w
but i ve not any file in it with the ds_store estension and the "nltk" is just a folder that shouldnt move .
program
import os
import shutil
path = "/Users/nicolas/Desktop/prova/"
names = os.listdir(path)
for x in range (0,len(names)):
print names[x]
for x in range (0,len(names)):
exp = names[x].split(".")
currentexp = exp[-1]
print (currentexp)
if os.path.exists(path+currentexp):
shutil.move(os.path.join(path, names[x]), os.path.join(path,currentexp))
else:
os.makedirs(path+currentexp)
shutil.move(os.path.join(path, names[x]), os.path.join(path,currentexp))
# if names[x] not in os.path.exists(path+currentexp):
# shutil.move(path+names[x],path+curentexp)
thanks for the help

Answer 1

from the documentation:
If the destination is an existing directory, then src is moved inside that directory. If the destination already exists but is not a directory, it may be overwritten depending on os.rename() semantics
To sum it up, if the image exists in the target dir, and both source & target dirs are on the same filesystem, shutil.move can use os.rename, and os.rename fails because you cannot rename an object with the name of an already existing one. You have to delete the target first.
Here's how I'd rewrite it:
target_dir = os.path.join(path,currentexp)
if not os.path.exists(target_dir):
os.makedirs(target_dir)
try:
os.remove(os.path.join(target_dir, names[x]))
except OSError:
pass # cannot remove or doesn't exist, ignore
shutil.move(os.path.join(path, names[x]), target_dir)
this simpler code tries to delete the target file before performing shutil.move. Of course os.remove can fail, failure is trapped, then shutil.move fails because of another error, but that's beyond our scope