MQL4 and MQL5 Programming Articles

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Study the MQL5 language for programming trading strategies in numerous published articles mostly written by you - the community members. The articles are grouped into categories to help you quicker find answers to any questions related to programming: Integration, Tester, Trading Strategies, etc.

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Developing a Replay System (Part 37): Paving the Path (I)

Developing a Replay System (Part 37): Paving the Path (I)

In this article, we will finally begin to do what we wanted to do much earlier. However, due to the lack of "solid ground", I did not feel confident to present this part publicly. Now I have the basis to do this. I suggest that you focus as much as possible on understanding the content of this article. I mean not simply reading it. I want to emphasize that if you do not understand this article, you can completely give up hope of understanding the content of the following ones.
Poll: Traders’ Estimate of the Mobile Terminal
Poll: Traders’ Estimate of the Mobile Terminal

Poll: Traders’ Estimate of the Mobile Terminal

Unfortunately, there are no clear projections available at this moment about the future of the mobile trading. However, there are a lot of speculations surrounding this matter. In our attempt to resolve this ambiguity we decided to conduct a survey among traders to find out their opinion about our mobile terminals. Through the efforts of this survey, we have managed to established a clear picture of what our clients currently think about the product as well as their requests and wishes in future developments of our mobile terminals.
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Developing a Replay System — Market simulation (Part 07): First improvements (II)

Developing a Replay System — Market simulation (Part 07): First improvements (II)

In the previous article, we made some fixes and added tests to our replication system to ensure the best possible stability. We also started creating and using a configuration file for this system.
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Population optimization algorithms: Changing shape, shifting probability distributions and testing on Smart Cephalopod (SC)

Population optimization algorithms: Changing shape, shifting probability distributions and testing on Smart Cephalopod (SC)

The article examines the impact of changing the shape of probability distributions on the performance of optimization algorithms. We will conduct experiments using the Smart Cephalopod (SC) test algorithm to evaluate the efficiency of various probability distributions in the context of optimization problems.
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Neural networks made easy (Part 65): Distance Weighted Supervised Learning (DWSL)

Neural networks made easy (Part 65): Distance Weighted Supervised Learning (DWSL)

In this article, we will get acquainted with an interesting algorithm that is built at the intersection of supervised and reinforcement learning methods.
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Developing a Replay System (Part 31): Expert Advisor project — C_Mouse class (V)

Developing a Replay System (Part 31): Expert Advisor project — C_Mouse class (V)

We need a timer that can show how much time is left till the end of the replay/simulation run. This may seem at first glance to be a simple and quick solution. Many simply try to adapt and use the same system that the trading server uses. But there's one thing that many people don't consider when thinking about this solution: with replay, and even m ore with simulation, the clock works differently. All this complicates the creation of such a system.
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Category Theory in MQL5 (Part 6): Monomorphic Pull-Backs and Epimorphic Push-Outs

Category Theory in MQL5 (Part 6): Monomorphic Pull-Backs and Epimorphic Push-Outs

Category Theory is a diverse and expanding branch of Mathematics which is only recently getting some coverage in the MQL5 community. These series of articles look to explore and examine some of its concepts & axioms with the overall goal of establishing an open library that provides insight while also hopefully furthering the use of this remarkable field in Traders' strategy development.
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Data Science and Machine Learning (Part 16): A Refreshing Look at Decision Trees

Data Science and Machine Learning (Part 16): A Refreshing Look at Decision Trees

Dive into the intricate world of decision trees in the latest installment of our Data Science and Machine Learning series. Tailored for traders seeking strategic insights, this article serves as a comprehensive recap, shedding light on the powerful role decision trees play in the analysis of market trends. Explore the roots and branches of these algorithmic trees, unlocking their potential to enhance your trading decisions. Join us for a refreshing perspective on decision trees and discover how they can be your allies in navigating the complexities of financial markets.
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The case for using a Composite Data Set this Q4 in weighing SPDR XLY's next performance

The case for using a Composite Data Set this Q4 in weighing SPDR XLY's next performance

We consider XLY, SPDR’s consumer discretionary spending ETF and see if with tools in MetaTrader’s IDE we can sift through an array of data sets in selecting what could work with a forecasting model with a forward outlook of not more than a year.
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Developing a quality factor for Expert Advisors

Developing a quality factor for Expert Advisors

In this article, we will see how to develop a quality score that your Expert Advisor can display in the strategy tester. We will look at two well-known calculation methods – Van Tharp and Sunny Harris.
How to Become a Participant of Automated Trading Championship 2008?
How to Become a Participant of Automated Trading Championship 2008?

How to Become a Participant of Automated Trading Championship 2008?

The main purpose of the Championship is to popularize automated trading and accumulate practical information in this field of knowledge. As the Organizer of the Championship, we are doing our best to provide a fair competition and suppress all attempts to “play booty”. It is this reasoning that sets the strict Rules of the Championship.
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DoEasy. Controls (Part 11): WinForms objects — groups, CheckedListBox WinForms object

DoEasy. Controls (Part 11): WinForms objects — groups, CheckedListBox WinForms object

The article considers grouping WinForms objects and creation of the CheckBox objects list object.
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StringFormat(). Review and ready-made examples

StringFormat(). Review and ready-made examples

The article continues the review of the PrintFormat() function. We will briefly look at formatting strings using StringFormat() and their further use in the program. We will also write templates to display symbol data in the terminal journal. The article will be useful for both beginners and experienced developers.
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Custom Indicators (Part 1): A Step-by-Step Introductory Guide to Developing Simple Custom Indicators in MQL5

Custom Indicators (Part 1): A Step-by-Step Introductory Guide to Developing Simple Custom Indicators in MQL5

Learn how to create custom indicators using MQL5. This introductory article will guide you through the fundamentals of building simple custom indicators and demonstrate a hands-on approach to coding different custom indicators for any MQL5 programmer new to this interesting topic.
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Population optimization algorithms: Simulated Annealing (SA) algorithm. Part I

Population optimization algorithms: Simulated Annealing (SA) algorithm. Part I

The Simulated Annealing algorithm is a metaheuristic inspired by the metal annealing process. In the article, we will conduct a thorough analysis of the algorithm and debunk a number of common beliefs and myths surrounding this widely known optimization method. The second part of the article will consider the custom Simulated Isotropic Annealing (SIA) algorithm.
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Developing a Replay System — Market simulation (Part 16): New class system

Developing a Replay System — Market simulation (Part 16): New class system

We need to organize our work better. The code is growing, and if this is not done now, then it will become impossible. Let's divide and conquer. MQL5 allows the use of classes which will assist in implementing this task, but for this we need to have some knowledge about classes. Probably the thing that confuses beginners the most is inheritance. In this article, we will look at how to use these mechanisms in a practical and simple way.
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Developing a Replay System — Market simulation (Part 18): Ticks and more ticks (II)

Developing a Replay System — Market simulation (Part 18): Ticks and more ticks (II)

Obviously the current metrics are very far from the ideal time for creating a 1-minute bar. That's the first thing we are going to fix. Fixing the synchronization problem is not difficult. This may seem hard, but it's actually quite simple. We did not make the required correction in the previous article since its purpose was to explain how to transfer the tick data that was used to create the 1-minute bars on the chart into the Market Watch window.
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Category Theory in MQL5 (Part 21): Natural Transformations with LDA

Category Theory in MQL5 (Part 21): Natural Transformations with LDA

This article, the 21st in our series, continues with a look at Natural Transformations and how they can be implemented using linear discriminant analysis. We present applications of this in a signal class format, like in the previous article.
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Neural networks made easy (Part 41): Hierarchical models

Neural networks made easy (Part 41): Hierarchical models

The article describes hierarchical training models that offer an effective approach to solving complex machine learning problems. Hierarchical models consist of several levels, each of which is responsible for different aspects of the task.
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Category Theory in MQL5 (Part 19): Naturality Square Induction

Category Theory in MQL5 (Part 19): Naturality Square Induction

We continue our look at natural transformations by considering naturality square induction. Slight restraints on multicurrency implementation for experts assembled with the MQL5 wizard mean we are showcasing our data classification abilities with a script. Principle applications considered are price change classification and thus its forecasting.
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Developing a Replay System (Part 36): Making Adjustments (II)

Developing a Replay System (Part 36): Making Adjustments (II)

One of the things that can make our lives as programmers difficult is assumptions. In this article, I will show you how dangerous it is to make assumptions: both in MQL5 programming, where you assume that the type will have a certain value, and in MetaTrader 5, where you assume that different servers work the same.
All about Automated Trading Championship: Interviews with the Participants'07
All about Automated Trading Championship: Interviews with the Participants'07

All about Automated Trading Championship: Interviews with the Participants'07

The published interviews of Championship 2007 bear the stamp of the results obtained during the preceding contest. The first Championship evoked a wide response on the internet and in printings. The leading developer of the MetaQuotes Software Corp. tells about changes made to the forthcoming Automated Trading Championship 2007. We put our questions to the developer of a well-known indicating complex ZUP, Eugeni Neumoin (nen) and spoke to an equity trader, Alexander Pozdnishev (AlexSilver).
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DoEasy. Controls (Part 14): New algorithm for naming graphical elements. Continuing work on the TabControl WinForms object

DoEasy. Controls (Part 14): New algorithm for naming graphical elements. Continuing work on the TabControl WinForms object

In this article, I will create a new algorithm for naming all graphical elements meant for building custom graphics, as well as continue developing the TabControl WinForms object.
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MQL5 Wizard Techniques you should know (Part 07): Dendrograms

MQL5 Wizard Techniques you should know (Part 07): Dendrograms

Data classification for purposes of analysis and forecasting is a very diverse arena within machine learning and it features a large number of approaches and methods. This piece looks at one such approach, namely Agglomerative Hierarchical Classification.
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Category Theory in MQL5 (Part 17): Functors and Monoids

Category Theory in MQL5 (Part 17): Functors and Monoids

This article, the final in our series to tackle functors as a subject, revisits monoids as a category. Monoids which we have already introduced in these series are used here to aid in position sizing, together with multi-layer perceptrons.
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Neural networks made easy (Part 61): Optimism issue in offline reinforcement learning

Neural networks made easy (Part 61): Optimism issue in offline reinforcement learning

During the offline learning, we optimize the Agent's policy based on the training sample data. The resulting strategy gives the Agent confidence in its actions. However, such optimism is not always justified and can cause increased risks during the model operation. Today we will look at one of the methods to reduce these risks.
All about Automated Trading Championship: Additional Materials of Championships 2006-2007
All about Automated Trading Championship: Additional Materials of Championships 2006-2007

All about Automated Trading Championship: Additional Materials of Championships 2006-2007

We present to you a selection of these materials that are divided into several parts. The present one contains additional materials about automated trading, Expert Advisors development, etc.
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GUI: Tips and Tricks for creating your own Graphic Library in MQL

GUI: Tips and Tricks for creating your own Graphic Library in MQL

We'll go through the basics of GUI libraries so that you can understand how they work or even start making your own.
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Cross-validation and basics of causal inference in CatBoost models, export to ONNX format

Cross-validation and basics of causal inference in CatBoost models, export to ONNX format

The article proposes the method of creating bots using machine learning.
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Developing a Replay System (Part 29): Expert Advisor project — C_Mouse class (III)

Developing a Replay System (Part 29): Expert Advisor project — C_Mouse class (III)

After improving the C_Mouse class, we can focus on creating a class designed to create a completely new framework fr our analysis. We will not use inheritance or polymorphism to create this new class. Instead, we will change, or better said, add new objects to the price line. That's what we will do in this article. In the next one, we will look at how to change the analysis. All this will be done without changing the code of the C_Mouse class. Well, actually, it would be easier to achieve this using inheritance or polymorphism. However, there are other methods to achieve the same result.
Method of Determining Errors in Code by Commenting
Method of Determining Errors in Code by Commenting

Method of Determining Errors in Code by Commenting

The article describes a method of searching the errors in the MQL4 code that is based on commenting. This method is found to be a useful one in case of problems occuring during the compilation caused by the errors in a reasonably large code.
All about Automated Trading Championship: Interviews with the Participants'06
All about Automated Trading Championship: Interviews with the Participants'06

All about Automated Trading Championship: Interviews with the Participants'06

Interviews with the Participants of Automated Trading Championship 2006 demonstrated a great variety of views of automated trading and trading as a whole. You can see yourselves which ideas turned out to work better during the Championship and which of them could not pass the critical verification through a three-month long "test-drive" on a contest account.
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Population optimization algorithms: Simulated Isotropic Annealing (SIA) algorithm. Part II

Population optimization algorithms: Simulated Isotropic Annealing (SIA) algorithm. Part II

The first part was devoted to the well-known and popular algorithm - simulated annealing. We have thoroughly considered its pros and cons. The second part of the article is devoted to the radical transformation of the algorithm, which turns it into a new optimization algorithm - Simulated Isotropic Annealing (SIA).
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Category Theory in MQL5 (Part 12): Orders

Category Theory in MQL5 (Part 12): Orders

This article which is part of a series that follows Category Theory implementation of Graphs in MQL5, delves in Orders. We examine how concepts of Order-Theory can support monoid sets in informing trade decisions by considering two major ordering types.
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Neural networks are easy (Part 59): Dichotomy of Control (DoC)

Neural networks are easy (Part 59): Dichotomy of Control (DoC)

In the previous article, we got acquainted with the Decision Transformer. But the complex stochastic environment of the foreign exchange market did not allow us to fully implement the potential of the presented method. In this article, I will introduce an algorithm that is aimed at improving the performance of algorithms in stochastic environments.
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Permuting price bars in MQL5

Permuting price bars in MQL5

In this article we present an algorithm for permuting price bars and detail how permutation tests can be used to recognize instances where strategy performance has been fabricated to deceive potential buyers of Expert Advisors.
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MQL5 Wizard Techniques you should know (Part 12): Newton Polynomial

MQL5 Wizard Techniques you should know (Part 12): Newton Polynomial

Newton’s polynomial, which creates quadratic equations from a set of a few points, is an archaic but interesting approach at looking at a time series. In this article we try to explore what aspects could be of use to traders from this approach as well as address its limitations.
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Population optimization algorithms: Intelligent Water Drops (IWD) algorithm

Population optimization algorithms: Intelligent Water Drops (IWD) algorithm

The article considers an interesting algorithm derived from inanimate nature - intelligent water drops (IWD) simulating the process of river bed formation. The ideas of this algorithm made it possible to significantly improve the previous leader of the rating - SDS. As usual, the new leader (modified SDSm) can be found in the attachment.
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Developing an MQL5 Reinforcement Learning agent with RestAPI integration (Part 1): How to use RestAPIs in MQL5

Developing an MQL5 Reinforcement Learning agent with RestAPI integration (Part 1): How to use RestAPIs in MQL5

In this article we will talk about the importance of APIs (Application Programming Interface) for interaction between different applications and software systems. We will see the role of APIs in simplifying interactions between applications, allowing them to efficiently share data and functionality.
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Developing an MQTT client for MetaTrader 5: a TDD approach — Part 2

Developing an MQTT client for MetaTrader 5: a TDD approach — Part 2

This article is part of a series describing our development steps of a native MQL5 client for the MQTT protocol. In this part we describe our code organization, the first header files and classes, and how we are writing our tests. This article also includes brief notes about the Test-Driven-Development practice and how we are applying it to this project.