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I have been given a CSV file which contains the Longitude and Latitude data points for a number of mobiles that run our own internal app. The data includes the unique "ID" for the device plus a date & time stamp for each ping received.

I have been asked if I can extract the data to show only the mobiles within a specific area. I'm new to this so based on research I think I need to create polygon covering the area we are interested in and then work out which points are within that polygon.

I have downloaded and installed some software called QGIS which seems like its capable of doing what I need. I have imported the CSV file which looks correct.

Can anyone point me in the direction of how to go about getting the info i need. Ultimately I wanted to extract the points I'm interested in and then load that into kepler.gl to have a graphical view of the movements over a period of a week so I need to retain the unique "ID" and date / time stamp but for only the points within my polygon.

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    QGIS is capable of time-visualization. Check the documentation and official training manual.
    – Erik
    Commented Sep 3, 2021 at 8:56
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    Not exactly sure what you want to do - however, try Menu Vector / Analysis Tools / Count points in polygon. Otherwise, use QGIS expressions (with field calculator or select by expression) to define a filter based on overlay_within (to get the points in the polygon), combined with the condition for the timestamp.
    – Babel
    Commented Sep 3, 2021 at 9:05
  • @Babel, thanks for the info, that sounds like what i need to do. However i'm a step behind unfortunatley. I am struggaling to work out how to create the polygon. Is this something i do within QGIS or do i create it elsewhere and import it? Thanks.
    – Pigsfoot
    Commented Sep 3, 2021 at 9:30
  • Create a new lyer (I recommend: Geopackage) of polygon type, then draw the polygons. See: docs.qgis.org/3.16/en/docs/user_manual/managing_data_source/…?
    – Babel
    Commented Sep 3, 2021 at 9:35
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    It depends on what you mean by "specific area". If it's a municipality/state/country, you should be able to download boundaries from public repositories. If it's another kind of area, like a zone around a specific point, you can create a buffer. Or, you also can draw it by hand in QGIS.
    – gvanhavre
    Commented Sep 3, 2021 at 9:36

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Not exactly sure what you want to do - however, try Menu Vector / Analysis Tools / Count points in polygon. Otherwise, use QGIS expressions (with field calculator or select by expression) to define a filter based on overlay_within (to get the points in the polygon), combined with the condition for the timestamp. [Babel, 2021]

In QGIS, or other GIS software,

  1. Import .csv data
  2. create a layer
  3. create the desired polygon
  4. using Clip tool or Count Points in Polygon tool, extract/count the points.

I would personally draw the polygon and use the clip tool to create a clipped dataset with the desired area of concern, and the clip tool won't drop the attribute/table data. If it needs to be exported into .csv you can do that using QGIS.

If you are new to QGIS, here are some helpful link on the subject:

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