Sidebar

TechTip: Bar Charts: Generate Professional-Grade Charts in Your Programs in Real Time, Part 2

General
Typography
  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times

This series started with the pie chart, a useful tool that graphically summarizes data. However, pie charts only provide a "snapshot" of a moment. This tip focuses on bar charts, which show the data's evolution.

 

In the previous TechTip, I provided an example of a pie chart similar to the one below, which shows, with a little humor, the most common uses of cell phones:

 

011312RafaelFigure1

Figure 1: This pie chart shows how most people use their cell phones!

 

However, if I wanted to show how those uses evolved through time, it would be impossible to do so with only a pie chart. That's where the Bar Chart API comes in: it provides an easy way to graphically summarize period-related sets of values, as depicted in Figure 2:

 

011312RafaelFigure2

Figure 2: The uses for cell phones have evolved! (Click image to enlarge.)

 

The method used will remain the same throughout the series (read the previous tip before continuing, because I won't explain the methodology in this tip), so let's start by analyzing the template:

 

/$Header

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

  <head>

    <meta http-equiv="content-type" content="text/html; charset=utf-8"/>

    <title>

      /%PageTitle%/

    </title>

    <script src="https://www.google.com/jsapi"></script>

    <script>

      google.load("visualization", "1", {packages:["corechart"]});

      google.setOnLoadCallback(drawChart);

      function drawChart() {

        var data = new google.visualization.DataTable();

        data.addColumn('string', 'col1');

/$Column

        data.addColumn('/%ColumnType%/', '/%ColumnTitle%/');

/$TotalRows

        data.addRows(/%TotalRows%/);

/$FirstRow

        data.setValue(/%RowNbr%/, 0, '/%RowTitle%/');

/$Row

        data.setValue(/%RowNbr%/, /%ColNbr%/, /%CellValue%/);

/$Footer

        var chart = new google.visualization.BarChart(document.getElementById('chart_div'));

        chart.draw(data, {width: /%width%/,

                          height: /%height%/,

                          title: '/%ChartTitle%/',

                          vAxis: {title: '/%VAxisTitle%/'},

                          hAxis: {title: '/%HAxisTitle%/'}

                         });

      }

    </script>

  </head>

  <body>

    <div></div>

  </body>

</html>

 

The Header and Footer sections do basically the same as in the previous tip, but there are a few additional sections. These new sections are directly linked to the way the chart works; while the pie chart needed only two columns (one for the label and the other for the value), here the number of columns must be dynamic, as it depends on the number of different values within each set (the "cell phone uses" in Figure 2). However, the first column is still fixed; it's used to store the label of each value. This is why there are new sections named Column and Total Rows. Just like before, the number of rows is dynamic, but now there are two types of rows; for each set of data (the "cell phone eras" in Figure 2), there's a label (the section FirstRow, which provides the name of the "cell phone era" in Figure 2—Brick-Sized Cell Phones, for instance) and a dynamic number of values (the Row section, which corresponds to the percentages of each cell phone use throughout the "cell phone eras").

 

In order to accommodate these structural changes, the procedure GenBarChart (see QRPGLESRC/GENCHRT in the downloadable source code) also differs a bit from the GenPieChart: there are new entry parameters for the column titles and the vertical and horizontal axis titles. All the other parameters are the same as before, but I've changed some of the names in order to provide independence from the pie chart; check out P_BarRowDS, for instance. In terms of the code itself, the most notable change is related to the rows:

 

       // FirstRow And Row Sections                                       

       For W_RowIdx = 1 to C_BarMaxRows;                                  

         If P_BarRowDS(W_RowIdx).RowTitle = *Blanks;                      

           Leave;                                                         

         EndIf;                                                           

         // Update the Row variables                                      

         updHtmlVar('RowNbr'   : %Char(W_RowIdx-1));                      

         updHtmlVar('RowTitle' : %Trim(P_BarRowDS(W_RowIdx).RowTitle));   

         // Write the FirstRow section                                     

         WrtSection('FirstRow');                                          

         For W_ColIdx = 1 to C_BarMaxColumns;                             

           If P_BarRowDS(W_RowIdx).Cell(W_ColIdx).CellValue= *Zeros;      

             Leave;                                                       

           EndIf;                                                         

           updHtmlVar('ColNbr' : %Char(W_ColIdx));                        

           updHtmlVar('CellValue' : %Char(                                

                       P_BarRowDS(W_RowIdx).Cell(W_ColIdx).CellValue));   

           // Write the Row section                                       

           WrtSection('Row');

         EndFor;                     

       EndFor;

 

Since the P_BarRowDS parameter is now two-dimensional (picture this array as a spreadsheet), I need two cycles to extract all the values from the "cells". The outer cycle checks whether there is data on the row by looking for a title. If a title is found, the section FirstRow is written and the processing continues; otherwise, it leaves the outer cycle and continues to the Footer section. But the title by itself is not enough. I need values. The inner cycle starts by checking whether the "cell" contains a value and leaves the inner cycle if it doesn't, returning control to the outer cycle. If there's a value, then a Row section is written. The rest of the code is similar to the GenPieChart's, with the addition of the Axis Titles. I chose to include these as a reminder of the customization allowed by the Google API. Be sure to read the Configuration Options for more details and customization possibilities.

 

Finally, let's briefly review the TSTGENBAR1 sample program. It generates the bar chart depicted in Figure 2 by filling the P_BarColumnDS and P_BarRowDS parameters values one by one:

 

(…)

Clear P_BarColumnDS;

P_BarColumnDS(1).ColumnType  = 'number';

P_BarColumnDS(1).ColumnTitle = 'Making calls';

(…)

Clear P_BarRowDS;                                

P_BarRowDS(1).RowTitle = 'Brick-sized Cellphones';

P_BarRowDS(1).Cell(1).CellValue = 95;

P_BarRowDS(1).Cell(2).CellValue = 5;

(…)

 

Note that both arrays are being cleared before usage. This is a good practice, because the GenBarChart procedure relies on null values (*Zeros or *Blanks) to determine if there's more data.

 

The next step is invoking the procedure:

 

If GenBarChart(P_PageTitle   : P_ChartTitle :        

               P_BarColumnDS : P_BarRowDS   :        

               P_Width       : P_Height     :        

               P_VAxisTitle  : P_HAxisTitle :         

               P_FileName    : P_ErrorDesc  ) = *Off;

 

This is performed with an IF statement in order to produce the appropriate response: either a Web page with the chart or a message to the user with the description of the error.

 

Naturally, there's plenty of room for improvement, both in the GenBarChart procedure itself and in the sample programs. If you have any doubts or suggestions, feel free to email me!

 

As usual, the complete source code is provided. You can download it here.

 

I hope you enjoyed reading this tip as much as I enjoyed writing it! The next one will cover something completely different but (I hope) equally interesting: the Geo Map API.

Rafael Victoria-Pereira

Rafael Victória-Pereira has more than 20 years of IBM i experience as a programmer, analyst, and manager. Over that period, he has been an active voice in the IBM i community, encouraging and helping programmers transition to ILE and free-format RPG. Rafael has written more than 100 technical articles about topics ranging from interfaces (the topic for his first book, Flexible Input, Dazzling Output with IBM i) to modern RPG and SQL in his popular RPG Academy and SQL 101 series on mcpressonline.com and in his books Evolve Your RPG Coding and SQL for IBM i: A Database Modernization Guide. Rafael writes in an easy-to-read, practical style that is highly popular with his audience of IBM technology professionals.

Rafael is the Deputy IT Director - Infrastructures and Services at the Luis Simões Group in Portugal. His areas of expertise include programming in the IBM i native languages (RPG, CL, and DB2 SQL) and in "modern" programming languages, such as Java, C#, and Python, as well as project management and consultancy.


MC Press books written by Rafael Victória-Pereira available now on the MC Press Bookstore.

Evolve Your RPG Coding: Move from OPM to ILE...and Beyond Evolve Your RPG Coding: Move from OPM to ILE...and Beyond
Transition to modern RPG programming with this step-by-step guide through ILE and free-format RPG, SQL, and modernization techniques.
List Price $79.95

Now On Sale

Flexible Input, Dazzling Output with IBM i Flexible Input, Dazzling Output with IBM i
Uncover easier, more flexible ways to get data into your system, plus some methods for exporting and presenting the vital business data it contains.
List Price $79.95

Now On Sale

SQL for IBM i: A Database Modernization Guide SQL for IBM i: A Database Modernization Guide
Learn how to use SQL’s capabilities to modernize and enhance your IBM i database.
List Price $79.95

Now On Sale

BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

Support MC Press Online

RESOURCE CENTER

  • WHITE PAPERS

  • WEBCAST

  • TRIAL SOFTWARE

  • White Paper: Node.js for Enterprise IBM i Modernization

    SB Profound WP 5539

    If your business is thinking about modernizing your legacy IBM i (also known as AS/400 or iSeries) applications, you will want to read this white paper first!

    Download this paper and learn how Node.js can ensure that you:
    - Modernize on-time and budget - no more lengthy, costly, disruptive app rewrites!
    - Retain your IBM i systems of record
    - Find and hire new development talent
    - Integrate new Node.js applications with your existing RPG, Java, .Net, and PHP apps
    - Extend your IBM i capabilties to include Watson API, Cloud, and Internet of Things


    Read Node.js for Enterprise IBM i Modernization Now!

     

  • Profound Logic Solution Guide

    SB Profound WP 5539More than ever, there is a demand for IT to deliver innovation.
    Your IBM i has been an essential part of your business operations for years. However, your organization may struggle to maintain the current system and implement new projects.
    The thousands of customers we've worked with and surveyed state that expectations regarding the digital footprint and vision of the companyare not aligned with the current IT environment.

    Get your copy of this important guide today!

     

  • 2022 IBM i Marketplace Survey Results

    Fortra2022 marks the eighth edition of the IBM i Marketplace Survey Results. Each year, Fortra captures data on how businesses use the IBM i platform and the IT and cybersecurity initiatives it supports.

    Over the years, this survey has become a true industry benchmark, revealing to readers the trends that are shaping and driving the market and providing insight into what the future may bring for this technology.

  • Brunswick bowls a perfect 300 with LANSA!

    FortraBrunswick is the leader in bowling products, services, and industry expertise for the development and renovation of new and existing bowling centers and mixed-use recreation facilities across the entertainment industry. However, the lifeblood of Brunswick’s capital equipment business was running on a 15-year-old software application written in Visual Basic 6 (VB6) with a SQL Server back-end. The application was at the end of its life and needed to be replaced.
    With the help of Visual LANSA, they found an easy-to-use, long-term platform that enabled their team to collaborate, innovate, and integrate with existing systems and databases within a single platform.
    Read the case study to learn how they achieved success and increased the speed of development by 30% with Visual LANSA.

     

  • Progressive Web Apps: Create a Universal Experience Across All Devices

    LANSAProgressive Web Apps allow you to reach anyone, anywhere, and on any device with a single unified codebase. This means that your applications—regardless of browser, device, or platform—instantly become more reliable and consistent. They are the present and future of application development, and more and more businesses are catching on.
    Download this whitepaper and learn:

    • How PWAs support fast application development and streamline DevOps
    • How to give your business a competitive edge using PWAs
    • What makes progressive web apps so versatile, both online and offline

     

     

  • The Power of Coding in a Low-Code Solution

    LANSAWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed.
    Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

    • Discover the benefits of Low-code's quick application creation
    • Understand the differences in model-based and language-based Low-Code platforms
    • Explore the strengths of LANSA's Low-Code Solution to Low-Code’s biggest drawbacks

     

     

  • Why Migrate When You Can Modernize?

    LANSABusiness users want new applications now. Market and regulatory pressures require faster application updates and delivery into production. Your IBM i developers may be approaching retirement, and you see no sure way to fill their positions with experienced developers. In addition, you may be caught between maintaining your existing applications and the uncertainty of moving to something new.
    In this white paper, you’ll learn how to think of these issues as opportunities rather than problems. We’ll explore motivations to migrate or modernize, their risks and considerations you should be aware of before embarking on a (migration or modernization) project.
    Lastly, we’ll discuss how modernizing IBM i applications with optimized business workflows, integration with other technologies and new mobile and web user interfaces will enable IT – and the business – to experience time-added value and much more.

     

  • UPDATED: Developer Kit: Making a Business Case for Modernization and Beyond

    Profound Logic Software, Inc.Having trouble getting management approval for modernization projects? The problem may be you're not speaking enough "business" to them.

    This Developer Kit provides you study-backed data and a ready-to-use business case template to help get your very next development project approved!

  • What to Do When Your AS/400 Talent Retires

    FortraIT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators is small.

    This guide offers strategies and software suggestions to help you plan IT staffing and resources and smooth the transition after your AS/400 talent retires. Read on to learn:

    • Why IBM i skills depletion is a top concern
    • How leading organizations are coping
    • Where automation will make the biggest impact

     

  • Node.js on IBM i Webinar Series Pt. 2: Setting Up Your Development Tools

    Profound Logic Software, Inc.Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application. In Part 2, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Attend this webinar to learn:

    • Different tools to develop Node.js applications on IBM i
    • Debugging Node.js
    • The basics of Git and tools to help those new to it
    • Using NodeRun.com as a pre-built development environment

     

     

  • Expert Tips for IBM i Security: Beyond the Basics

    SB PowerTech WC GenericIn this session, IBM i security expert Robin Tatam provides a quick recap of IBM i security basics and guides you through some advanced cybersecurity techniques that can help you take data protection to the next level. Robin will cover:

    • Reducing the risk posed by special authorities
    • Establishing object-level security
    • Overseeing user actions and data access

    Don't miss this chance to take your knowledge of IBM i security beyond the basics.

     

     

  • 5 IBM i Security Quick Wins

    SB PowerTech WC GenericIn today’s threat landscape, upper management is laser-focused on cybersecurity. You need to make progress in securing your systems—and make it fast.
    There’s no shortage of actions you could take, but what tactics will actually deliver the results you need? And how can you find a security strategy that fits your budget and time constraints?
    Join top IBM i security expert Robin Tatam as he outlines the five fastest and most impactful changes you can make to strengthen IBM i security this year.
    Your system didn’t become unsecure overnight and you won’t be able to turn it around overnight either. But quick wins are possible with IBM i security, and Robin Tatam will show you how to achieve them.

  • Security Bulletin: Malware Infection Discovered on IBM i Server!

    SB PowerTech WC GenericMalicious programs can bring entire businesses to their knees—and IBM i shops are not immune. It’s critical to grasp the true impact malware can have on IBM i and the network that connects to it. Attend this webinar to gain a thorough understanding of the relationships between:

    • Viruses, native objects, and the integrated file system (IFS)
    • Power Systems and Windows-based viruses and malware
    • PC-based anti-virus scanning versus native IBM i scanning

    There are a number of ways you can minimize your exposure to viruses. IBM i security expert Sandi Moore explains the facts, including how to ensure you're fully protected and compliant with regulations such as PCI.

     

     

  • Encryption on IBM i Simplified

    SB PowerTech WC GenericDB2 Field Procedures (FieldProcs) were introduced in IBM i 7.1 and have greatly simplified encryption, often without requiring any application changes. Now you can quickly encrypt sensitive data on the IBM i including PII, PCI, PHI data in your physical files and tables.
    Watch this webinar to learn how you can quickly implement encryption on the IBM i. During the webinar, security expert Robin Tatam will show you how to:

    • Use Field Procedures to automate encryption and decryption
    • Restrict and mask field level access by user or group
    • Meet compliance requirements with effective key management and audit trails

     

  • Lessons Learned from IBM i Cyber Attacks

    SB PowerTech WC GenericDespite the many options IBM has provided to protect your systems and data, many organizations still struggle to apply appropriate security controls.
    In this webinar, you'll get insight into how the criminals accessed these systems, the fallout from these attacks, and how the incidents could have been avoided by following security best practices.

    • Learn which security gaps cyber criminals love most
    • Find out how other IBM i organizations have fallen victim
    • Get the details on policies and processes you can implement to protect your organization, even when staff works from home

    You will learn the steps you can take to avoid the mistakes made in these examples, as well as other inadequate and misconfigured settings that put businesses at risk.

     

     

  • The Power of Coding in a Low-Code Solution

    SB PowerTech WC GenericWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed.
    Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

    • Discover the benefits of Low-code's quick application creation
    • Understand the differences in model-based and language-based Low-Code platforms
    • Explore the strengths of LANSA's Low-Code Solution to Low-Code’s biggest drawbacks

     

     

  • Node Webinar Series Pt. 1: The World of Node.js on IBM i

    SB Profound WC GenericHave you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application.
    Part 1 will teach you what Node.js is, why it's a great option for IBM i shops, and how to take advantage of the ecosystem surrounding Node.
    In addition to background information, our Director of Product Development Scott Klement will demonstrate applications that take advantage of the Node Package Manager (npm).
    Watch Now.

  • The Biggest Mistakes in IBM i Security

    SB Profound WC Generic The Biggest Mistakes in IBM i Security
    Here’s the harsh reality: cybersecurity pros have to get their jobs right every single day, while an attacker only has to succeed once to do incredible damage.
    Whether that’s thousands of exposed records, millions of dollars in fines and legal fees, or diminished share value, it’s easy to judge organizations that fall victim. IBM i enjoys an enviable reputation for security, but no system is impervious to mistakes.
    Join this webinar to learn about the biggest errors made when securing a Power Systems server.
    This knowledge is critical for ensuring integrity of your application data and preventing you from becoming the next Equifax. It’s also essential for complying with all formal regulations, including SOX, PCI, GDPR, and HIPAA
    Watch Now.

  • Comply in 5! Well, actually UNDER 5 minutes!!

    SB CYBRA PPL 5382

    TRY the one package that solves all your document design and printing challenges on all your platforms.

    Produce bar code labels, electronic forms, ad hoc reports, and RFID tags – without programming! MarkMagic is the only document design and print solution that combines report writing, WYSIWYG label and forms design, and conditional printing in one integrated product.

    Request your trial now!

  • Backup and Recovery on IBM i: Your Strategy for the Unexpected

    FortraRobot automates the routine tasks of iSeries backup and recovery, saving you time and money and making the process safer and more reliable. Automate your backups with the Robot Backup and Recovery Solution. Key features include:
    - Simplified backup procedures
    - Easy data encryption
    - Save media management
    - Guided restoration
    - Seamless product integration
    Make sure your data survives when catastrophe hits. Try the Robot Backup and Recovery Solution FREE for 30 days.

  • Manage IBM i Messages by Exception with Robot

    SB HelpSystems SC 5413Managing messages on your IBM i can be more than a full-time job if you have to do it manually. How can you be sure you won’t miss important system events?
    Automate your message center with the Robot Message Management Solution. Key features include:
    - Automated message management
    - Tailored notifications and automatic escalation
    - System-wide control of your IBM i partitions
    - Two-way system notifications from your mobile device
    - Seamless product integration
    Try the Robot Message Management Solution FREE for 30 days.

  • Easiest Way to Save Money? Stop Printing IBM i Reports

    FortraRobot automates report bursting, distribution, bundling, and archiving, and offers secure, selective online report viewing.
    Manage your reports with the Robot Report Management Solution. Key features include:

    - Automated report distribution
    - View online without delay
    - Browser interface to make notes
    - Custom retention capabilities
    - Seamless product integration
    Rerun another report? Never again. Try the Robot Report Management Solution FREE for 30 days.

  • Hassle-Free IBM i Operations around the Clock

    SB HelpSystems SC 5413For over 30 years, Robot has been a leader in systems management for IBM i.
    Manage your job schedule with the Robot Job Scheduling Solution. Key features include:
    - Automated batch, interactive, and cross-platform scheduling
    - Event-driven dependency processing
    - Centralized monitoring and reporting
    - Audit log and ready-to-use reports
    - Seamless product integration
    Scale your software, not your staff. Try the Robot Job Scheduling Solution FREE for 30 days.