This tutorial will show you how to convert an

• octal escape sequence to a Python string, and a
• Python string to an octal escape sequence.

But let’s quickly recap what an octal escape sequence is in the first place!

What Is An Octal Escape Sequence?

An Octal Escape Sequence is a backslash followed by 1-3 octal digits (0-7) such as \150 which encodes the ASCII character 'h'. Each octal escape sequence encodes one character (except invalid octal sequence \000). You can chain together multiple octal escape sequences to obtain a word.

Problem Formulation

Question: How to convert an octal escape sequence to a string and vice versa in Python?

Examples

Python Octal to String Built-In Conversion

You don’t need to “convert” an octal escape sequence to a Unicode string if you already have it represented by a bytes object. Python automatically resolves the encoding.

See here:

>>> b'\101\102\103'

b'ABC'

>>> b'101\040\102\040\103'

b'101 B C'

>>> b'\101\040\102\040\103'

b'A B C'

>>> b'\141\142\143'

b'abc'

>>> b'\150\145\154\154\157'

b'hello'

>>> b'\150\145\154\154\157\040\167\157\162\154\144'

b'hello world'

Python Octal to String Explicit Conversion

The bytes.decode('unicode-escape') function converts a given bytes object represented by an (octal) escape sequence to a Python string. For example, br'\101'.decode('unicode-escape') yields the Unicode (string) character 'A'.

def octal_to_string(x): ''' Converts an octal escape sequence to a string''' return x.decode('unicode-escape')

Example: Convert the octal representations presented above:

octals = [br'\101\102\103', br'\101\040\102\040\103', br'\141\142\143', br'\150\145\154\154\157', br'\150\145\154\154\157\040\167\157\162\154\144'] for octal in octals: print(octal_to_string(octal)) 

This leads to the following expected output:

ABC
A B C
abc
hello
hello world

Python String to Octal

To convert a Python string to an octal escape sequence representation, iterate over each character c and convert it to an octal escape sequence using oct(ord©).

The result uses octal representation such as '0o123'. You can do string manipulation, such as slicing and string concatenation, to bring it into the final version '\123', for instance.

Here’s the function that converts string to octal escape sequence format:

def string_to_octal(x): ''' Converts a string to an octal escape sequence''' return '\\' + '\\'.join(oct(ord©)[2:] for c in x)

Background:

• The ord() function takes a character (=string of length one) as an input and returns the Unicode number of this character. For example, ord('a') returns the Unicode number 97. The inverse function of ord() is the chr() function, so chr(ord('a')) returns the original character 'a'.
• The oct() function takes one integer argument and returns an octal string with prefix "0o".

Let’s check how our strings can be converted to the octal escape sequence representation using this function:

strings = ['ABC', 'A B C', 'abc', 'hello', 'hello world'] for s in strings: print(string_to_octal(s))

And here’s the expected output:

\101\102\103
\101\40\102\40\103
\141\142\143
\150\145\154\154\157
\150\145\154\154\157\40\167\157\162\154\144

If you don’t like the one-liner solution provided above, feel free to use this multi-liner instead that may be easier to read:

def string_to_octal(x): ''' Converts a string to an octal escape sequence''' result = '' for c in x: result += '\\' + oct(ord©)[2:] return result

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In this tutorial, we are going to learn how to create a pie chart using JavaScript libraries. We have used Chart.js library for the generating the pie charts. As an alternate option, I have also presented a 3d pie chart example using Google charts library.

Let us see the following examples of creating a pie chart using JavaScript.

• Quick example – Simple pie chart example via ChartJS.
• 3D pie chart with Google Charts library.
• Responsive ChartJS pie chart.

Quick example – Simple pie chart example via ChartJS

<!DOCTYPE html>

<html>

<head>

<title>Chart JS Pie Chart</title>

<link rel='stylesheet' href='style.css' type='text/css' />

</head>

<body> <div class="phppot-container"> <h1>Responsive Pie Chart</h1> <div> <canvas id="pie-chart"></canvas> </div> </div> <script src="https://cdn.jsdelivr.net/npm/chart.js@4.0.1/dist/chart.umd.min.js"></script> <script> new Chart(document.getElementById("pie-chart"), { type : 'pie', data : { labels : [ "Lion", "Horse", "Elephant", "Tiger", "Jaguar" ], datasets : [ { backgroundColor : [ "#51EAEA", "#FCDDB0", "#FF9D76", "#FB3569", "#82CD47" ], data : [ 418, 263, 434, 586, 332 ] } ] }, options : { title : { display : true, text : 'Chart JS Pie Chart Example' } } }); </script>

</body>

</html>

Creating a ChartJS pie chart is a three-step process as shown below.

1. Add the ChartJS library include to the head section of your HTML.
2. Add a canvas element to the HTML.
3. Add the ChartJS class initiation and invoking script before closing the HTML body tag.

About the ChartJS pie chart script

The script sets the following properties to initiate the ChartJS library.

• type – The type of the chart supported by the ChartJS library.
• data – It sets the chart labels and datasets. The dataset contains the data array and the display properties.
• options – It sets the chart title text and its display flag as a boolean true to show it on the browser.

Output:

In a previous tutorial, we have seen the various ways of creating line charts using the Chart JS library.

View Demo

Creating 3D pie chart

There is no option for a 3D pie chart using chart JS. For those users who have landed here looking for a 3D pie chart, you may try Google Charts.

This example uses Google Charts to create a 3D pie chart for a webpage. In a previous code, we use Google Charts to render a bar chart to show students’ attendance statistics.

The Google Charts JavaScript code prepares the array of animal distribution data. This array is for sending it to the chart data table which helps to draw the pie chart.

The Google Charts library accepts the is3D with a boolean true to output a 3D pie chart.

It creates a chart visualization object with the reference with respect to the UI element target. Then, it calls the Google Charts library function to draw and render the chart.

<!DOCTYPE html>

<html>

<head>

<title>3d Pie Chart JavaScript with Google Charts</title>

<link rel='stylesheet' href='style.css' type='text/css' /> <script type="text/javascript" src="https://www.gstatic.com/charts/loader.js"></script>

<script type="text/javascript"> google.charts.load("current", { packages : [ "corechart" ] }); google.charts.setOnLoadCallback(drawChart); function drawChart() { var data = google.visualization.arrayToDataTable([ [ 'Animal', 'Distribution' ], [ 'Horse', 11 ], [ 'Elephant', 2 ], [ 'Tiger', 2 ], [ 'Lion', 2 ], [ 'Jaguar', 7 ] ]); var options = { title : '3d Pie Chart JavaScript with Google Charts', is3D : true, }; var chart = new google.visualization.PieChart(document .getElementById('3d-pie-chart')); chart.draw(data, options); }

</script>

</head>

<body> <div class="phppot-container"> <h1>3d Pie Chart JavaScript with Google Charts</h1> <div id="3d-pie-chart" style="width: 700px; height: 500px;"></div> </div>

</body>

</html>

Responsive pie chart using Chart JS

The Chart JS library provides JavaScript options to make the output pie chart responsive.

This example script uses those options to render a responsive pie chart in a browser.

The JavaScript code to render a responsive pie chart is the same as we have seen in the quick example above.

The difference is nothing but to set responsive: true in the ChartJS options properties.

If you want to create a responsive chart using Google Charts, then the linked article has an example.

<!DOCTYPE html>

<html>

<head>

<title>Responsive Pie Chart</title>

<link rel='stylesheet' href='style.css' type='text/css' />

<meta name="viewport" content="width=device-width, initial-scale=1">

</head>

<body> <div class="phppot-container"> <h1>Responsive Pie Chart</h1> <div> <canvas id="pie-chart"></canvas> </div> </div> <script src="https://cdn.jsdelivr.net/npm/chart.js@4.0.1/dist/chart.umd.min.js"></script> <script> new Chart(document.getElementById("pie-chart"), { type : 'pie', data : { labels : [ "Lion", "Horse", "Elephant", "Tiger", "Jaguar" ], datasets : [ { backgroundColor : [ "#51EAEA", "#FCDDB0", "#FF9D76", "#FB3569", "#82CD47" ], data : [ 418, 263, 434, 586, 332 ] } ] }, options : { title : { display : true, text : 'Responsive Pie Chart' }, responsive : true } }); </script>

</body>

</html>

View DemoDownload

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Summary: The most efficient way to split a string using variable spaces is to use the split function like so given_string.split(). An alternate approach is to use different functions of the regex package to split the string at multiple whitespaces.

Minimal Example

text = "a b c d"

# Method 1

print(text.split())

# Method 2

import re

print(re.split('\s+', text))

# Method 3

print([x for x in re.findall(r'\S+', text) if x != ''])

# Method 4

print(re.sub(r'\s+', ',', text).split(','))

# Method 5

print(list(filter(None, text.split()))) # ['a', 'b', 'c', 'd']

Problem Formulation

Problem: Given a string. How will you split the string using multiple spaces?

Example

# Input

text = "abc xyz lmn pqr"

# Output

['abc', 'xyz', 'lmn', 'pqr']

The given input has multiple spaces between each substring, i.e., there are three spaces after abc, two spaces after xyz while a single space after lmn. So, not only do you have multiple spaces between the substring but also varied number of spaces. Can you split the string by varied and multiple spaces?

Though the question might look daunting at first but once you get hold of it, the solutions to this problem are easier than one can imagine. So, without further delay let us dive into the different ways of solving the given problem.

Method 1: Using split()

The built-in split('sep') function allows you to split a string in Python based on a given delimiter. By default the split function splits a given string at whitespaces. Meaning, if you do not pass any delimiter to the split function then the string will be split at whitespaces.

You can use this default property of the split function and successfully split the given string at multiple spaces just by using the split() function.

Code:

text = "abc xyz lmn pqr"

print(text.split()) # ['abc', 'xyz', 'lmn', 'pqr']

Recommended Digest: Python String split()

Method 2: Using re.split

The re.split(pattern, string) method matches all occurrences of the pattern in the string and divides the string along the matches resulting in a list of strings between the matches. For example, re.split('a', 'bbabbbab') results in the list of strings ['bb', 'bbb', 'b'].

Approach: To split the string using multiple space characters use re.split("\s+", text) where \s+ is the matching pattern and it represents a special sequence that returns a match whenever it finds any whitespace character and splits the string. So, whenever there’s a space or multiple spaces (any number of occurrences of space are whitespace characters) the string will be split.

Code:

import re

text = "abc xyz lmn pqr"

print(re.split('\s+', text))

# ['abc', 'xyz', 'lmn', 'pqr']

Recommended Read:  Python Regex Split.

Method 3: Using re.findall

The re.findall(pattern, string) method scans the string from left to right, searching for all non-overlapping matches of the pattern. It returns a list of strings in the matching order when scanning the string from left to right.

Recommended Read: Python re.findall() – Everything You Need to Know

Code:

import re

text = "abc xyz lmn pqr"

print([x for x in re.findall(r'\S+', text) if x != ''])

# ['abc', 'xyz', 'lmn', 'pqr']

Method 4: Using re.sub

The regex function re.sub(P, R, S) replaces all occurrences of the pattern P with the replacement R in string S. It returns a new string. For example, if you call re.sub('a', 'b', 'aabb'), the result will be the new string 'bbbb' with all characters 'a' replaced by 'b'.

Approach: Use the re.sub method to replace all occurrences of space characters in the given string with a comma. Thus, the string will now have commas instead of space characters and you can simply split it using a normal string split method by passing comma as the delimiter.

Silly! Isn’t it? Nevertheless, it works.

Code:

import re

text = "abc xyz lmn pqr"

res = re.sub(r'\s+', ',', text).split(',')

print(res)

# ['abc', 'xyz', 'lmn', 'pqr']

Method 5: Using filter

Python’s built-in filter() function filters out the elements that pass a filtering condition. It takes two arguments: function and iterable. The function assigns a Boolean value to each element in the iterable to check whether the element will pass the filter or not. It returns an iterator with the elements that pass the filtering condition.

Related Read: Python filter()

Approach: You can use the filter() method to split the string by space. Feed in None as the first argument and the list of split strings as the second argument into the filter function. The filter() function then iterates through the list and filters out the spaces from the given string and returns only the non-whitespace characters. As the filter() method returns an object, we need to use the list() to convert the object into a list.

Code:

text = "abc xyz lmn pqr"

print(list(filter(None, text.split())))

# ['abc', 'xyz', 'lmn', 'pqr']

Conclusion

Hurrah! We have successfully solved the given problem using as many as five different ways. I hope you enjoyed reading this article and it helped you in your Python coding journey. Please subscribe and stay tuned for more interesting articles!

Happy coding!

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