Random Forest Vs Decision Tree: Exploring Key Differences

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What is Decision Tree 

Decision Tree is a supervised learning algorithm used in machine learning. It operated in both classification and regression algorithms. As the name suggests, it is like a tree with nodes. The branches depend on the number of criteria. It splits data into branches like these till it achieves a threshold unit. A decision tree has root nodes, children nodes, and leaf nodes.

Recursion is used for traversing through the nodes. You need no other algorithm. It handles data accurately and works best for a linear pattern. It handles large data easily and takes less time.

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Decision Tree is a supervised learning algorithm used in machine learning. It operated in both classification and regression algorithms. As the name suggests, it is like a tree with nodes. The branches depend on the number of criteria. It splits data into branches like these till it achieves a threshold unit. A decision tree has root nodes, children nodes, and leaf nodes.

Recursion is used for traversing through the nodes. You need no other algorithm. It handles data accurately and works best for a linear pattern. It handles large data easily and takes less time.

How does it work?

1. Splitting

Data, when provided to the decision tree, undergoes splitting into various categories under branches. 

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2. Pruning

Pruning is shredding of those branches furthermore. It works as a classification to subsidize the data in a better way. Like, the same way we say pruning of excess parts, it works the same. The leaf node is reached, and pruning ends. It’s a very important part of decision trees.

3. Selection of trees

Now, you have to choose the best tree that can work with your data smoothly.

Here are the factors that need to be considered: 

4. Entropy 

To check the homogeneity of trees, entropy needs to be inferred. If the entropy is zero, it’s homogenous; else not.

5. Knowledge gain

Once the entropy is decreased, the information is gained. This information helps to split the branches further.

• You need to calculate the entropy.
• Split the data on the basis of different criteria
• Choose the best information.

Tree depth is an important aspect. The depth informs us of the number of decisions one needs to make before we come up with a conclusion. Shallow depth trees perform better with decision tree algorithms. 

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Advantages and Disadvantages of Decision Tree

The list mentioned below highlights the major strengths and weaknesses of decision tree.

Advantages

1. Easy
2. Transparent process
3. Handle both numerical and categorical data
4. Larger the data, the better the result
5. Speed 
6. Can generate understandable rules.
7. Has the ability to perform classification without the need for much computation.
8. Gives a clear indication of the most important fields for classification or prediction.

Disadvantages

1. May overfit
2. Pruning process large
3. Optimization unguaranteed
4. Complex calculations
5. Deflection high
6. Can be less appropriate for estimation tasks, especially in cases where the ultimate aim is to determine a continuous attribute’s value. 
7. Are more prone to errors in classification problems 
8. Can be computationally expensive to train. 

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2. Random Forest

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What is Random Forest?

Random Forest is yet another very popular supervised machine learning algorithm that is used in classification and regression problems. One of the main features of this algorithm is that it can handle a dataset that contains continuous variables, in the case of regression. Simultaneously, it can also handle datasets containing categorical variables, in the case of classification. This in turn helps to deliver better results for classification problems. 

It is also used for supervised learning but is very powerful. It is very widely used. The basic difference being it does not rely on a singular decision. It assembles randomized decisions based on several decisions and makes the final decision based on the majority.

It does not search for the best prediction. Instead, it makes multiple random predictions. Thus, more diversity is attached, and prediction becomes much smoother.

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You can infer Random forest to be a collection of multiple decision trees!

How does Random Forest work?

Bagging is the process of establishing random forests while decisions work parallelly.

1. Bagging

• Take some training data set
• Make a decision tree
• Repeat the process for a definite period
• Now take the major vote. The one that wins is your decision to take.

2. Bootstrapping

Bootstrapping is randomly choosing samples from training data. This is a random procedure that promotes diversity. 

STEP by STEP

• Random choose conditions
• Calculate the root node
• Split the data
• Repeat the process
• You get a forest of decision trees

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Advantages and Disadvantages of Random Forest

Advantages

1. Powerful and highly accurate
2. No need to normalize
3. Can handle several features at once
4. Run trees in parallel ways
5. Can perform both regression and classification tasks.
6. Produces good predictions that are  easily understandable.

Disadvantages

1. They are biased to certain features sometimes
2. Slow- One of the major disadvantages of random forest is that due to the presence of a large number of trees, the algorithm can become quite slow and ineffective for real-time predictions. 
3. Can not be used for linear methods
4. Worse for high dimensional data
5. Since the random forest is a predictive modeling tool and not a descriptive one, it would be better to opt for other methods, especially if you are trying to find out the description of the relationships in your data. 

Difference between random forest and decision tree:

What are some of the important features of Random Forest?

Now that you have a basic understanding of the difference between random forest decision tree, let’s take a look at some of the important features of random forest that sets it apart. The following random forest decision tree list will also highlight some of the advantages of random forest over decision tree. 

• Diversity-  Each tree is different, and does not consider all the features. This means that not all features and attributes are considered while making an individual tree. 
• Parallelization – You get to make full use of the CPU to build random forests. The reason behind this being each tree is created out of different data and attributes, independently. 
• Stability- Random forest ensures full stability since the result is based on majority voting or averaging. 
• Train-test Split- Last but not least, yet another important feature of random forest is that you don’t have to separate the data for train and test since 30% of the data unseen by the decision tree is always available. 

When exploring random forest vs decision tree python implementations, decision trees offer simplicity and quick setup, while random forests enhance accuracy and robustness by averaging multiple trees.

For a clear random forest vs decision tree example, consider a classification task: a decision tree might quickly classify data but risks overfitting, while a random forest combines multiple trees to improve accuracy and reduce overfitting.

If you are interested in machine learning and AI applications, you might also want to make a chatbot using Python, which leverages similar concepts of classification and decision-making models in AI.

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Conclusion

Decision trees are very easy as compared to the random forest. A decision tree combines some decisions, whereas a random forest combines several decision trees. Thus, it is a long process, yet slow.

Whereas, a decision tree is fast and operates easily on large data sets, especially the linear one. The random forest model needs rigorous training. When you are trying to put up a project, you might need more than one model. Thus, a large number of random forests, more the time. 

It depends on your requirements. If you have less time to work on a model, you are bound to choose a decision tree. However, stability and reliable predictions are in the basket of random forests. 

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