Append data to end of human-readable file Python
Thanks for your thoughts. These two options came to my mind too but I need the mixture of both: My specific use case requires the file to be human readable - as far as I know pickling does not provide that and saving to a dictionary destroys the order. I need the data to be dropped as they need to be manipulated in other scripts before the next data is produced. 
The not very elegant way I am doing it now: numpy.savetxt() to files labeled by the run, and bash "cat" applied in the end.
In one run my python script calculates and returns the results for the variables A, B, C. 
I would like to append the results run by run, row by row to a human-readable file. 
After the runs i, I want to read the data back as numpy.arrays of the columns.
i   | A B C 
1 | 3 4 6 
2 | 4 6 7 
And maybe even access the row where e.g. A equals 3 specifically.