B/PS bulges in DESI Legacy edge-on galaxies I: Sample building
  We present the biggest up-to-date sample of edge-on galaxies with B/PS bulges
and X-structures. The sample was prepared using images from the DESI Legacy
catalogue and contains about 2000 galaxies. To find suitable candidates in
catalogue, we made the assumption that the residues (original images minus
model) of galaxies with B/PS bulges should exhibit a characteristic X-shape.
Galaxies with such features were selected by eye and then used as input data
for a neural network training, which was applied to a bigger sample of edge-on
galaxies. Using the available data and the photometric models from the
literature, we investigated the observational and statistical properties of the
sample created. Comparing the $B/D$ ratios for galaxies with and without B/PS
bulges, we found that the $B/D$ ratio for galaxies from our sample is
statistically higher, with typical values in the range $\approx 0.2-0.5$
depending on the decomposition procedure. We studied how the opening angles
$\varphi$ of the X-structure and the length of its rays are distributed in the
formed sample and found them to be consistent with previous measurements and
predictions from $N$-body models, e.g. $\varphi \gtrsim 25~\deg$, but measured
here for a much larger number of galaxies. We found a sharp increase in the
B/PS bulge fraction for stellar masses $\log M_{\star} \gtrsim 10.4$, but for
edge-on galaxies, which complements the results of previous works. The sample
can be used in future work to test various bar models and their relationship
with B/PS bulges, as well as to study their stability and evolution.
