Based on my understanding, I am assuming that you have a cell array "measurements" of size 3X99 and you have 99 CSV files with of the same with the 3 data types. and would like to have 3 CSV files instead of 99 by merging all the data of the same data type into one CSV file. If you still have the "measurements" cell array with you, one way would be to use "cat" function or just the vector operations to concatenate the columns and then write it into the CSV file. You can use the for-loop for doing this and then write the concatenated data at once onto your CSV file. This would improve the performance by decreasing the overhead for multiple access time to your CSV.
There are multiple ways you can concatenate the column vectors of your cell arrays, the following links might help you get started with it:
