1. For this 2nd week's #MakeoverMonday, I am using CAGR to analyze the iPhone sales data.

    CAGR (Compound Annual Growth Rate) is a way to calculate average annual growth rate. Here I use CAGR from last N years as a measure for the analysis:

    ([Volume 2016]/[Volume N Year Ago])^(1/N) - 1

    Here is the result.
    Click the image to go to the interactive version.
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  2. A MakeoverMonday viz is excellent as follows. The 2nd week's data set of year 2017 is on the iPhone unit sales trends. The author Haiping is from our MakeoverMonday Data Camp.
    The only pet peeve I have is about the vertical year order. My thought is that we care more about the latest change in sales. That is the focus of the analysis. We need to arrange the chart so that the latest year is at focus. So I suggested the author to make the latest year on top. 

    The author Haiping gracefully made the change. Here is the result.
    Click the picture to see the interactive version.

    It seems ordering is one of my great pet peeves. I wrote the following:

    Changing the sort order is easy. It does make a difference in highlighting the focus.
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  3. Our data is dynamic and the axis by default in Tableau will change accordingly. For example, in this Fibonacci Spiral chart, the chart and the grid are changing from iteration to iteration. This creates some visual uneasiness and can even make viewers dizzy.
    The goal here is dual: 
    - keep the origin at the center of the grid 
    - make both axis the same scale
    Both should be done dynamically

    The options in the axis editor won't help.

    So, here I would describe a technique to keep the origin fixed. I learned this when tweaking the Fibonacci viz by Zen Master Noah Salvaterra who used this technique. All credits go to Noah.

    1.Make the X axis symmetric vs 0
    - Control-drag the [x spiral axis] to the Details shelf. Right click the pill and select Edit in Shelf to add a negative sign -[x spiral axis]. This way we keep the table calculations settings the same.
    - On X axis, add a reference line based on the Minimum of -[x spiral axis]. Make the reference line invisible by hiding Label and Line in the editor.
    - Add another reference line based on the Maximum of -[x spiral axis]. 
    2.Make the Y axis symmetric vs 0
    - Do the same as above on Y axis. Use -[y spiral axis] instead.

    After the above 2 steps, the origin will be in the center. But the scales of the two axis are different. Thus a circle may look like an ellipse. To have a Cartesian grid, we need to make both axis the same scale.
    The key is to have X axis range be governed by the range of [y spiral axis]. Vice versa for Y axis. All these must be done dynamically according to the data value range. So here is the 3rd step.

    3.Make both axis the same scale
    - Control-drag both [x spiral axis] and [y spiral axis] to the Details shelf
    - On X axis, add 4 more reference lines based on Min, Max of [y spiral axis] and Min, Max of -[y spiral axis]
    - Same for Y axis using [x spiral axis] and -[x spiral axis]
    Voila, the Fibonacci Spiral will spin around a fixed origin from iteration to iteration, while both axis will scale accordingly in sync.
    Click the image to view the interactive version.
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  4. Here is the first #MakeoverMonday submission of the year 2017.


    Click image for the interactive version.

    MakeoverMonday: http://www.makeovermonday.co.uk/
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  5. In my last post, I created a continuous Fibonacci Spiral, based on Zen Master Noah Salvaterra's Fibonacci viz. He actually created the similar Golden Spiral in continuous form (to which the Fibonacci Spiral is an approximation). But it doesn't fit into the Fibonacci Rectangle.

    Then the math professor left me a piece of homework: Fit the Fibonacci Spiral into the Rectangle.

    So I spent the last few days, tweaking the viz. Finally, I got them together.
    Click the above image to view the interactive version.

    The above viz is created based on Noah's prior work which laid the foundation of math calculations. I am indebted to Noah for the inspiration.
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  6. Given a workbook URL either on Server or Tableau Public, we should be able to open it from its URL. This will make our life much easier. It should come with proper authentication of course.

    Currently, most of time we have to download a workbook first. Then open it from a file folder. If it's a recent file, we are able to open it from the server though.

    1.Add an menu item in Tableau Desktop or Tableau Public.
    2.Follow by proper authentication if necessary.
    Username: Alex
    Password: xxxxxxxx

    If you like the idea, please vote it up:
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  7. Happy New Year 2017!

    Recently I have been interested in charting mathematical functions, such as Sigmoid and Trochoids. Sigmoid has found applications in Bump and Sankey charts. For other math functions, it is just a great exercise to visualize them and to learn creating beautiful curves using Tableau.

    So, I found this Fibonacci chart below by Zen Master Noah Salvaterra who was a math professor. He has done some dazzling work in visualizing 3D objects and some pretty sophisticated math functions.

    Note that Fibonacci Spiral is only an approximation to the Golden Spiral.

    In this Fibonacci spiral chart, he drew it using straight lines between spiral points.
    So I tweaked over the holidays to draw it more like a real spiral. Certainly I used data densification to create interpolations between the spiral points. Click the image to go to the interactive version.
    First we have to create an index for the interpolating points between the spiral points. [Point_Base] is used to create bins and index with data densification.
    The key calculations of the coordinates of the interpolation are as follows:
    With the above x_spiral_axis and y_spiral_axis, I am able to draw the spiral as above.

    Voila, have a great 2017!
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