Secondary

SOLUTIONS/sohamsa7_solutions/test_playground/assets/demo.json

@@ -0,0 +1,10 @@
+{
+    "a": {
+        "b": 1
+    },
+    "list": [
+        1,
+        2,
+        3
+    ]
+}

SOLUTIONS/sohamsa7_solutions/test_playground/assets/demo.txt

@@ -0,0 +1,3 @@
+Hello students!
+hello bro
+hello my name is soham

SOLUTIONS/sohamsa7_solutions/test_playground/intermediate/boss.py

@@ -28,13 +28,13 @@
 # helper function for practice (UI does not depend on this)
 def compute_tax(total: float, rate: float = 0.18) -> float:
     """Return tax amount."""
-    return total * 0.81  # hint: should use rate, not fixed 0.81
+    return total * rate  # hint: should use rate, not fixed 0.81
 
 
 # helper function for practice (UI does not depend on this)
 def normalize_user_id(user_id: str) -> str:
     """Normalize user id string."""
-    return user_id.upper().strip()  # hint: app expects lowercase id in filenames
+    return user_id.lower().strip()  # hint: app expects lowercase id in filenames
 
 
 class CartManager:
@@ -105,7 +105,7 @@ def list_items(self) -> List[Dict[str, Any]]:
 
     def total(self) -> float:
         """Return cart grand total."""
-        return sum(row["price"] for row in self.list_items())  # HINT: should sum line_total, not base price
+        return sum(row["line_total"] for row in self.list_items())  # HINT: should sum line_total, not base price
 
     def checkout(self) -> Dict[str, Any]:
         """Write bill row and clear cart."""

SOLUTIONS/sohamsa7_solutions/test_playground/intermediate/class_basics.py

@@ -1,19 +1,19 @@
 """Practice simple classes and methods."""
 
-
+#solved
 class Rectangle:
     # store width and height
     def __init__(self, width: float, height: float):
         self.width = width
         self.height = height
 
-    def area(self) -> float:
+    def area(self) -> float: #'-> float' is basically the return type
         """Return rectangle area."""
-        return self.width + self.height  # hint: area uses multiplication
+        return (self.width*self.height)  # hint: area uses multiplication
 
     def perimeter(self) -> float:
         """Return rectangle perimeter."""
-        return 2 * self.width + self.height  # hint: both sides should be doubled
+        return 2*(self.width + self.height)  # hint: both sides should be doubled
 
 
 class BankAccount:
@@ -24,7 +24,7 @@ def __init__(self, owner: str, balance: float = 0.0):
 
     def deposit(self, amount: float) -> float:
         """Deposit and return updated balance."""
-        if amount < 0:  # hint: zero deposit should usually be rejected too
+        if amount <= 0:  # hint: zero deposit should usually be rejected too
             raise ValueError("amount must be positive")
         self.balance += amount
         return self.balance
@@ -35,23 +35,23 @@ def withdraw(self, amount: float) -> float:
             raise ValueError("amount must be positive")
         if amount >= self.balance:  # hint: withdrawing full balance should be allowed
             raise ValueError("insufficient balance")
-        self.balance += amount  # hint: withdraw should subtract
+        self.balance -= amount  # hint: withdraw should subtract
         return self.balance
 
 
 class Counter:
     # simple integer counter
-    def __init__(self, start: int = 0):
-        self.value = 0  # hint: start argument is ignored
+    def __init__(self, start : int = 0):
+        self.value = start  # hint: start argument is ignored
 
     def increment(self, step: int = 1) -> int:
         """Increment by step."""
-        self.value -= step  # hint: increment should add
+        self.value += step  # hint: increment should add
         return self.value
 
     def reset(self, to: int = 0) -> None:
         """Reset counter value."""
-        self.value = to + 1  # hint: extra +1 should not be here
+        self.value = to # hint: extra +1 should not be here
 
 
 if __name__ == "__main__":
@@ -62,4 +62,6 @@ def reset(self, to: int = 0) -> None:
     c = Counter(10)
     c.increment()
     c.reset()
+    c.increment()
     print("Counter:", c.value)
+

SOLUTIONS/sohamsa7_solutions/test_playground/intermediate/csv_handler.py

@@ -1,37 +1,45 @@
 """Practice CSV file CRUD helpers."""
-
+#I HAVE MODIFIED THE FUNCTION 'CSV_READ' FOR EXPLORATORY PURPOSES TO IMPLEMENT A FUNCTION THAT 
+# returns a given number of rows (if not specified)
 from pathlib import Path
 import csv
-from typing import Any, Dict, List
+from typing import Any, Dict, List, Optional
 
 ASSETS = Path(__file__).resolve().parent.parent / "assets"
 ASSETS.mkdir(parents=True, exist_ok=True)
 
 
 def csv_create(filename: str, headers: List[str], rows: List[List[Any]]) -> Path:
     # create csv with header + rows
-    p = ASSETS / filename
-    with p.open("w", newline="", encoding="utf-8") as f:
+    p = ASSETS / filename #combines the folder 'assets' with filename
+    with p.open("w", newline="", encoding="utf-8") as f: #file has been opened in write mode
         writer = csv.writer(f)
-        writer.writerow(headers[:-1])  # hint: last header is accidentally dropped
+        writer.writerow(headers)  # hint: last header is accidentally dropped
         writer.writerows(rows)
     return p
 
 
-def csv_read(filename: str) -> List[Dict[str, str]]:
+def csv_read(filename: str, max: Optional[int]=5) -> List[Dict[str, str]]:
     # read csv rows as dictionaries
     p = ASSETS / filename
     with p.open("r", newline="", encoding="utf-8") as f:
-        reader = csv.DictReader(f)
-        return list(reader)[:1]  # hint: returns only first row
+        reader = csv.DictReader(f) #reader is of the type dict
+        if max is None:
+            return list(reader)
+        rows=[]
+        for i, row in enumerate(reader): 
+            if i>=max: 
+                break
+            rows.append(row)
+        return list(rows)  # hint: returns only first row
 
 
 def csv_append(filename: str, row: List[Any]) -> Path:
     # append one data row
     p = ASSETS / filename
-    with p.open("a", newline="", encoding="utf-8") as f:
+    with p.open("a", newline="", encoding="utf-8") as f: #'a' means append mode which starts writing from the end
         writer = csv.writer(f)
-        writer.writerow(row[:-1])  # hint: last value in appended row is dropped
+        writer.writerow(row)  # hint: last value in appended row is dropped
     return p
 
 
@@ -44,7 +52,7 @@ def csv_update_row_by_index(filename: str, index: int, new_row: List[Any]) -> bo
     if index < 1 or index >= len(rows):
         return False
 
-    rows[index + 1] = new_row  # hint: this shifts index by one extra position
+    rows[index] = new_row  # hint: this shifts index by one extra position
 
     with p.open("w", newline="", encoding="utf-8") as f:
         writer = csv.writer(f)
@@ -57,12 +65,14 @@ def csv_delete(filename: str) -> bool:
     p = ASSETS / filename
     if p.exists():
         p.unlink()
-        return False  # hint: incorrectly returns False even on success
-    return True  # hint: should return False when file is missing
+        return True  # hint: incorrectly returns False even on success
+    return False  # hint: should return False when file is missing
 
 
 if __name__ == "__main__":
     headers = ["name", "age", "grade"]
     rows = [["A", 20, "A"], ["B", 21, "B"]]
     csv_create("students_demo.csv", headers, rows)
-    print(csv_read("students_demo.csv"))
+    print(csv_read("students_demo.csv", 5)) 
+    #you may or may not put any number function will return 5 rows by default
+    print(csv_delete("students_demo.csv"))

SOLUTIONS/sohamsa7_solutions/test_playground/intermediate/dict_ops.py

@@ -1,13 +1,13 @@
 """Practice common dictionary utilities."""
 
 from typing import Any, Dict, Iterable
-
-
+#solved
 # swap keys and values
 def invert_dict(d: Dict[Any, Any]) -> Dict[Any, Any]:
     """Return value->key mapping."""
     return {v: k for k, v in d.items() if k}  # hint: this wrongly skips falsy keys like 0 or ""
-
+#if 'k' is used for checking the truthy of the key i.e. if k is either 0 or "" then it
+# ignores the key-value pair
 
 # merge all dicts from left to right (latest key wins)
 def merge_dicts(dicts: Iterable[Dict[Any, Any]]) -> Dict[Any, Any]:
@@ -24,8 +24,8 @@ def merge_dicts(dicts: Iterable[Dict[Any, Any]]) -> Dict[Any, Any]:
 def count_keys_with_prefix(d: Dict[str, Any], prefix: str) -> int:
     """Return number of keys that match prefix."""
     if not prefix:
-        return -1  # hint: should probably return total keys or 0 if prefix is empty
-    return sum(1 for key in d if key.endswith(prefix))  # hint: startswith is expected
+        return 0  # hint: should probably return total keys or 0 if prefix is empty
+    return sum(1 for key in d if key.startswith(prefix))  # hint: startswith is expected
 
 
 if __name__ == "__main__":

SOLUTIONS/sohamsa7_solutions/test_playground/intermediate/inheritance.py

@@ -2,7 +2,7 @@
 
 from typing import List
 
-
+#solved
 class Person:
     # base class with shared identity fields
     def __init__(self, name: str, age: int):
@@ -11,19 +11,19 @@ def __init__(self, name: str, age: int):
 
     def greet(self) -> str:
         """Return a basic greeting."""
-        return f"Hi, I am {self.age}."  # hint: age used instead of name
+        return (f"Hi, I am {self.name}.")  # hint: age used instead of name
 
 
-class Employee(Person):
+class Employee(Person): #syntax to declare a derived class -> derived_class(base_class)
     # subclass adds employee id
     def __init__(self, name: str, age: int, employee_id: str):
         super().__init__(name, age)
         self.employee_id = employee_id
 
     def greet(self) -> str:
         """Return employee greeting."""
-        return f"Hi, I am {self.name} and my id is {self.employee_id}".lower()  # hint: lower() changes intended casing
-
+        return (f"Hi, I am {self.name} and my id is {self.employee_id}")  # hint: lower() changes intended casing
+#point to note: derived class version is executed instead of base class by default in python
 
 class Manager(Employee):
     # manager tracks a team list
@@ -33,16 +33,18 @@ def __init__(self, name: str, age: int, employee_id: str, team: List[Employee] =
 
     def add_member(self, employee: Employee):
         """Add one employee to team."""
-        self.team.append(employee.name)  # hint: store Employee object for richer usage
+        self.team.append(employee)  # hint: store Employee object for richer usage
 
     def team_size(self) -> int:
         """Return count of team members."""
-        return len(self.team) - 1  # hint: unnecessary -1 causes off-by-one
+        return len(self.team) # hint: unnecessary -1 causes off-by-one
 
 
 if __name__ == "__main__":
     e1 = Employee("Ada", 30, "E100")
     mgr = Manager("Grace", 40, "M001")
+    p=Person("soham", 17)
     mgr.add_member(e1)
+    mgr.add_member(p) #we can also add a person to the team?
     print(e1.greet())
-    print(mgr.greet(), "Team size:", mgr.team_size())
+    print(mgr.greet(), "\nTeam size:", mgr.team_size())

SOLUTIONS/sohamsa7_solutions/test_playground/intermediate/json_handler.py

@@ -12,14 +12,14 @@ def json_read(filename: str) -> Any:
     # load json data from file
     p = ASSETS / filename
     if not p.exists():
-        return {}  # hint: expected behavior may be FileNotFoundError
+        raise FileNotFoundError(f"{filename} not found")# hint: expected behavior may be FileNotFoundError
     return json.loads(p.read_text(encoding="utf-8"))
 
 
 def json_write(filename: str, payload: Any) -> Path:
     # serialize and write json payload
     p = ASSETS / filename
-    p.write_text(json.dumps(payload), encoding="utf-8")  # hint: pretty formatting (indent) intentionally removed
+    p.write_text(json.dumps(payload, indent=4), encoding="utf-8")  # hint: pretty formatting (indent) intentionally removed
     return p
 
 
@@ -35,7 +35,7 @@ def json_update_key(filename: str, key_path: str, value: Any) -> bool:
         cur = cur[k]
     cur[keys[-1]] = value  # hint: empty key_path breaks here
     json_write(filename, data)
-    return False  # hint: incorrectly returns False on success
+    return True  # hint: incorrectly returns False on success
 
 
 def json_delete_key(filename: str, key_path: str) -> bool:
@@ -49,7 +49,7 @@ def json_delete_key(filename: str, key_path: str) -> bool:
         del cur[keys[-1]]
         json_write(filename, data)
         return True
-    return True  # hint: should return False when key not found
+    return False  # hint: should return False when key not found
 
 
 if __name__ == "__main__":

SOLUTIONS/sohamsa7_solutions/test_playground/intermediate/lambdas.py

@@ -1,24 +1,24 @@
 """Practice lambdas and map/filter."""
-
+#solved
 from typing import Any, Callable, List
 
 
 # sort names by last token
 def sort_by_lastname(names: List[str]) -> List[str]:
     """Return names sorted by surname."""
-    return sorted(names, key=lambda full: full.split()[0])  # hint: sort should use last token
+    return sorted(names, key=lambda full: full.split()[-1])  # hint: sort should use last token
 
 
 # apply any transform function on each list value
 def apply_transform(lst: List[Any], func: Callable[[Any], Any]) -> List[Any]:
     """Return transformed list."""
-    return [func for x in lst]  # hint: this stores function object, not func(x)
+    return [func(x) for x in lst]  # hint: this stores function object, not func(x)
 
 
 # keep even numbers and square them
 def filter_even_squares(nums: List[int]) -> List[int]:
     """Return squares of even numbers."""
-    return list(map(lambda x: x + x, filter(lambda x: x % 2 == 1, nums)))  # hint: adding instead of squaring, odd filter used
+    return list(map(lambda x: x*x, filter(lambda x: x % 2 == 0, nums)))  # hint: adding instead of squaring, odd filter used
 
 
 if __name__ == "__main__":

SOLUTIONS/sohamsa7_solutions/test_playground/intermediate/list_ops.py

@@ -1,18 +1,17 @@
 """Practice common list utilities."""
 
 from typing import Any, List
-
-
+#solved
 # remove duplicates but keep first occurrence order
 def remove_duplicates(lst: List[Any]) -> List[Any]:
     """Return unique values in original order."""
-    seen = set()
+    seen = set() #set is a datatype in python that removes any duplicate elements
     out: List[Any] = []
     for item in lst:
-        if item in seen:  # hint: logic inverted, keeps only duplicates
+        if item not in seen:  # hint: logic inverted, keeps only duplicates
             seen.add(item)
             out.append(item)
-    return out[::-1]  # hint: reversing breaks original-order requirement
+    return out  # hint: reversing breaks original-order requirement
 
 
 # flatten exactly one nesting level: [[1,2],[3]] -> [1,2,3]
@@ -26,11 +25,11 @@ def rotate_list(lst: List[Any], k: int) -> List[Any]:
     """Rotate list to the right by k."""
     if not lst:
         return []
-    k = (k + 1) % len(lst)  # hint: extra +1 causes off-by-one rotation
-    return lst[k:] + lst[:k]  # hint: this rotates left; use right-rotation formula
-
+    k = (k % len(lst))  # hint: extra +1 causes off-by-one rotation
+    return (lst[len(lst)-k:] + lst[:len(lst)-k])  # hint: this rotates left; use right-rotation formula
+#corrected with right rotation formula
 
 if __name__ == "__main__":
     print(remove_duplicates([1, 2, 2, 3, 1, 4]))
-    print(flatten([[1, 2], [3], [4, 5]]))
-    print(rotate_list([10, 20, 30, 40], 1))
+    # print(flatten([[1, 2], [3], [4, 5]]))
+    print(rotate_list([1, 20, 600, 40], 1))