What do 99%* of the dynamic charts ever created have in common? They are used for sets of data that stretch with time as more rows are added. In the examples cited above, there are other categories of dynamic charts, but those are much less common.

* Don’t tell anyone, but this is one of the 96% of statistics that are made up on the spot.

In the classes I teach I always start with an easier way to make dynamic charts for expanding or shrinking data sets. To answer a question the other day, I looked up the link to my blog post on this topic, and I couldn’t find it. So I had to write something, and here it is.

If you are using Excel 2003 or later, it is remarkably easy to create a chart that depends on a data set with a varying number of rows. The technique makes use of a feature introduced in Excel 2003 called the List, which was enhanced and embellished in Excel 2007, and renamed the Table. When Excel 2003 came out, the new List was the awesome killer feature that made me immediately upgrade to 2003. Unfortunately, neither Excel 2007 nor 2010 has such a feature, for me anyway.

A List or Table is a designated range that has a row of column headers and rows of data beneath this. The List or Table has the functionality of an Autofilter built in, without the Autofilter’s limitation of allowing only one per worksheet. As data is typed in the row below or in the column beside the List or Table, the List or Table expands to include this newly added data. As rows or columns are inserted or deleted, the List or Table accommodates the changes.

The most important feature of a List or Table is that any formula that references a full column of data in the List or Table updates its cell addresses when the List or Table changes its number of rows. In addition, a pivot table that uses all rows of a List or Table updates its source data range to the resized List or Table.

The chart SERIES formula updates as the List/Table changes size, making Lists/Tables ideal for many dynamic charting purposes, and here I’ll show you how that works.

The Data

Let’s start out with this typical made-up data set. It has columns of data, X and Y values in this case, and a row of headers.

Creating a List or Table

To create a list in Excel 2003, press Ctrl+L (L for List). Excel guesses what range you want to use and whether that range includes headers. The guess is almost always what you expect.

To create a list in Excel 2007, press Ctrl+L. They didn’t mess up any Excel 2003 users by changing the shortcut. The dialog is the same, except it now calls the List a Table.

Here’s what the newly created List looks like in Excel 2003. When the active cell is not within the List, there is a thin blue border highlighting the List.

If your range did not include headers, Excel inserts a row and uses dummy headers as shown below. If one of your columns did not have a header, Excel inserts a dummy header. If you want a header to appear blank, you need to type a space character in the cell.

When the active cell is within the List, the thin blue border becomes a thick blue border, Autofilter dropdown arrows appear in the header row, and the list expands by one row, giving you a data entry row denoted with a blue star in the leftmost cell. Any formatting and formulas are filled down as you enter data into this row. When you enter data in this row, the next row becomes the new record row. As you add rows to the List, any data below the List that would be overwritten is itself shifted down by one row.

The bottom right corner of the List has a small gray backwards “L” shape, which you can drag the change the dimensions of the List. You can click and drag on the thick border to move the List around the worksheet.

Here is the same data, converted into a new Table in Excel 2007. There is no border highlighting the Table, but the Table takes on the default Table formatting. A bit much, but that’s what Excel 2007 is all about. The bottom right corner of the Table is indicated with a small blue backwards “L” shape, which you can drag to change the dimensions of the Table. You can click and drag on the (unseen) border of the Table to move it around the worksheet.

When the active cell is within the Table, it does not change its appearance. The Autofilter dropdown arrows are always visible. Also, the empty row below the Table does not explicitly become a data entry row, as indicated by the unformatted row below the Table shown here. If you type data in the unformatted row below the Table, Excel assumes you want it added to the Table, and the Table and all of its formatting is filled down to include the new data.

Charting a List or Table

Here is an Excel 2003 XY chart that uses the data in our Excel 2003 List. It is created like any Excel 2003 chart: select the data and run the Chart Wizard.

Here is an Excel 2007 XY chart that uses data from our Excel 2007 Table. It is created by selecting the data and choosing the chart type from the Insert tab.

When the Excel 2003 chart is selected, you can see the chart source data highlighted in the List. Green (top row) denotes series names, purple (left column) X values, and blue (the bulk of the List) Y values.

When the Excel 2007 chart is selected, the Table is highlighted the same way, but the highlighting is a bit difficult to make out with all that shading in the default Table style.

No problem, I created my own lightly formatted Table style, and applied it to my Table. Now the highlighting shows up clearly.

The Magical Dynamic Formulas

To illustrate this wonderful behavior of Lists and Tables, I placed formulas in a row above the Excel 2003 List that calculate the sum each column of Y values in the List. This works identically in Excel 2007. The formula includes all data rows in the List, from 5 to 11.

I expanded the list by entering a new row of data. Without any further effort on my part, the formula updates to extend to row 12, the new bottom of the list.

The Magical Dynamic Charts

Here is my Excel 2003 chart from above, after the List was expanded. Each series extends one point further, plotting the data in the new row.

Here is the corresponding Excel 2007 chart, which now includes data from the new row in the Table.

The data labels in these charts are attached the the previous last point in the series, so the new point and line segment partially obscure the labels. No problem, simply rerun my Label Last Point routine to move the labels. Here’s the fixed up Excel 2003 chart.

And here’s the fixed up Excel 2007 chart.

We also note that the highlighted chart source data expands to include the entire List in 2003…

… and the entire Table in 2007.

Here is the Excel 2003 chart of the original List, with Series 1 Y selected to show the chat SERIES formula. Note the X and Y values include rows 5 through 11.

Here’s the same chart and the same chart SERIES formula after the List is expanded. The X and Y values now include rows 5 through 12. The Excel 2007 behavior is identical.

No discussion of dynamic charts in Excel is complete without a description of charts that use Lists or Tables as their source data.  It is so much easier to use Lists or Tables than dynamic names to make charts respond dynamically to the number of rows in your data.

First Post of 2011

I certainly claimed that I would post more, but there have been some circumstances beyond my control. I had to struggle to get even this one post completed this month.

Here is a plot of January’s actual high and low temperatures (dark gray bars) compared to their typical values. To all you Celsius people, water freezes at the top of the light gray bars.

Guess which morning we awoke to a malfunctioning furnace. I’ll give you a hint: see that blue diamond on January 24th, at -9°F? It got down to 47°F in the kitchen before the faulty intake compressor was replaced. Fortunately the upstairs furnace was fine.

Here’s a plot of January’s snowfall, daily totals as blue bars, and cumulative total as a dark blue line. I didn’t provide a plot of wind, but we get a lot, which means 6 inches on this chart represents 6 inches that fell on the driveway plus 6 inches that blew onto the driveway from the lawn. Each bar represents one to three hours of shoveling and snowblowing, hours I could have been blogging. The exception to shoveling hours is the total of 21.1 inches on January 12th, which was four hours plus spent clearing the driveway by my wife and two daughters. The night before and the day of this storm I drove the 12 hour round trip to Rochester to deliver my other daughter back to school, because her flight the day before had been canceled. That’s two days I couldn’t spend blogging.

Note: these charts were generated using the above technique, from an Excel 2003 List of data scraped from the accuweather.com web site.

Peltier Technical Services, Inc., Copyright © 2011.
 
Licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.
 

I was asked to expand on one of my examples, specifically to show a dynamic chart with multiple dynamic series.

I made up the following data set:

I created the following chart, and when the first series was selected, the SERIES formula showed the cell addresses of the ranges defining its data.

I defined the following dynamic names:

The OFFSET formula defining XLabels basically says, starting with cell A1, move down one cell and right zero cells, and give us the range which is as tall as the number of labels, given by the COUNTA function, and as wide as 1 cell. The other OFFSET formulas merely say, give us the range 1, 2, 3, or 4 columns to the right of XLabels. This is a shortcut that assures all dynamic ranges are the same size.

To link the series to the dynamic ranges, all that is required is to replace the static cell references in the SERIES formulas with the names defined above. Here is the first SERIES formula when the cell addresses have been replaced by the names, before pressing Enter.

Since the names were defined with the workbook as their scope, pressing Enter converted the references to workbook references, that is, referenced to MultipleDynamicChart.xls instead of Sheet1.

When data is added to the range…

… the SERIES formula is not changed, but the ranges defined by the dynamic names does change, so the chart updates.

The workbook with this example can be downloaded as a zip file, MultipleDynamicChart.zip.

Here is a partial list of my articles on dynamic charts.

• On the PTS Blog
  • Dynamic Charts
  • Dynamic Chart using Pivot Table and Range Names
  • Dynamic Chart using Pivot Table and VBA
  • Dynamic Ranges to Find and Plot Desired Columns
  • Split Data Range into Multiple Chart Series without VBA
  • VBA to Split Data Range into Multiple Chart Series
  • Dynamic Chart Source Data (VBA)
  • Display One Chart Dynamically and Interactively
• On the Peltier Tech web site
  • Dynamic and Interactive Charts (an overview)
  • Dynamic Chart
  • Another Dynamic Chart
  • Chart the Last 12 Months
  • Charting Dynamic Normalized Ranges
• Published in TechTrax ezine
  • Dynamic Charting By Dates

Peltier Technical Services, Inc., Copyright © 2011.
 
Licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.
 

Debra has provided her usual comprehensive step-by-step instructions and an example workbook you can download. Her example was done in Excel 2007, but it works as well in previous versions.

Debra contributed the first Dynamic Chart example on my fledgling web site, back when it was still just a hobby on GeoCities.

Here are more dynamic chart tutorials I’ve written:

• On the Peltier Tech Blog
  • Dynamic Charts
  • Dynamic Chart using Pivot Table and Range Names
  • Dynamic Chart using Pivot Table and VBA
  • Dynamic Ranges to Find and Plot Desired Columns
  • Split Data Range into Multiple Chart Series without VBA
  • VBA to Split Data Range into Multiple Chart Series
  • Dynamic Chart Source Data (VBA)
  • Dynamic Chart with Multiple Series
• On the Peltier Tech web site
  • Dynamic and Interactive Charts (an overview)
  • Another Dynamic Chart
  • Chart the Last 12 Months
  • Charting Dynamic Normalized Ranges
• Published in TechTrax ezine
  • Dynamic Charting By Dates

Peltier Technical Services, Inc., Copyright © 2011.
 
Licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.
 

There are a couple of ways to achieve this interactive control. There is an easy method that relies on worksheet formulas to alter the contents of the source data range of each series, and there is a more involved technique that uses VBA to programmatically adjust the chart’s source data. This post will describe the approach that uses worksheet formulas.

Checkboxes and Worksheet Formulas

Start with a column chart that includes all of the series you will allow the user to select from (A, B, and C in this example). Add a checkbox from the Forms toolbar for each series.

This works as well for a line chart, though the formulas have to be different for line and column charts.

The data range is shown below. The original source data is in J3:M8, and the three checkboxes link to the three cells in K1:M1.

There are two calculated ranges below the original data range. The category labels have simply been copied from the original range, but the other data is linked using worksheet formulas.

For the first calculated range, select K10:M15 so K10 is the active cell, enter

=IF(K$1,K3,"")
 

then hold CTRL while pressing ENTER to fill the formula into the entire selected range.

For the second calculated range, select K17:M17 so K17 is the active cell, enter

=IF(K$1,K3,"")
 

then hold CTRL while pressing ENTER to fill the formula into the entire selected range. Then select K18:M22 so K18 is the active cell, enter

=IF(K$1,K4,NA())
 

and again hold CTRL while pressing ENTER to fill the formula into the entire selected range.

If the Series B checkbox is unchecked, L1 is FALSE, so L10:L15 appear blank, L17 also appears blank, and L18:L22 contain #N/A.

The source data range for the column chart has been changed from J3:M8 to J10:M15. The data for Series B appears blank due to the “” in the formulas, which Excel treats as zero. The bars for Series B have a height of zero, so they don’t appear, and the legend entry for Series B is “”, so it doesn’t appear.

There is still a gap between the bars for Series A and Series C where Series B fits. There also is still a legend key for Series B, which is the unlabeled orange square between the green and blue squares. The legend can be hidden, but then another means is needed to identify the series in the chart.

We don’e want to use “blanks” in the source data for the line chart. Since the “” are interpreted as zero values, the line and markers for Series B lies along the horizontal axis, where Y=0. The legend entry for Series B displays no label, but the legend key still appears (the red bos and line).

For a line chart, use the range J17:J22 as the source data range. This uses #N/A instead of “” to indicate undisplayed values, so the line and markers for Series B don’t even appear in the chart. We still have that pesky unlabeled legend key, though.

It would be nice to use the same data range for both line and column charts, but the #N/A error does not preclude plotting a point in a column chart. The value is zero as in a line chart, but if you put value labels on the points, the result is a label that says “#N/A”. There is no fancy trick using number formats to hide the error.

Using the range with apparent blanks results in labels of “0″ at points corresponding to apparent blanks.

Using a custom number format of “0;;;”, we can suppress the display of any label except positive numbers (and errors).

What happens if the user gets excited and unchecks all of the boxes? The data ranges respond as expected:

And the column chart and line chart both show no data, with unlabeled legends.

CheckboxAndFormula.zip is a zipped workbook which you can download to illustrate this technique.

Checkboxes and VBA

In the next article, I will show how to use VBA in conjunction with the checkboxes to control a column or line chart with a single worksheet range and no formulas, while avoiding gaps for missing columns in the column chart and also avoiding  unlabeled legend entries.

Peltier Technical Services, Inc., Copyright © 2011.
 
Licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.
 

Jorge used a data set Nathan provided for his Poverty in the US visualization project. The chart Jorge dislikes looks like this:

It’s not really terrible, though I won’t deny it’s dull and maybe a bit cluttered. It’s more informative if less glossy than the infographic that was favored in Nathan’s challenge. But Jorge thinks that showing all of the state names was too much.

In some cases, an effective display might be to show two charts, the top five and the bottom five, and ignore the data in between.

But Jorge also wanted something interactive. So I put together a little dynamic chart that had all fifty bars but highlights the five closest to the current mouse location. As you move the mouse up and down along the chart, the highlighted region moves with the mouse.

Pretty cool, and the actual chart (see below for a download) is cooler than the static image above.

Well, Jorge is a pretty tough customer. He doesn’t just want to highlight the bars under the mouse. He wants to expand them, and shrink the unhighlighted bars. The effect is rather like an accordion. It was all I could do to keep up with Jorge’s requirements, but I cobbled together an example that I think he’ll be happy with.

Not only are a handful of bars under the mouse highlighed, but the highlighted bars are big and fat, while the unhighlighted bars are small and unobtrusive. And it’s completely interactive.

Again, the dynamic chart in the sample download is way cooler than this screen shot. An advantage of the accordion chart is that the unhighlighted bars can be compressed, shrinking the chart without shrinking the highlighted region. This ability to fit the same dynamic information into a smaller space would make this a good candidate approach for an interactive dashboard.

You can download Accordion.zip, which contains two Excel 2003 worbooks. NoAccordion1.xls is the plain version, with highlighting but no accordion-like expansion and contraction. Accordion1.xls is the deluxe version, where the highlighted region expands to grab your attention, while the unhighlighted bars shrink into the background. Open each workbook with macros enabled, then click on the chart to activate the animation.

The data is on the second worksheet of each workbook, along with a set of helper columns with the calculations that make the charts work. The code is unlocked, and you’ll be surprised how simple it is. Hardly a dozen lines in each workbook.

Update – 12 February 2009

Colin has noted that the accordion chart above would be better if all bars were labeled. I’ve adjusted the Accordion chart so the unhighlighted bars have lighter labels.

I’ve added labels for unhighlighted bars in the NoAccordion chart. In response to Colin’s other suggestions, I’ve also changed the mouse actions so that mousing past the bars doesn’t move the highlighted region, but instead clicking on a bar or label toggles that bar between highlighted and unhighlighted status. In this chart I’ve highlighted the New England states.

These workbooks are Accordion2.xls and NoAccordion2.xls, found in Accordion2.zip.

Update 2 – 12 February 2009

Dick Kusleika has made an adaptation to this chart that always displays the user’s home state. As he so astutely points out, “Does anyone really look at the top or bottom five before he finds his own state?” Read about it in Ego Charts.

Peltier Technical Services, Inc., Copyright © 2011.
 
Licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.
 

An astute reader named Eric thought that the chart would be more effective if the moving bubble left a trail of breadcrumbs, as it were, the annual mileposts along the travels of the moving bubble. I took up the challenge, and it took less time to work up than it’s taking to write this post.

I modified the data somewhat, since it was made up anyway, so that the path traced by the moving bubble was more continuous. I also defined some names in the worksheet which contain the whole series of data from the first point up to the point where the moving bubble has reached.

Here is a summary of the names, if you’re playing along at home. The first three names were present in the first version of this chart, and were used by the VBA program in its interpolation routine. The next three names are the X and Y values and the Diameters for the bubbles. Finally, I’ve included the chart series formula for the new series.

Name          Refers To
FirstColumn    =Data!$B$12
LastColumn     =Data!$B$13
ControlColumn  =Data!$B$14
AllYearsX      =OFFSET(Data!$A$3,0,1,1,GapminderExcel.xls!ControlColumn-1)
AllYearsY      =OFFSET(AllYearsX,1,0)
AllYearsD      =OFFSET(AllYearsX,2,0)
Chart Series   =SERIES("All Years",GapminderExcel.xls!AllYearsX,
               GapminderExcel.xls!AllYearsY,1,GapminderExcel.xls!AllYearsD)
 

The workbook can be found in GapminderII.zip.

Peltier Technical Services, Inc., Copyright © 2011.
 
Licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.