Import csv into labplot creates new columns, does not append new rows

I have several years of weather data that I want to display and create charts from. I had created a labplot file from the first couple of years. After trying around for a while, this worked (although probably very imperfectly, I’m a noob, and there will be another question on how to do it properly).

Anyway, I wanted to append the new data to the already existing (via “File - Import Data - From File”. But whenever I try to import it (csv or xlsx, no difference), it would append new columns, not new rows. Column headers are the same, with or without index etc.

I’m pretty sure it’s my own mistake, but I cannot find it. Any help out there?

Yes, the import mode is referring to the columns, not rows. So, if you select “Append”, it’s appending new columns in the already existing spreadsheet. Appending of rows for the same structure of columns is not possible yet in the import file dialog. Though, it’s possible to add new rows if you have a data source that is being changed all the time and you want LabPlot to update (to re-read) the imported data and the visualizations on changes in the external file. For this we have this object “Live Data Source”. But I’m not sure this is really your use-case. Maybe you can explain what you want/need to achieve.