2048 merge function

From: Principles of Computing Part 1 Course on Coursera

I got -2 pts on my OWLTEST which uses Pylint for style guide. The error states:


Too many branches (17/12)
function "merge", line 7

What does that mean?

I worked really hard on making this program work and wrote it from scratch. I would also like to know if there are some techniques to make this cleaner and/or utilize best practices. I know there are probably ways to write this in a better way because right now my code looks really messy.

I wish to improve on code style, performance, and readability.

```
# -- coding: utf-8 --
"""
Created on Thu Sep 3 17:55:56 2015
2048_merge_attempt1.py
@author: Rafeh
"""
def merge(nums):
'''
Takes a list as input
returns merged pairs with
non zero values shifted to the left.
[2, 0, 2, 4] should return [4, 4, 0, 0]
[0, 0, 2, 2] should return [4, 0, 0, 0]
[2, 2, 0, 0] should return [4, 0, 0, 0]
[2, 2, 2, 2, 2] should return [4, 4, 2, 0, 0]
[8, 16, 16, 8] should return [8, 32, 8, 0]
'''
slide = [] # Append non-zeroes first
for num in nums:
if num != 0:
slide.append(num)
for num in nums:
if num == 0:
slide.append(num)
pairs = []
for idx, num in enumerate(slide):
if idx == len(slide)-1:
pairs.append(num)
if len(pairs) != len(nums):
pairs.append(0)
break
if num == slide[idx+1]:
if num != 0:
pairs.append(num*2)
slide[idx+1] -= slide[idx+1]
# slide[idx+1], slide[idx+2] = slide[idx+2], slide[idx+1]
else:
pairs.append(num)
else:
pairs.append(num) # Even if they don't match you must append
slide = [] # Append non-zeroes first
for num in pairs:
if num != 0:
slide.append(num)
for num in nums:
if num == 0:
slide.append(num)
for _ in range(

Use automatic tests

In your doc-string you state:

[2, 0, 2, 4] should return [4, 4, 0, 0]
    [0, 0, 2, 2] should return [4, 0, 0, 0]
    [2, 2, 0, 0] should return [4, 0, 0, 0]
    [2, 2, 2, 2, 2] should return [4, 4, 2, 0, 0]
    [8, 16, 16, 8] should return [8, 32, 8, 0]

But I either

• Test all this inputs manually (very boring)

• Trust you (nothing personal but code accuracy should not be based on personal subjective trust)

Instead you could have written:

>>> merge([2, 0, 2, 4])
[4, 4, 0, 0]
>>> merge([0, 0, 2, 2])
[4, 0, 0, 0]
>>> merge([2, 2, 0, 0])
[4, 0, 0, 0]
>>> merge([2, 2, 2, 2, 2])
[4, 4, 2, 0, 0]
>>> merge([8, 16, 16, 8])
[8, 32, 8, 0]

This way doctest will run all the test automatically each time the module is executed. This technique will save you much tedious manual testing in the future.

StackExchange Code Review Q#103764, answer score: 11