TE1 10 Vivek Chaurasia C1 EXP5 qwerty qwwe PDF

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Machine learning is an application of artificial intelligence (AI) that provides systems the ability to automatically learn and improve from experience without being explicitly programmed. Machine learning focuses on the development of computer programs that can access data and use it to learn for t...

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Name: VIVEK CHAURASIA

Class: TE-1

Roll No: 10

Batch: C1

EXPERIMENT NO: 5 AIM: Implementation of Clustering algorithm ( K-means/Agglomerative ) OBJECTIVE: To learn how to classify data by K means algorithm for classification THEORY: Clustering is one of the most common the structure of the data. It can be defined as the task of identifying subgroups in the data such that data points in the same subgroup (cluster) are very similar clusters are very different. In other words, we try to find homogeneous subgroups within the data such that data points in each cluster are as similar as possible according to a similarity measure such as Euclidean-based which similarity measure to use is application Clustering is considered an unsupervised learning method. Kmeans is considered as one of the most used clustering algorithms due to its simplicity. It is an iterative algorithm that tries to partition the dataset into K overlapping subgroups (clusters iterating until there is no change to the centroids. i.e assign changing. It tries to make the intracluster data points as similar as possible while also keeping the clusters as different (far) as possible. It assigns data points to a cluster such that the sum of the squared distance between the data points and the cluster’s centroid (arithmetic data points that belong to that cluster) is at the minimum. The less variation we have within clusters, the more homogeneous (similar) the data points are within the same cluster. ALGORITHM: The way kmeans algorithm works is as foll 1. Specify number of clusters 2. Initialize centroids by first shuffling the dataset and then randomly selecting for the centroids without replacement. 3. Keep iterating until there is no change to the centroids. i.e assignment of data points clusters isn’t changing. 4. Compute the sum of the squared distance between data points and all centroids. 5. Assign each data point to the closest cluster (centroid).

6. Compute the centroids for the clusters by taking the average of the all data points that belong to each cluster.

The objective function is:

The working of the K-Means algorithm is explained in the below steps: Step-1: Select the number K to decide the number of clusters. Step-2: Select random K points or centroids. (It can be other from the input dataset). Step-3: Assign each data point to their closest centroid, which will form the predefined K clusters. Step-4: Calculate the variance and place a new centroid of each cluster. Step-5: Repeat the third steps, which means reassign each datapoint to the new closest centroid of each cluster. Step-6: If any reassignment occurs, then go to step 4 else go to FINISH.

Step-7: The model is ready.

Let's consider the visual plots: Suppose we have two variables M1 and M2. The x given below:

• Let's take number k of clusters, i.e., K=2, to identify the dataset and to put them into different clusters. It means here we will try to • We need to choose some random k points or centroid to form the cluster. These points can be either the points from the dataset or any other point. So, here we are selecting the below two points as k points, which are not the part of our dataset. Consider the below image:

Now we will assign each data point of the scatter plot to its closest K will compute it by applying some mathematics that we have studied to calculate the distance between two points. So, we will draw a median between both the below image:

From the above image, it is clear that points left side of the line is near to the K1 or blue centroid, and points to the right of the line are close to blue and yellow for clear visualization.

As we need to find the closest cluster, so we will repeat the process by choosing centroid. To choose the new centroids, we will compute the center of gravity of thes centroids, and will find new centroids as below:

As we got the new centroids so again will draw the median line and reassign the data points. So, the image will be:

We can see in the above image; there are no dissimilar data points on either side of the line, which means our model is formed. Consider the below image:

As our model is ready, so we can now remove the assumed centroids, and the two final clusters will be as shown in the below image:

APPLICATION: kmeans algorithm is very popular and used in a variety of applications such as market segmentation, document clustering, image segmentation and image compression, etc. CODE AND OUTPUT:

CONCLUSION: K- means clustering is simplest method used for forming data clusters...