Enhanced the code

[priyaa-rawat]

Describe your change:

Added an exception and a new method.

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

Checklist:

• [x ] I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• [ x] I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• [x ] All filenames are in all lowercase characters with no spaces or dashes.
• [ x] All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
• All new algorithms have a URL in its comments that points to Wikipedia or other similar explanation.
• If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.
  Hacktoberfest 2021 - Implement algorithms or data structures, fix existing ones and more! #4996 Update: graph_matrix #5318 @cclauss

[cclauss]

Under the Details next to the ❌ below, psf/black say:

-        if u>self.vertex or v>self.vertex or u<1 or v<1:
+        if u > self.vertex or v > self.vertex or u < 1 or v < 1:

so please add spaces to let your code breathe. As discussed in CONTRIBUTING.md, code that is not black formatted will not be accepted.

[priyaa-rawat]

@cclauss I did the changes and formatted the code with black too. I hope there won't be any other errors. Since Iam a beginner Iam not able to get them. Thanku for the guidance .

[priyaa-rawat]

@poyea @cclaus please review my PR

[cclauss]

So… There are no doctests or type hints as discussed in CONTRIBUTING.md. This code confuses two kinds of graphs.

Vertex and show() refer to an x, y chart that is plotted. In this sense, vertex is misnamed and should be named size or dimension as it represents the maximum value for x and/or y.

The rest of the code is focused on a graph that is a set of nodes connected by edges. This can be proven by looking at the output of .show().

Which of these two graphs should we focus on?!?

[priyaa-rawat]

@cclaus I went through all the algorithms and files and this one code had no doctests or type hints originally like most of the files in the folder so I didnt to avoid any errors.
-As for the variable vertex and .show it was how the code was from the beginning so I didn't alter it though it was confusing to me too.

I just added a function remove edge and an if condition to raise an error if the index goes out of range.

-This code is supposed to focus on nodes and edges according to what I understood.

[cclauss]

All files that start with b (i.e. graphs/b*.py) have doctests.