I have a log-file which lists a time and date I logged in on one website. I want to create a BarChart which compares the amount of times I did it every day. How to I make Mathematica count the amount of times, when I logged in on a certain day?


You could use DateHistogram for this:

logs = Import["~/Downloads/dat1.csv"];
logs = Rest[logs]; (* drop the headers *)

This bit may look a bit complicated, but it's just combining the date and time strings and converting them to a DateObject, with some help about how they're formatted:

times = DateObject[{# <> " " <> #2, {"MonthShort", "DayShort", 
       "YearShort", "Hour24", "Minute"}}] & @@@ logs;

Create a histogram, with one bin for each day:

DateHistogram[times, "Day", DateTicksFormat -> {"MonthShort", "/", "Day"}]

enter image description here

summary = Length /@ SemanticImport["C:/temp/temp.csv"][GroupBy["Date"]]
BarChart[summary, ChartLabels -> Keys@Normal@summary,  ImageSize -> Large]

You can play with the labels as much as you wish. E.g.,

labels = DateString[#, {"MonthNameShort", "-", "Day"}] & /@ Keys@Normal@summary
BarChart[summary, ChartLabels -> labels]

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