﻿ Python Bisect: Find the first occurrence of a given number in a sorted list using Binary Search - w3resource

# Python Bisect: Find the first occurrence of a given number in a sorted list using Binary Search

## Python Bisect: Exercise-4 with Solution

Write a Python program to find the first occurrence of a given number in a sorted list using Binary Search (bisect).

Sample Solution:

Python Code:

``````from bisect import bisect_left
def Binary_Search(a, x):
i = bisect_left(a, x)
if i != len(a) and a[i] == x:
return i
else:
return -1

nums = [1, 2, 3, 4, 8, 8, 10, 12]
x = 8
num_position = Binary_Search(nums, x)
if num_position == -1:
print(x, "is not present.")
else:
print("First occurrence of", x, "is present at index", num_position)
```
```

Sample Output:

```First occurrence of 8 is present at index 4
```

Flowchart:

## Visualize Python code execution:

The following tool visualize what the computer is doing step-by-step as it executes the said program:

Python Code Editor:

Next: Write a Python program to find the index position of the largest value smaller than a given number in a sorted list using Binary Search (bisect).

What is the difficulty level of this exercise?

Test your Programming skills with w3resource's quiz.

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## Python: Tips of the Day

How to make a chain of function decorators?

```from functools import wraps

def makebold(fn):
@wraps(fn)
def wrapped(*args, **kwargs):
return "<b>" + fn(*args, **kwargs) + "</b>"
return wrapped

def makeitalic(fn):
@wraps(fn)
def wrapped(*args, **kwargs):
return "<i>" + fn(*args, **kwargs) + "</i>"
return wrapped

@makebold
@makeitalic
def hello():
return "hello world"

@makebold
@makeitalic
def log(s):
return s

print hello()        # returns "<b><i>hello world</i></b>"
print hello.__name__ # with functools.wraps() this returns "hello"
print log('hello')   # returns "<b><i>hello</i></b>"
```

Ref: https://bit.ly/3cVz5iw