Visualize a Personal Email Timeline 

Import data on the times and categories of email messages.

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X data = SemanticImport["ExampleData/dates-categories"]

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Get a list of all the message categories.

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X categories = Union[Normal[data][[All, 2]]]

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Plot the numbers of messages by category and date.

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X DateListPlot[ With[{category = #}, {#[[1]], Length[#]} & /@ GatherBy[ Normal[data[Select[#[[2]] === category &]][All, 1]], (# /@ {"Month", "Year"}) &] ] & /@ categories, PlotRange -> All, PlotLegends -> categories]

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