[New Concept Documents] : comparisons concept #2456 (#2733)

* Add blurb for Comparison concept

* Add introduction for Comparisons concept

* Add documentation for about.md for Comparisons concept on python track

* Add links to resources for comparisons concept in python track

* Update concepts/comparisons/.meta/config.json

Co-authored-by: BethanyG <[email protected]>

* Update concepts/comparisons/.meta/config.json

Co-authored-by: BethanyG <[email protected]>

* Update concepts/comparisons/.meta/config.json

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* Update concepts/comparisons/about.md

Co-authored-by: BethanyG <[email protected]>

* Update concepts/comparisons/links.json

Co-authored-by: Isaac Good <[email protected]>

* Update concepts/comparisons/links.json

Co-authored-by: Isaac Good <[email protected]>

* Update concepts/comparisons/introduction.md

Co-authored-by: BethanyG <[email protected]>

* Update description for official python operators

* Add note about short circuiting in comparison chaining

* changed unpacking declaration to simple declaration

* Update concepts/comparisons/about.md

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* Update example of membership test with better variable names

* Changed double quotes to single ones for consistency

* Update concepts/comparisons/about.md

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* Update concepts/comparisons/links.json

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* Add comparisons link at the bottom of the document

* Add note for comparison priority

* Update concepts/comparisons/about.md

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* Add link for arithmetic conversions

* Add example for complex number comparison

* Update concepts/comparisons/about.md

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* Update concepts/comparisons/about.md

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* Update concepts/comparisons/about.md

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* Add period and convert statement to h3

* Replace single letter variable with more verbose ones

* Update example of membership test

* Update concepts/comparisons/about.md

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* Minor apostrophe update

* Update concepts/comparisons/about.md

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* Update concepts/comparisons/about.md

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* Update concepts/comparisons/introduction.md

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* Update concepts/comparisons/about.md

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* Add chinese and korean strings for comparison

* Update concepts/comparisons/about.md

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* Update concepts/comparisons/about.md

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* Fix broken link due to mistyped word

* Remove code samples and change prose as per about.md

* Update concepts/comparisons/.meta/config.json

* Apply suggestions from code review

Markdown style standards: one-sentence-per-line changes.

Co-authored-by: Victor Goff <[email protected]>

* Change examples of chinese and korean words

* Mention Chinese and Korean in title case

* Update concepts/comparisons/about.md

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* Update concepts/comparisons/about.md

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Co-authored-by: Job van der Wal <[email protected]>

concepts/comparisons/.meta/config.json

@@ -1,5 +1,5 @@
 {
-  "blurb": "TODO: add blurb for this concept",
-  "authors": ["bethanyg", "cmccandless"],
+  "blurb": "Comparison operators evaluate two operand values, returning True or False based on whether the comparison condition is met.",
+  "authors": ["gurupratap-matharu", "bethanyg"],
   "contributors": []
 }

concepts/comparisons/about.md

@@ -1,2 +1,199 @@
-#TODO: Add about for this concept.
+# About
 
+A [comparison operator][comparisons] in Python (_also called a Python relational operator_), looks at the values of two operands and returns `True` or `False` based on whether the `comparison` condition is met.
+The most common comparison operators are `"<"`, `">"`, `"=="`, `">="`, `"<="`, and `"!="`.
+They all have the same priority (which is higher than that of the Boolean operations).
+
+```python
+>>> 7 > 5
+True
+>>> 99 < 100
+True
+>>> 4 < 4
+False
+>>> 4 <= 4
+True
+>>> 1 >= 1
+True
+>>> 5 == 5
+True
+>>> 6 != 6  # not equal to
+False
+>>> 5 != 6
+True
+>>> not 3 == 3  # interpreted as not(3 == 3)
+False
+```
+
+## Comparison Chaining
+
+Comparisons can be chained arbitrarily, e.g., `x < y <= z` is equivalent to `x < y` `and` `y <= z`, except that `y` is evaluated only once (but in both cases `z` is _not_ evaluated at all when `x < y` is found to be `False`).
+This is also called `short-circuit` evaluation which means the execution is stopped if the truth value of the expression has already been determined.
+Note that the evaluation of expression takes place from left to right.
+In python, short circuiting is supported by various boolean operators, functions and, in this case, comparison chaining.
+
+Also unlike `C`, expressions like `a < b < c` have the interpretation that is conventional in mathematics.
+
+```python
+>>> x = 2
+>>> y = 5
+>>> z = 10
+>>> x < y < z
+True
+>>> x < y > z
+False
+>>> x > y < z
+False
+```
+
+## Comparison between different data types
+
+Since everything in Python is an `object`, things can get interesting when objects of different types are compared.
+For example, the `str` value of a number is considered completely different from the `integer` or `floating-point` value.
+Python makes this distinction because strings are text, while `integers` and `floats` are numeric types.
+
+However, an `integer` **can** be considered equal to a `float`, as they are both numeric types that Python can implicitly convert to compare.
+
+For other numeric types, comparison operators are defined where they "make sense", but throw a `TypeError` if the underlying objects cannot be converted for comparison.
+For more information on the rules that python uses for numeric conversion, see [arithmetic conversions][arithmetic conversions] in the Python documentation.
+
+```python
+>>> 17 == '17'
+False
+>>> 17 == 17.0
+True
+>>> 17.0 == 0017.000
+True
+>>> complex(1, 2) == complex(1.0, 2.00)
+True
+```
+
+
+## Value Comparison
+
+The operators `<`, `>`, `==`, `>=`, `<=`, and `!=` compare the _values_ of two different objects.
+The objects do not need to have the same type.
+Remember that in Python every object has a `value` in addition to `type` and `identity`.
+
+### Following are comparison behaviour of most `built-ins` types.
+
+Numbers of built-in _numeric_ types such as `int`, `hex`, `ocal`, `binary`, `float`, `complex` and of the standard library types `fractions.Fraction` and `decimal.Decimal` can be compared within and across their types.
+
+Any ordered comparison of a number to a `NaN` (_not a number_) value is `False`.
+A counter-intuitive implication is that `NaN` never compares equal to `NaN`.
+
+```python
+>>> x = float('NaN')
+>>> x
+nan
+>>> 3 < x
+False
+>>> x < 3
+False
+>>> x == x
+False
+```
+
+Strings (`str`) are compared _lexicographically_ using their individual numerical Unicode code points (_the result of passing each code point in the `str` to the built-in function `ord()`_).
+`str` and `binary` sequences cannot be directly compared.
+
+```python
+>>> 'santa' < 'claus'
+False
+>>> 'Santa' < 'claus'
+True
+>>> ord('s')
+115
+>>> ord('S')
+83
+>>> ord('c')
+99
+>>> # let's try Chinese words
+>>> '你好' < '再见'  # hello < goodbye
+True
+>>> # check ord() of first letters
+>>> ord('你'), ord('再')
+(20320, 20877)
+>>>
+>>>
+>>> # let's try Korean words
+>>> '예쁜' < '아름다운'  # pretty < beautiful
+False
+>>> ord('예'), ord('아')
+(50696, 50500)
+```
+
+Collections like `list`, `set`, `tuple` and `dict` can also be compared -- provided they are of the same `type`, have the same length, and each _**pair**_ of corresponding elements within the collection are comparable.
+
+```python
+>>> [1, 2] == [1, 2]
+True
+>>> (1, 2) == [1, 2]
+False
+>>> [1, 2] < [1, 2, 3]
+True
+>>> # comparison of dicts
+>>> {'name': 'John', 'age': 19} == {'name': 'John', 'age': 18}
+False
+>>> {'name': 'John', 'age': 19} == {'name': 'John', 'age': 19}
+True
+```
+
+## Identity comparisons
+
+The operators `is` and `is not` test for an object's _identity_.
+An object's identity is determined using the `id()` function.
+
+`apple is orange` is `True` if and only if `apple` and `orange` are the same object.
+`apple is not orange` yields the inverse truth value.
+
+```python
+>>> my_fav_numbers = [1, 2, 3]
+>>> your_fav_numbers = my_fav_numbers
+>>> my_fav_numbers == your_fav_numbers
+True
+>>> id(my_fav_numbers)
+4462635008
+>>> id(your_fav_numbers)
+4462635008
+>>> my_fav_numbers is not your_fav_numbers
+False
+```
+
+## Membership test operations
+
+The operators `in` and `not in` test for _membership_.
+`fish in soup` evaluates to `True` if `fish` is a member of `soup`, and evaluates `False` otherwise.
+`fish not in soup` returns the negation, or _opposite of_ `fish in soup`.
+
+For the string and bytes types, `name` in `fullname` is `True` if and only if `name` is a substring of `fullname`.
+
+```python
+lucky_numbers = {11, 22, 33}
+>>> 22 in lucky_numbers
+True
+>>> 44 in lucky_numbers
+False
+>>>
+>>> employee = {
+    'name': 'John Doe',
+    'id': 67826,
+    'age': 33,
+    'title': 'ceo'
+    }
+>>> 'age' in employee
+True
+>>> 33 in employee
+False
+>>> 'lastname' not in employee
+True
+>>>
+>>> name = 'Super Batman'
+>>> 'Bat' in name
+True
+>>> 'Batwoman' in name
+False
+```
+
+[comparisons]: https://docs.python.org/3/library/stdtypes.html?highlight=comparisons#comparisons
+[arithmetic conversions]: https://docs.python.org/3/reference/expressions.html?highlight=number%20conversion#arithmetic-conversions

concepts/comparisons/introduction.md

@@ -1,2 +1,23 @@
-#TODO: Add introduction for this concept.
+# Introduction
 
+A [comparison operator][comparisons] in Python (_also called a Python relational operator_), looks at the values of two operands and returns `True` or `False` based on whether the `comparison` condition is met.
+The most common comparison operators are `"<"`, `">"`, `"=="`, `">="`, `"<="`, and `"!="`.
+They all have the same priority (which is higher than that of the Boolean operations)
+
+## Comparison Chaining
+
+Comparisons can be chained arbitrarily, e.g., `x < y <= z` is equivalent to `x < y` `and` `y <= z`, except that `y` is evaluated only once (but in both cases `z` is _not_ evaluated at all when `x < y` is found to be `False`).
+This is also called `short-circuit` evaluation which means the execution is stopped if the truth value of the expression has already been determined.
+Note that the evaluation of expression takes place from left to right.
+In python, short circuiting is supported by various boolean operators, functions and, in this case, comparison chaining.
+
+## Comparison of different data types
+
+Since everything in Python is an `object`, things can get interesting when objects of different types are compared.
+For example, the `str` value of a number is considered completely different from the `integer` or `floating-point` value.
+However, an `integer` **can** be considered equal to a `float`, as they are both numeric types that Python can implicitly convert to compare.
+For other numeric types, comparison operators are defined where they "make sense", but throw a `TypeError` if the underlying objects cannot be converted for comparison.
+For more information on the rules that python uses for numeric conversion, see [arithmetic conversions][arithmetic conversions] in the Python documentation.
+
+[comparisons]: https://docs.python.org/3/library/stdtypes.html?
+[arithmetic conversions]: https://docs.python.org/3/reference/expressions.html?highlight=number%20conversion#arithmetic-conversions

concepts/comparisons/links.json

@@ -1,18 +1,54 @@
 [
   {
-    "url": "http://example.com/",
-    "description": "TODO:  add new link (above) and write a short description here of the resource."
+    "url": "https://docs.python.org/3/reference/expressions.html#comparisons",
+    "description": "Comparisons in Python (Python language reference)"
   },
   {
-    "url": "http://example.com/",
-    "description": "TODO:  add new link (above) and write a short description here of the resource."
+    "url": "https://www.tutorialspoint.com/python/python_basic_operators.htm",
+    "description": "Python basic operators on Tutorials Point"
   },
   {
-    "url": "http://example.com/",
-    "description": "TODO:  add new link (above) and write a short description here of the resource."
+    "url": "https://data-flair.training/blogs/python-comparison-operators/",
+    "description": "Python comparison operators on Data Flair"
   },
   {
-    "url": "http://example.com/",
-    "description": "TODO:  add new link (above) and write a short description here of the resource."
+    "url": "https://www.python.org/dev/peps/pep-0207/",
+    "description": "PEP 207 to allow Operator Overloading for Comparison"
+  },
+  {
+    "url": "https://docs.python.org/3/reference/expressions.html#is-not",
+    "description": "Identity comparisons in Python (Python language reference)"
+  },
+  {
+    "url": "https://docs.python.org/3/library/operator.html",
+    "description": "Operators (Python Docs)"
+  },
+  {
+    "url": "https://docs.python.org/3/library/stdtypes.html#typesnumeric",
+    "description": "Numeric types (Python Docs)"
+  },
+  {
+    "url": "https://docs.python.org/3/library/decimal.html#decimal.Decimal",
+    "description": "Decimal types (Python Docs)"
+  },
+  {
+    "url": "https://docs.python.org/3/library/fractions.html#fractions.Fraction",
+    "description": "Fractions (Python Docs)"
+  },
+  {
+    "url": "https://docs.python.org/3/library/stdtypes.html#sequence-types-list-tuple-range",
+    "description": "Sequence types (Python Docs)"
+  },
+  {
+    "url": "https://docs.python.org/3/reference/datamodel.html#objects",
+    "description": "Python Object Model (Python docs)"
+  },
+  {
+    "url": "https://docs.python.org/3/reference/datamodel.html#customization",
+    "description": "Basic Customization (Python language reference)"
+  },
+  {
+    "url": "https://docs.python.org/3/reference/expressions.html#value-comparisons",
+    "description": "Value comparisons in Python (Python language reference)"
   }
 ]