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help for mylabels and myticks
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Axis labels or ticks on specified scales

        mylabels lbllist , myscale(transformation_syntax) local(macname) [
                 format(format) prefix(text) suffix(text) ]

        myticks ticklist , myscale(transformation_syntax) local(macname)


Description

    mylabels and myticks generate axis labels and ticks on specified scales.
    Their use is best explained by examples, as below. Note that the label
    list lbllist and tick list ticklist will be expanded if presented as
    legal numlists and left as specified otherwise.


Remarks 

    You draw a graph and one axis is on a transformed square root scale.  You
    wish the axis labels to show untransformed values. For some values this
    is easy; for example, ylabel(0 1 2 "4" 3 "9" 4 "16" 5 "25") says use "4"
    as label for 2, and so forth. For other values and/or other
    transformations the conversion may be more difficult to do in your head,
    so that a dedicated utility is helpful.

    The idea behind mylabels is that you feed it the labels (usually, but not
    necessarily, numeric labels) that you want shown and the transformation
    being used. It will then place the appropriate specification in a local
    macro which you name. You may then use that local macro as part of a
    later graph command.

    So suppose that you want labels 0 1 4 9 16 25 36 49, and your data are
    square roots of these. Your call is mylabels 0 1 4 9 16 25 36 49,
    myscale(sqrt(@)) local(labels). Or suppose you want percents shown, and
    your data are proportions 0-1. Your call is mylabels 0(25)100,
    myscale(@/100) local(labels). Think of this in the following way: my
    graph labels that I want are 0(25)100, but my data scale is that of the
    labels divided by 100.

    For a more challenging example, see the graph on Gabriel Rossman's blog
    at http://codeandculture.wordpress.com/2010/02/08/memetracker-into-stata/

    Here the x axis variable is a date-time and the x axis labels shown are
    nice numbers in terms of clock time in milliseconds but by any other
    standard are arbitrary and awkward. The dates span a period in late 2008
    and early 2009, so monthly labels would seem more natural (even though
    not regularly spaced in terms of clock time). An example is then mylabels
    "1 Aug 2008" "1 Sep 2008" "1 Oct 2008" "1 Nov 2008" "1 Dec 2008" "1 Jan
    2009" "1 Feb 2009", myscale(clock("@", "DMY")) local(labels)

    A similar idea may be used for axis ticks.


Options

    myscale() specifies the transformation used to produce the data you have.
        Stata syntax should be used with @ as placeholder for original value.
        To show proportions as percents, specify myscale(@/100). If no
        transformation is being used, specify myscale(@). This is a required
        option.

    local(macname) inserts the option specification in local macro macname
        within the calling program's space.  Hence that macro will be
        accessible after mylabels or myticks has finished. This is helpful
        for subsequent use with graph or other graphics commands. This is a
        required option.

    format() specifies a format controlling the labels. This is a rarely
        specified option. It may be necessary to enforce the presentation of
        leading zeros.

    prefix() specifies text to be prepended to all axis labels. Specify any
        blank spaces within " ".

    suffix() specifies text to be appended to all axis labels. Specify any
        blank spaces within " ".


Examples

    . mylabels 0(10)100, myscale(sqrt(@)) local(myla)
    . myticks 5(10)95, myscale(sqrt(@)) local(myti)
    . spikeplot ... , root yla(`myla', ang(h)) ymtic(`myti')

    . mylabels 0(5)20, local(labels) myscale(@/100) suffix(" %")
    . mylabels 0(5)20, local(labels) myscale(@) prefix($)

    . su mpg
    . mylabels -1/3, myscale(`r(mean)' + (@) * `r(sd)') local(labels)
    . histogram mpg, xaxis(1 2) xla(`labels', axis(2) grid) xtitle(z scale,
        axis(2)) normal


Author

    Nicholas J. Cox, Durham University
    n.j.cox@durham.ac.uk


Acknowledgments 

    The idea behind these programs may be traced to a program by Patrick
    Royston (1996). A question from Richard Campbell led to the last example
    above. A question from Clive Nicholas and a suggestion by Philippe van
    Kerm led to a correction and further comments above. A question from
    Richard Goldstein led to the prefix() and suffix() options.  An example
    on Gabriel Rossman's blog, as noted above, provided a stimulus to
    generalise the program.


References 

    Royston, P. 1996. Flexible axis scaling. Stata Technical Bulletin 34,
        9-10 (and in STB Reprints 6, 34-36). Freely accessible at
        http://www.stata.com/products/stb/journals/stb34.pdf


Also see

    Online:  help for axis_label_options