通常，在分类中，您有一组预定义的类，并希望知道新对象属于哪个类。

聚类尝试将一组对象分组，并发现对象之间是否存在某种关系。

在机器学习的背景下，分类是监督学习，聚类是无监督学习。

也可以看看维基百科上的分类和聚类。

通常，在分类中，您有一组预定义的类，并希望知道新对象属于哪个类。

聚类尝试将一组对象分组，并发现对象之间是否存在某种关系。

在机器学习的背景下，分类是监督学习，聚类是无监督学习。

也可以看看维基百科上的分类和聚类。

There are two definitions in data mining "Supervised" and "Unsupervised". When someone tells the computer, algorithm, code, ... that this thing is like an apple and that thing is like an orange, this is supervised learning and using supervised learning (like tags for each sample in a data set) for classifying the data, you'll get classification. But on the other hand if you let the computer find out what is what and differentiate between features of the given data set, in fact learning unsupervised, for classifying the data set this would be called clustering. In this case data that are fed to the algorithm don't have tags and the algorithm should find out different classes.

首先，像这里的许多回答一样:分类是有监督的学习，聚类是无监督的。这意味着:

Classification needs labeled data so the classifiers can be trained on this data, and after that start classifying new unseen data based on what he knows. Unsupervised learning like clustering does not uses labeled data, and what it actually does is to discover intrinsic structures in the data like groups. Another difference between both techniques (related to the previous one), is the fact that classification is a form of discrete regression problem where the output is a categorical dependent variable. Whereas clustering's output yields a set of subsets called groups. The way to evaluate these two models is also different for the same reason: in classification you often have to check for the precision and recall, things like overfitting and underfitting, etc. Those things will tell you how good is the model. But in clustering you usually need the vision of and expert to interpret what you find, because you don't know what type of structure you have (type of group or cluster). That's why clustering belongs to exploratory data analysis. Finally, i would say that applications are the main difference between both. Classification as the word says, is used to discriminate instances that belong to a class or another, for example a man or a woman, a cat or a dog, etc. Clustering is often used in the diagnosis of medical illness, discovery of patterns, etc.

通过聚类，可以用所需的属性(如数量、形状和提取的聚类的其他属性)对数据进行分组。而在分类中，组的数量和形状是固定的。 大多数聚类算法都给出了聚类个数作为参数。然而，有一些方法可以找出合适的集群数量。

聚类的目的是在数据中找到组。“集群”是一个直观的概念，确实如此 没有严格的数学定义。一个集群的成员应该是 彼此相似，而与其他集群的成员不同。一个集群 算法对一个未标记的数据集Z进行操作，并在其上生成一个分区。

对于类和类标签， 类包含相似的对象，而来自不同类的对象 是不同的。有些类具有明确的含义，在最简单的情况下 相互排斥。例如，在签名验证中，签名为任意一种 真的或伪造的。真正的阶级是两者之一，不管我们可能不是 能根据观察到的特定特征正确猜测的。