The real sparsity of nature can be discussed from several other aspects.

Two hypotheses: 1, the change of element position in the data does not change the sparsity measure; 2. Sparsity is determined by the amplitude of elements.

Several conditions for measuring sparsity are:

The corresponding mathematical expression:

Analysis and summary of these properties of common functions in mathematics;

Quantify the sparsity by the length of the measured vector, and you can get:

Kolmogorov complexity and minimal description discussed this year

Length is also one of the sparse metrics.