Scaling Y axes

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  • #978 Score: 0
    Andee Rubin
    Participant
    4 pts

    I’m curious how CODAP decides to scale the Y-axis of a scatterplot, especially when a subset of points in a dataset are being shown.  I haven’t done an exhaustive exploration, but I’m surprised that sometimes the Y-axis rescales and sometimes it doesn’t – but I can’t tell you exactly the circumstances of either.  Is there something I should know that would help me predict when a Y-axis will rescale and when it won’t?

    #979
    Bill Finzer
    Keymaster

    Hi Andee,

    Interesting question. As the programmer for graphs I should be able to lay out the heuristics that determine whether a scatterplot (or any plot with a numeric axis) rescales.

    The plot will rescale when:

    • You press the Rescale button at the top of the graph’s “inspector.”
    • An attribute is added to an axis or the legend.
    • An attribute already on an axis or legend is changed to a different attribute.
    • An attribute on an axis or legend is removed.
    • One or more cases are added that have values for the plotted attributes that lie outside the current axis bounds.
    • Points that have been hidden are shown and some of the values lie outside the current axis bounds.
    • Cases that have been set aside are restored and some of the values lie outside the current axis bounds.

    The plot will not rescale when:

    • A case value is changed even if that value lies outside the current axis bounds.
    • Cases are added but their values already lie within the current axis bounds.
    • The graph is moved or resized.
    • Points are hidden or their corresponding cases are deleted or set aside.

    These heuristics evolved during the development of Fathom. I think you may be the first person expressing a desire to know what they are. And I don’t recall anyone ever asking that we change the rules, at least since the very early days.

     

    Bill

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