74 lines
2.3 KiB
Markdown
74 lines
2.3 KiB
Markdown
### **1. `for` Loop with `range()`**
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```python
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for i in range(2, 20, 1):
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print(f"i : {i}", end=" End \n")
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```
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- **`range(start, stop, step)`**: Generates a sequence of numbers starting from `start` (inclusive), up to `stop` (exclusive), increasing by `step`.
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- `range(2, 20, 1)` → numbers from 2 to 19 (inclusive), step 1.
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- **`for` loop**: Iterates over each number in the range.
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- **`print(f"i : {i}", end=" End \n")`**:
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- `f-string`: Formats the output with the current value of `i`.
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- `end=" End \n"`: Replaces the default newline (`\n`) with `" End "` followed by a newline.
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- **Output**: Prints each number with `" End "` at the end of each line.
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---
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### **2. Looping Through a List Using Index and `enumerate()`**
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```python
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list = ['abbas', 'mmd', 2006]
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for key in range(len(list)):
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value = list[key]
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print(key, value)
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```
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- **`len(list)`**: Returns the number of elements in the list (3).
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- **`range(len(list))`**: Creates numbers `0, 1, 2` (indices of the list).
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- **`list[key]`**: Accesses the element at index `key`.
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- **Output**: Prints index and value pair for each element.
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---
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```python
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for key, value in enumerate(list):
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print(key, value)
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```
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- **`enumerate(list)`**: Returns pairs of `(index, value)` for each element.
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- **`key, value`**: Unpacks each pair into two variables.
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- **Output**: Same as above, but more concise and Pythonic.
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> ✅ **Best Practice**: Use `enumerate()` instead of `range(len())` for cleaner code.
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---
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### **3. `zip()` Function – Pairing Two Lists**
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```python
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name = ['egg', 'oil']
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price = [370000, 500000]
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for final in zip(name, price):
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print(final)
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```
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- **`zip(list1, list2)`**: Combines two lists element-wise into tuples.
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- `zip(['egg', 'oil'], [370000, 500000])` → `[('egg', 370000), ('oil', 500000)]`
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- **`for final in zip(...)`**: Iterates over each tuple.
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- **Output**: Prints each pair as a tuple.
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> ✅ Use `zip()` when you need to process multiple lists in parallel.
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---
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### Summary of Key Concepts:
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| Concept | Purpose |
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|----------------|--------|
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| `range(start, stop, step)` | Generate a sequence of numbers |
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| `for` loop | Iterate over a sequence |
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| `len(list)` | Get number of elements |
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| `enumerate()` | Get index and value in a loop |
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| `zip()` | Combine two or more lists element-wise |
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