humidity of the maximum information gain is selected.(7) The same can be done by:(8) Cool corresponds to a subset of data is no, so directly write no, no need to split. Mild corresponding subset of data, humidity and windy information gain is the same, because in this group, the ratio of the yes tuple is larger than the no tuple, so write directly yes, the resulting decision tree graph:However, the use of
you.
This girl's decision-making process is a typical classification tree decision. It is equivalent to dividing men into two categories by age, appearance, income, and whether or not civil servants: Seeing and seeing. Assume that the girl's requirement for a man is: A civil servant who is under 30 years old, looks medium and above, and is a high-income or above
partitioning dataset to divide the data set to create a branch node for each subset of partitions Call the function createbranch () and increase the return result to the branch node in the Return branch node Once we have constructed a decision tree model, it i
need to overlap, and the current node location is determined by using 2(0.5, 1.0).
Summary: Use this to gradually increasexAxis coordinates and gradually decreaseyThe coordinate of the axis can well take into account the number and depth of leaf nodes of the tree, so the logical proportion of the graph is well determined, even if the image size changes, we can still see the scaled tree chart.
Ii. Use
first field of a list object # @reverse =true descending sort, by default ascending sort Sortedclasscount=sorted (Classcount.items, key=operator.itemgetter (1), reverse=true) #返回出现次数最多的类标签 return sortedclasscount[0][0]Well, with this in mind, we can write the decision tree's build code recursively.#创建树def Createtree (dataset,labels): #获取数据集中的最后一列的类标签, deposit classlist list classlist=[example
benefit. The problem is that when the sample size is low, I'm not slow at all. So this value is generally lazy to ignore it.
In addition to these parameters to be noted, other points of attention during the tuning are:1) When the sample number is small but the sample features are very large, the decision tree is easy to fit, in general, more samples than the number of features will be relatively e
Decision tree is a method for in-depth analysis of classification issues. In actual problems, decision trees generated by algorithms are often complex and huge, making it hard for users to understand. This tells us that we should strengthen the research on Tree Pruning while precision of multiclass classification. This
1. Introduction to the algorithm backgroundThe classification tree (decision tree) is a very common classification method. He is a kind of supervised learning, so-called regulatory learning is simple, that is, given a bunch of samples, each sample has a set of attributes and a category, these categories are predetermined, then by learning to get a classifier, the
constructed by using the known multivariable data, and a variable is predicted according to the other variable values. In the classification, people tend to measure a certain object first, then use certain classification criteria to determine the category of the object belonging to it. For example, given the identification characteristics of a fossil, it is predicted that the fossil belongs to that branch, that genus, or even that one. Another
the different values, the corresponding category labels are pure, the decision-maker will certainly choose this feature, as the identification of unknown data criteria. The following formula for calculating the gain of information can be found at this time the corresponding information gain is the largest.G (D,a) =h (D)-H (d| AG (D,a): Represents the information gain of feature A on training data set DH (d): Empirical entropy representing data set DH
Course Address: Https://class.coursera.org/ntumltwo-002/lecture Important! Important! Important ~ I. Decision trees (decision tree), Pocket (Bagging), Adaptive Enhancement (AdaBoost)
When the bagging and AdaBoost algorithms are reclassified, it is time for all weak classifiers to function simultaneously. The difference between them is whether each w
example.
This figure can basically be regarded as a decision tree, saying that it is "basically measurable" because the judgment conditions in the figure are not quantified, such as income in high school and low school, and so on. It cannot be regarded as a decision tree in
Copyright Notice:This article was published by Leftnoteasy on http://leftnoteasy.cnblogs.com , this article can be reproduced or partially used, but please indicate the source, if there is a problem, please contact [email protected]Objective:Decision tree This algorithm has many good characteristics, for example, the training time complexity is low, the prediction process is relatively fast, the model is ea
Copyright Notice:This article is published by Leftnoteasy in Http://leftnoteasy.cnblogs.com, this article can be reproduced or part of the use, but please indicate the source, if there is a problem, please contact [email protected]. can also add my Weibo: @leftnoteasyObjective:Decision tree This algorithm has many good characteristics, for example, the training time complexity is low, the prediction process
Preface:
The decision tree algorithm has many good features, such as low training time complexity, fast prediction process, and easy model display (easy to make the decision tree into images. But at the same time, there are some bad aspects of a single decision
you.
This girl's decision-making process is a typical classification tree decision. It is equivalent to dividing men into two categories by age, appearance, income, and whether or not civil servants: Seeing and seeing. Assume that the girl's requirements for men are: civil servants under the age of 30, who are of medium or higher sizes and are high-income or abo
characteristics of the learning, so that the classification is not allowed, for example, a special feature as a category of judging criteria, so that does not have a particular attribute of the data into this category. This is called fitting, English is called overfitting literal translation is over-matching, that is, matching is too thin, a bit too. To solve this problem, it is necessary to simplify the decision
) of set D) difference from empirical Conditional Entropy H (d | A) given by feature:
3) information gain rate
The information gain value is relative to the training set, and has no absolute significance.
For example, a train can speed up from 10 Mb/s to 100 Mb/s within 9 s, but now a motorcycle can speed up from 1 MB/s to 11 Mb/s within 1 s, although the speed of a motorcycle is not as high as that of a train after acceleration, it has the same acce
: Where ,, the probability that a category appears in the sample. 2. Information Gain refers to the change of entropy before and after division. It can be expressed by the following formula: In this formula, it represents the attributes of the sample and a set of values of all attributes. Yes, one of the attribute values is a sample set of values in. Iv. Experiment Simulation 1. data preprocessing the following data is used as an example to implement
the logical ratio of the graph is very good to determine, even if the image size changes, we can still see proportionally drawn tree chart.Two. Use decision trees to predict contact lens typesHere is an example of using decision trees to predict the type of contact lenses a patient needs to wear. Here are the general
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