Added countingsort.lua #38
Conversation
src/sorting/countingsort.lua
Outdated
| @@ -0,0 +1,58 @@ | |||
| function counting_sort(arr, key_function) | |||
There was a problem hiding this comment.
- This function should be
returned directly forrequireto work with this as expected rather than polluting globals; - I would rename
arrtolistfor consistency with the rest of the code. key_functionshould have a comment explaining what it does and what it defaults to. Especially since this sorting algorithm has special requirements (keys must be integers).
src/sorting/countingsort.lua
Outdated
| -- If no key_function is provided, use identity function | ||
| key_function = key_function or function(x) return x end | ||
|
|
||
| -- Step 1: Find the range of keys (min_key and max_key) |
There was a problem hiding this comment.
Code is self-explanatory, no comment needed. You can also simplify this to
local min_key, max_key = math.huge, -math.huge
for _, elem in ipairs(list) do
local key = key_function(elem)
min_key = math.min(min_key, key)
max_key = math.max(max_key, key)
end
src/sorting/countingsort.lua
Outdated
|
|
||
| -- Step 2: Initialize the count array | ||
| local count = {} | ||
| for i = min_key, max_key do |
There was a problem hiding this comment.
You get a problem here when arr is empty. Please add a special case to return early in that case.
Furthermore, as it currently is, this may (unnecessarily) populate the hash part if min_key is not 1, so please shift accordingly to prevent that.
src/sorting/countingsort.lua
Outdated
| end | ||
|
|
||
| -- Step 3: Count the occurrences of each key. In this case key is same as arr[i] | ||
| for i = 1, #arr do |
src/sorting/countingsort.lua
Outdated
| count[i] = 0 | ||
| end | ||
|
|
||
| -- Step 3: Count the occurrences of each key. In this case key is same as arr[i] |
There was a problem hiding this comment.
Unnecessary comment, also slightly misleading (keys are produced by the key function).
src/sorting/countingsort.lua
Outdated
| end | ||
| end | ||
|
|
||
| -- Sample array |
There was a problem hiding this comment.
Please add proper tests rather than some example code at the end of the file. This can essentially use the same tests as Radix Sort: check_sort(countingsort, nil, true), see https://github.com/TheAlgorithms/Lua/blob/main/.spec/sorting/sort_spec.lua.
|
Taken all the specified changes into account.. |
|
Made all the changes |
|
Can you please check this once.. |
src/sorting/countingsort.lua
Outdated
| max_key = math.max(max_key, key) | ||
| end | ||
|
|
||
| -- Initialize the count array |
There was a problem hiding this comment.
| -- Initialize the count array |
src/sorting/countingsort.lua
Outdated
| -- key_function to map elements to integer keys, defaults to identity | ||
| key_function | ||
| ) | ||
| -- Default to identity function if no key_function is provided |
There was a problem hiding this comment.
| -- Default to identity function if no key_function is provided |
src/sorting/countingsort.lua
Outdated
| -- Default to identity function if no key_function is provided | ||
| key_function = key_function or function(x) return x end | ||
|
|
||
| -- Handle empty list case |
There was a problem hiding this comment.
| -- Handle empty list case |
(If anything a useful comment would explain why not handling it early creates problems further down the line. The fact that we are handling it here early is obvious.)
There was a problem hiding this comment.
Ok I am sorry for this issue.....
Co-authored-by: Lars Müller <[email protected]>
Co-authored-by: Lars Müller <[email protected]>
|
Removed the comments that you mentioned . Retained the comments which have the core logic for this sorting technique. |
.spec/sorting/sort_spec.lua
Outdated
| end) | ||
| describe("Countingsort", function() | ||
| -- Test with multiple radii | ||
| local countingsort = require("sorting.countingsort") |
There was a problem hiding this comment.
| local countingsort = require("sorting.countingsort") |
|
Is it correct now? |
Please mention the label for hacktoberfest and gssoc' extd 24 . It will be helpful. I am willing to contribute further . Can you please help me if I have any doubts??