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Little Python tools, mainly useful for tasks related to machine learning, etc.
n_* - number of *
*L - list
*D - dictionary
*_ix - index (int)
*_id - ID (int or str)
*_dir *_DIR - directory, folder, relative or absolute
*_fn *_FN - file name (without directory)
*_fp *_FP - full path (directory + file name), relative or absolute