Description
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Objective
Practice Git, Java and Eclipse.
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Marking
This exercise will be autotested out of of 10 marks.
It is worth 2% of your nal grade.
The submission deadline is January 22, 2017 11:59pm on GitHub.
This is an individual assignment.
Late submission policy: No late submissions are accepted.
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How to submit your work
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Please sign in to git using your mail.utoronto.ca account. Use this invitiation link https://classroom.github.com/assignment-invitations/9c3bb8ad2850e234f9085fb1f338c852 and clone the starter code following GitHub instructions.
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Complete the code for countBlob() method.
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You may test your work using BlobApp.
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To submit your work, add, commit and push your changes to your repository.
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Do not commit the les and directories generated by Eclipse, such as bin, doc, .project, etc. Marks will be deducted if you submit these.
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The date and time of your last commit must be on or before 22 Jan 2017, 11:59pm.
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What is a Blob?
In this section we explain what are blobs, how to generate a grid of them, and how to count them. This problem is often encountered in image processing. We consider an image as a rectangle made of pixels, where each pixel is turned on or o , that is each pixel can be black or white. We will model such an image by a grid a characters, where a black pixel is indicated by the presence of letter X in the approriate position, and a white pixel is indicated by the presence of a dot in the relevant position. An important problem in image processing is identifying and labelling connected component of pixels, or blobs.
By de nition, a blob is a contiguous collection of X’s. For example, the grid below contains four di erent blobs which have been outlined.
CSC301 Introduction To Software Engineering (
Our goal is to create an application that given a grid, counts and reports the number of blobs. In order to enable you to test, we have provided in the starter code a blob generator.
We have represented a grid internally as a two-dimensional array of boolean values, with true indicating a blob character, and false indicating a non-blob character
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Counting Blobs
In order to successfully count blobs, let’s make the following observations:
A single X character surrounded by non-blob characters is a blob, and, if we have a blob larger than one character, removing a blob character, what remains is again a blob. (What kind of de nition is this?)
Once we have identi ed all characters that do belong to a particular blob, we want to mark them so they do not get counted twice.
A possible solution is to maintain a grid of the same size as the original grid, tentatively called marked, which is going to be used to mark individual cells of the original grid if and only if:
The location does exist; that is it is not outside the boundaries of the grid. The location does contain a blob character.
The location has not already been visited.
Please complete the code for the countBlob() method as required in the starter code.
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