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Improve advanced string manipulation section
- Briefly explained methods of objects in the context of strings - Revised each subsection for better readability - Added a few examples demonstrating exceptions in the context of string manipulation - Modified slide types containing notes to 'skip' for student notebook generation (also outside of string manipulation, but not in classes as it's moved to the end in another issue)
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‎Intermediate.ipynb‎

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@@ -4749,6 +4749,62 @@
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"# <ins>8.</ins> Advanced string manipulation"
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]
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},
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{
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"cell_type": "markdown",
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"id": "e34aedb6",
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"metadata": {
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"editable": false,
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"slideshow": {
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"slide_type": "slide"
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},
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"tags": []
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},
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"source": [
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"## String Methods - Working with String Objects"
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]
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},
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{
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"cell_type": "markdown",
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"id": "ffef8f84",
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"metadata": {
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"editable": false,
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"slideshow": {
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"slide_type": ""
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}
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},
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"source": [
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"In Python, strings are objects, and objects have **methods** - functions that belong to and operate on that object.\n",
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"\n",
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"**Syntax**: `string_object.method_name(arguments)`\n",
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"\n",
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"Key characteristics:\n",
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"- Methods are called using _dot notation_: `variable.method()`\n",
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"- String methods return a **new string** (strings are immutable)\n",
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"- The original string is never modified\n",
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"- You must assign the result if you want to keep it\n",
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"\n",
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"**Example:**"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"id": "d5bd4280",
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"metadata": {
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"editable": true,
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"slideshow": {
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"slide_type": ""
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},
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"tags": []
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},
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"outputs": [],
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"source": [
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"text = \"hello world\"\n",
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"result = text.upper() # Creates new string\n",
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"print(text) # Still \"hello world\" \n",
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"print(result) # \"HELLO WORLD\""
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]
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},
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{
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"cell_type": "markdown",
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"id": "c9016a2e-dee1-4030-a1a0-8e519a84be6f",
@@ -4760,10 +4816,11 @@
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"tags": []
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},
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"source": [
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"* Adjusting case\n",
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"* Formatting strings\n",
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" - _Note_: Modification requires assignment, because these functions return a copy, not modifying the original string\n",
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"* Quering the existence, replacing, splitting"
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"Common categories of string methods we'll explore:\n",
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"- **Finding/searching**: `find()`, `index()`\n",
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"- **Checking**: `startswith()`, `endswith()`\n",
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"- **Transforming**: `replace()`, `upper()`, `lower()`, `capitalize()`, `strip()`\n",
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"- **Splitting/joining**: `split()`, `join()`"
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]
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},
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{
@@ -4777,10 +4834,22 @@
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"tags": []
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},
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"source": [
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"## Finding values \n",
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"* `find()` and `index()` both return index of a substring,\n",
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" - `index()` raises a `ValueError` exception when not found (_exception handling_)\n",
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" - `find()` returns `-1` when a values was not found\n"
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"## Finding/searching string methods"
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]
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},
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{
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"cell_type": "markdown",
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"id": "a4fa9b5b",
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"metadata": {
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"editable": false,
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"slideshow": {
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"slide_type": ""
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}
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},
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"source": [
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"These methods help you locate substrings within a string, returning their position or checking for their presence:\n",
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"* `index()` - returns `-1` if the substring is not found\n",
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"* `find()` - raises a `ValueError` if the substring is not found"
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]
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},
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{
@@ -4817,6 +4886,19 @@
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"print(line.find('wombat'))"
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]
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},
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{
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"cell_type": "markdown",
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"id": "714fc569",
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"metadata": {
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"editable": false,
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"slideshow": {
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"slide_type": ""
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}
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},
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"source": [
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"The key difference is how they handle missing substrings - `find()` returns `-1` while `index()` raises an exception:"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
@@ -4847,7 +4929,7 @@
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"tags": []
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},
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"source": [
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"## Checking conditions on strings"
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"## Checking string methods"
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]
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},
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{
@@ -4861,7 +4943,9 @@
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"tags": []
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},
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"source": [
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"* Checking whether a string starts or ends a certain way is really common and easy"
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"These methods return boolean values (`True` or `False`) to verify if a string matches certain patterns or criteria:\n",
4947+
"* `startswith(substring)`\n",
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"* `endswith(substring)`"
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]
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},
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{
@@ -4908,12 +4992,12 @@
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"metadata": {
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"editable": false,
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"slideshow": {
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"slide_type": "slide"
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"slide_type": ""
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},
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"tags": []
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},
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"source": [
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"* The canonical way to search a string (if not interested in the index):"
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"The canonical way to search a string (if not interested in the index):"
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]
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},
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{
@@ -4944,7 +5028,25 @@
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"tags": []
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},
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"source": [
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"## Replacing a value:"
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"## Transforming string methods"
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]
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},
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{
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"cell_type": "markdown",
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"id": "80b12b8b",
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"metadata": {
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"editable": false,
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"slideshow": {
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"slide_type": ""
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}
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},
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"source": [
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"These methods create modified versions of strings by replacing content, changing case, or removing unwanted characters. _**Remember**: strings are immutable, so these methods always return a new string._\n",
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"* `replace(old, new)`\n",
5046+
"* `upper()`\n",
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"* `lower()`\n",
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"* `capitalize()`\n",
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"* `strip()`"
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]
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},
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{
@@ -4966,23 +5068,29 @@
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]
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},
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{
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"cell_type": "markdown",
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"id": "bb4faee5-8c3f-4919-acbe-1b7b2cf7b700",
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"cell_type": "code",
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"execution_count": null,
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"id": "a95784ad-44fc-4e7c-9b16-caa09fedbc60",
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"metadata": {
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"editable": false,
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"editable": true,
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"slideshow": {
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"slide_type": "slide"
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"slide_type": ""
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},
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"tags": []
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},
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"outputs": [],
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"source": [
4979-
"## Bring all words to a common case"
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"arc_update = \"ThE HAmILton suPERcompUTER is beiNg UPGraded\"\n",
5084+
"print(arc_update)\n",
5085+
"print(arc_update.upper())\n",
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"print(arc_update.title())\n",
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"print(arc_update.capitalize())"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"id": "a95784ad-44fc-4e7c-9b16-caa09fedbc60",
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"id": "22763b5f-7576-43c5-a237-925dce9b88aa",
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"metadata": {
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"editable": true,
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"slideshow": {
@@ -4992,44 +5100,63 @@
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},
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"outputs": [],
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"source": [
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"arc_update = \"ThE HAmILton suPERcompUTER is beiNg UPGraded\"\n",
4996-
"print(arc_update)\n",
4997-
"print(arc_update.upper())\n",
4998-
"print(arc_update.title())\n",
4999-
"print(arc_update.capitalize())"
5103+
"user_input = \" [email protected] \"\n",
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"email = user_input.strip()\n",
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"print(f\"Original: '{user_input}'\")\n",
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"print(f\"Cleaned: '{email}'\")"
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]
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},
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{
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"cell_type": "markdown",
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"id": "7a25cc7f-6040-4c03-ac38-b5f9a7baef41",
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"id": "2fd63835",
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"metadata": {
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"editable": false,
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"slideshow": {
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"slide_type": "slide"
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},
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"tags": []
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}
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},
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"source": [
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"## Removing white space"
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"These methods work with any string and don't raise exceptions, but you may want to validate the results."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"id": "22763b5f-7576-43c5-a237-925dce9b88aa",
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"metadata": {
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"editable": true,
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"slideshow": {
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"slide_type": ""
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},
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"tags": []
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},
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"id": "8f1ceba1",
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"metadata": {},
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"outputs": [],
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"source": [
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"user_input = \" [email protected] \"\n",
5030-
"email = user_input.strip()\n",
5031-
"print(f\"Original: '{user_input}'\")\n",
5032-
"print(f\"Cleaned: '{email}'\")"
5129+
"# Transforming methods don't raise exceptions, but you can validate transformed results\n",
5130+
"def process_username(username):\n",
5131+
" \"\"\"Process and validate a username.\"\"\"\n",
5132+
" if not isinstance(username, str):\n",
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" raise TypeError(f\"Username must be a string, got {type(username).__name__}\")\n",
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" \n",
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" # Transform: strip whitespace and convert to lowercase\n",
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" processed = username.strip().lower()\n",
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" \n",
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" # Validate the result\n",
5139+
" if not processed:\n",
5140+
" raise ValueError(\"Username cannot be empty after processing\")\n",
5141+
" \n",
5142+
" if len(processed) < 3:\n",
5143+
" raise ValueError(f\"Username must be at least 3 characters, got {len(processed)}\")\n",
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" \n",
5145+
" return processed\n",
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"\n",
5147+
"# Valid case\n",
5148+
"try:\n",
5149+
" result = process_username(\" JohnDoe \")\n",
5150+
" print(f\"\u2713 Processed username: '{result}'\")\n",
5151+
"except ValueError as e:\n",
5152+
" print(f\"Error: {e}\")\n",
5153+
"\n",
5154+
"# Invalid case\n",
5155+
"try:\n",
5156+
" result = process_username(\" AB \")\n",
5157+
" print(f\"\u2713 Processed username: '{result}'\")\n",
5158+
"except ValueError as e:\n",
5159+
" print(f\"Error: {e}\")"
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]
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},
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{
@@ -5043,7 +5170,22 @@
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"tags": []
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},
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"source": [
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"## Extracting/concatenating the individual words or parts"
5173+
"## Splitting/joining string methods"
5174+
]
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},
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{
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"cell_type": "markdown",
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"id": "71a4546c",
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"metadata": {
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"editable": false,
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"slideshow": {
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"slide_type": ""
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}
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},
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"source": [
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"These methods allow you to break strings apart into lists of substrings, or combine lists of strings into a single string. They're particularly useful for parsing text data or formatting output:\n",
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"* `split(separator)` - splits string into a list at each occurrence of separator (defaults to whitespace)\n",
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"* `join(iterable)` - joins elements of an iterable into a single string with the string as separator"
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]
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},
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{
@@ -5079,7 +5221,7 @@
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"tags": []
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},
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"source": [
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"The operation in the other direction is `a_string.join()` where `a_string` is placed between every string of a list"
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"The `join` operation is `a_string.join()` where `a_string` is placed between every string of a list"
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]
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},
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{
@@ -5116,6 +5258,40 @@
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"print(\"\\n\".join(line_list))"
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]
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},
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{
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"cell_type": "markdown",
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"id": "0deaf239",
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"metadata": {
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"editable": false,
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"slideshow": {
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"slide_type": ""
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}
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},
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"source": [
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"`join()` will raise a `TypeError` if the iterable contains non-string elements"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"id": "225bdd40",
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"metadata": {
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"editable": true,
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"slideshow": {
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"slide_type": ""
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},
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"tags": []
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},
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"outputs": [],
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"source": [
5287+
"flags = [16384,1048576]\n",
5288+
"\n",
5289+
"for i in range(len(flags)):\n",
5290+
" flags_str = \"+\".join(flags[i])\n",
5291+
"#flags_str = \"+\".join(str(flag) for flag in flags)\n",
5292+
"#print(flags_str)"
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]
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},
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{
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"cell_type": "markdown",
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"id": "a965b5d9-59f4-4ed5-b7e9-89f5f0bcf60f",
@@ -5932,7 +6108,7 @@
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython3",
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"version": "3.11.5"
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"version": "3.13.0"
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}
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},
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"nbformat": 4,

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