Added a function to check ordering in ODA and DODA #344

Nora2412 · 2021-03-11T09:25:53Z

Appended algorithms file with is_sorted function. This will be useful to
check whether the array given is sorted or not.

References to other Issues or PRs or Relevant literature

Brief description of what is fixed or changed

Other comments

OneDimensionalArray. Appended algorithms file with is_sorted function. This will be useful to check whether the array given is sorted or not.

codecov · 2021-03-11T09:28:16Z

Codecov Report

Merging #344 (8730d80) into master (a21d00e) will increase coverage by 0.010%.
The diff coverage is 100.000%.

@@              Coverage Diff              @@
##            master      #344       +/-   ##
=============================================
+ Coverage   98.550%   98.561%   +0.010%     
=============================================
  Files           25        25               
  Lines         3243      3267       +24     
=============================================
+ Hits          3196      3220       +24     
  Misses          47        47

Impacted Files	Coverage Δ
pydatastructs/linear_data_structures/__init__.py	`100.000% <ø> (ø)`
pydatastructs/linear_data_structures/algorithms.py	`99.613% <100.000%> (+0.015%)`	⬆️
...ucts/miscellaneous_data_structures/disjoint_set.py	`100.000% <0.000%> (ø)`

Smit-create · 2021-03-11T10:48:53Z

pydatastructs/linear_data_structures/algorithms.py

+    >>> arr = OneDimensionalArray(int,[4,3,2,1])
+    >>> is_sorted(arr,0,3)


Suggested change

>>> arr = OneDimensionalArray(int,[4,3,2,1])

>>> is_sorted(arr,0,3)

>>> arr = OneDimensionalArray(int, [4, 3, 2, 1])

>>> is_sorted(arr, 0, 3)

Make suggested changes wherever appicable. Add a space after comma

Smit-create

Please apply this changes wherever required

Smit-create · 2021-03-11T12:35:59Z

pydatastructs/linear_data_structures/algorithms.py

+    for i in range(start+1,end+1):
+        if(array[i]<array[i-1]):


Suggested change

for i in range(start+1,end+1):

if(array[i]<array[i-1]):

for i in range(start + 1, end + 1):

if(array[i] < array[i - 1]):

czgdp1807 · 2021-03-11T12:51:42Z

This is a bit trivial. I mean checking if an array sorted or not in O(N) time isn't really helpful. For keeping time complexity constant we may need to maintain a state inside ODA class to track when the sort function was called on an array object. More or less it would be just like maintaining the history of the array. We can have this feature as something extra.

czgdp1807 · 2021-03-11T12:54:11Z

pydatastructs/linear_data_structures/algorithms.py

+
+    """
+    for i in range(start+1,end+1):
+        if(array[i]<array[i-1]):


This will not work with DODA (the dynamic arrays). An operator is defined in _comp (or something similar) in misc_util.py. Please use that here.
Moreover, we should allow a custom comparator (defaulting to <=) to check if an array is ordered according to some criteria specified by the passed comparator. The function can also be renamed to is_ordered.

Smit-create · 2021-03-11T15:59:00Z

For keeping time complexity constant we may need to maintain a state inside ODA class to track when the sort function was called on an array object

What if the user has'nt call sort function and has already given an sorted array as input?

This is a bit trivial. I mean checking if an array sorted or not in O(N) time isn't really helpful.

Presently, C++, also uses linear time complexity to check sortedness: http://www.cplusplus.com/reference/algorithm/is_sorted/

An operator is defined in _comp (or something similar) in misc_util.py. Please use that here.

This is something that would be good to have instead of using operators directly

Smit-create · 2021-03-12T10:59:24Z

Taking references from https://en.cppreference.com/w/cpp/algorithm/lower_bound and https://en.cppreference.com/w/cpp/algorithm/is_sorted_until:
We could do something like this:

def is_sorted(array, start, end, cmp=None):
    # cmp is a function that takes (a, b) and returns true if a is strictly less than b (a<b)
    if cmp is None:
         cmp = lambda a, b: (a < b) # we will use python defined <
    # algo
    return True/False

Similar thing can be done on #351
What do you think @czgdp1807 ?

czgdp1807 · 2021-03-12T11:45:02Z

pydatastructs/linear_data_structures/algorithms.py

@@ -787,3 +788,35 @@ def longest_common_subsequence(seq1: OneDimensionalArray, seq2: OneDimensionalAr
                    check_mat[i][j] = check_mat[i][j-1]

    return OneDimensionalArray(seq1._dtype, check_mat[row][col][-1])
+
+def is_sorted(array, start, end):


Please rename this function to is_ordered and accept an extra parameter comp.

czgdp1807 · 2021-03-12T11:45:58Z

What do you think @czgdp1807 ?

We should add is_ordered as it is more generic and allows more flexibility.

Smit-create · 2021-03-12T14:09:48Z

pydatastructs/linear_data_structures/algorithms.py

+    """
+    for i in range(start + 1, end + 1):
+        if(array[i] < array[i - 1]):
+            return False


Suggested change

"""

for i in range(start + 1, end + 1):

if(array[i] < array[i - 1]):

return False

"""

if comp is None:

comp = lambda a, b: a < b

for i in range(start + 1, end + 1):

if(comp(array[i], array[i - 1])):

return False

Smit-create · 2021-03-12T14:10:22Z

pydatastructs/linear_data_structures/tests/test_algorithms.py

+    arr4 = ODA(int, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], None)
+    output = is_ordered(arr4, 0, 9)
+    assert output == expected_result


Also add test cases for custom defined comp

Smit-create · 2021-03-14T07:15:40Z

@Nora2412 Please use python -m pytest to check locally which test is failing (presently due to trailing space/tab on some line)

Smit-create · 2021-03-15T16:49:37Z

If you have trailing whitespace it will show errors. This one will fix unwanted spaces:
$ ./bin/strip_whitespace <file>

Smit-create

This looks good. Please address few suggestions

Smit-create · 2021-03-16T17:27:08Z

pydatastructs/linear_data_structures/tests/test_algorithms.py

+    arr = ODA(int,[1,2,5,6])
+    output = is_sorted(arr,0,len(arr)-1)
+    assert output == expected_result


Suggested change

arr = ODA(int,[1,2,5,6])

output = is_sorted(arr,0,len(arr)-1)

assert output == expected_result

arr = ODA(int, [1, 2, 5, 6])

output = is_sorted(arr, 0, len(arr) - 1)

assert output == expected_result

Apply this change whereever necessary

Smit-create · 2021-03-16T17:27:33Z

pydatastructs/linear_data_structures/tests/test_algorithms.py

+    arr4 = ODA(int,[1,2,3,4,5,6,7,8,9,10])
+    output = is_sorted(arr4,0,9)
+    assert output == expected_result


Also add tests for user-defined comp

Nora2412 · 2021-03-18T03:37:36Z

@Smit-create can you please review and let me know if any further changes are required.

czgdp1807 · 2021-03-19T05:49:06Z

Will merge once the tests pass.

Add a function to check sorting of

d836728

OneDimensionalArray. Appended algorithms file with is_sorted function. This will be useful to check whether the array given is sorted or not.

Smit-create reviewed Mar 11, 2021

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czgdp1807 reviewed Mar 11, 2021

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Smit-create added easy enhancement New feature or request linear_data_structures.algorithms labels Mar 11, 2021

czgdp1807 reviewed Mar 12, 2021

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Smit-create reviewed Mar 12, 2021

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Smit-create mentioned this pull request Mar 12, 2021

upper_bound and lower_bound functions added #351

Merged

czgdp1807 added medium and removed easy labels Mar 12, 2021

Nora2412 force-pushed the pr1 branch from 90cff6f to d836728 Compare March 15, 2021 17:22

Nora2412 added 2 commits March 16, 2021 22:53

Update algorithms.py

51d7b76

Update __init__.py

0b1a111

Smit-create reviewed Mar 16, 2021

View reviewed changes

Nora2412 and others added 5 commits March 16, 2021 22:59

Update test_algorithms.py

5150c6f

Added is_ordered function to check order of ODA

5c6d4bd

Merge branch 'pr1' of https://github.com/Nora2412/pydatastructs into pr1

69dc790

Update algorithms.py

52596f7

Update algorithms.py

5c352ee

Minor changes

dbbe5a5

czgdp1807 changed the title ~~Add a function to check sorting of One Dimensional Array~~ Added a function to check ordering in ODA and DODA Mar 19, 2021

docs corrected

8730d80

czgdp1807 merged commit 5488001 into codezonediitj:master Mar 19, 2021

		>>> arr = OneDimensionalArray(int,[4,3,2,1])
		>>> is_sorted(arr,0,3)

Added a function to check ordering in ODA and DODA #344

Added a function to check ordering in ODA and DODA #344

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Nora2412 commented Mar 11, 2021

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