I'm working with some data which includes an extensive list of dates. Some dates will appear multiple times, with each individual entry representing the date on which an event occurred. I would like to create a Time Series and Date List Plot, plotting the number of events against the date.

Eg. The data is as follows:

{"03/12/2022", "03/12/2022", "03/12/2022", "03/03/2022", "03/12/2022", "03/12/2022", "03/03/2022", "03/12/2022", "03/12/2022"}

As you can see, "03/12/2022" appears 7 times, so I'd like the value to be 7 on this date in the Time Series, and so on.

How can this be best achieved?

  • 1
    $\begingroup$ try DateHistogram[ DateString[{#, {"Month", "/", "Day", "/", "Year"}}] & /@ yourlist, "Day"]? $\endgroup$
    – kglr
    Commented Mar 25, 2023 at 17:10
  • $\begingroup$ Are your date strings normal or USA format? $\endgroup$
    – Edmund
    Commented Mar 25, 2023 at 17:53

1 Answer 1


Assuming the data are similar to the list presented in the question, it could be as simple as

process = Tally/*Transpose/*Reverse/*Apply[TemporalData[#1,{#2}]&]

Assuming events is a symbol that stores a list of event dates, similar to the one presented in the question, then

events // process

would evaluate to a TemporalData object.

Alternatively, it is possible to substitute EventSeries for TemporalData if the underlying data represent discrete events.

For more information check the official documentation for TemporalData.

  • $\begingroup$ Thanks Yosimitsu, this seems to work perfectly. It was specifically TimeSeries I was looking to use, so I substituted this for TemporalData in your suggested process. It ran very quickly for a large dataset; far faster than I anticipated. Thanks again. $\endgroup$
    – sro
    Commented Mar 26, 2023 at 10:29
  • $\begingroup$ @sro it's nice to know it worked for you; just for completeness sake, allow me to point out that a TimeSeries is special case of a TemporalData object; try using FullForm on two instances of them and notice the result; having said that, the code can easily be adapted to suit your needs, as you've already noted; take care! $\endgroup$ Commented Mar 26, 2023 at 18:07

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