To import data into ThingSpeak from a csv file, the format is very specific. Here is a doc page that describes the process. There is also a template available if you click the data improt / exprot tab on your channel view.
The documentation page Write data shows all the ways to write data. You can even use thingSpeakRead to write data in a table or timetable directly to ThingSpeak from MATLAB.
Once you have the data in ThingSpeak, there are automatic field plots and you can also write MATLAB analysis and Visualizations app instances to automate analysis or create custom plots.
