Does the np.nan in numpy array occupy memory?

Question

I have a huge file of csv which can not be loaded into memory. Transforming it to libsvm format may save some memory. There are many nan in csv file. If I read lines and store them as np.array, with np.nan as NULL, will the array still occupy too much memory ? Does the np.nan in array also occupy memory ?

Answer 1

When working with floating point representations of numbers, non-numeric values (NaN and inf) are also represented by a specific binary pattern occupying the same number of bits as any numeric floating point value. Therefore, NaNs occupy the same amount of memory as any other number in the array.