Beyond the Basics: Strings

3.1. Beyond the Basics: Strings#

In Python, strings are created using quotes (’’ or “”) and are immutable, while f-strings are formatted strings that allow embedding expressions inside curly braces { } for dynamic value substitution during runtime. Here is a couple of examples for strings:

from math import pi 
import os 

name = "Alice"
age = 25
profession = "engineer"

print (name,age,profession)

Alice 25 engineer

Here is the same example made as a complete sentence using f-strings.

intro = f"My name is {name}, I'm {age} years old, and I work as an {profession}."

print (intro)

My name is Alice, I'm 25 years old, and I work as an engineer.

3.1.1. Formatting numbers#

Python’s f-strings provide a convenient way to format numbers by using the colon character and specifying the desired format. The following table demonstrates a couple of examples with the number \(1\) using f-strings:

Code

Result

1:.2f

1.00

1:.0f

1

1:.10f

1.0000000000

1:%

100.000000%

1:.1%

100.0%

1:e

1.000000e+00

In the example below, the sleep() function from the time module is used to simulate the passage of time and provide a simple demonstration of a progress bar implementation. We define a function simulate_long_running_algorithm() that performs a loop with a sleep of 0.5 seconds between iterations. Within each iteration, the progress of the algorithm is calculated and used to construct a progress bar string. The progress bar consists of a series of equal signs (=) that visually represent the progress, followed by the percentage completion formatted to one decimal defined inside an f-strings.

import time

def simulate_long_running_algorithm():
    total_iterations = 10
    for i in range(total_iterations):
        time.sleep(0.5)  # Simulating processing time
        progress = (i + 1) / total_iterations
        progress_bar = f"[{'=' * int(progress * 20):20s}] {progress * 100:.1f}%"
        print(progress_bar, end='\r')  # Print on the same line
    print("\nAlgorithm complete!")

simulate_long_running_algorithm()

[====================] 100.0%
Algorithm complete!

Escape characters

Escape characters in programming are special characters that are used to represent certain non-printable or special characters within strings. They are typically represented by a backslash (’ \ ‘) followed by a specific character or sequence. We used two escape characters in the previous example, can you identify them?

Code

Result

Description

'

‘

represents the escape sequence for a single quote (‘).

\

\

represents the escape sequence for a backslash (’ \ ‘).

\n

new line

represents the escape sequence for a new line character, which moves the cursor to the beginning of the next line.

\r

carriage return

represents the escape sequence for a carriage return character, which moves the cursor to the beginning of the current line.

\t

tab

represents the escape sequence for a tab character, which adds horizontal spacing.

\b

backspace

represents the escape sequence for a backspace character, which moves the cursor one position back.
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