This  code will do the simulation of circular plots, Transformation to relative distances and edge correction and GC estimation in each circular simulation plot as shown in the Figure.  For more details, please read Section 2 of Adnan, S., Maltamo, M., Coomes, D.A. and Valbuena, R., 2017. Effects of plot size, stand density, and scan density on the relationship between airborne laser scanning metrics and the Gini coefficient of tree size inequality. Canadian Journal of Forest Research, 47(12), pp.1590-1602. 

This code will calculated the stem density proportion, their corresponding basal area proportion and confidence intervals for both as shown in the Figure. For more details, See Figure 2 in Adnan, S., Maltamo, M., Coomes, D.A., García-Abril, A., Malhi, Y., Manzanera, J.A., Butt, N., Morecroft, M. and Valbuena, R., 2019. A simple approach to forest structure classification using airborne laser scanning that can be adopted across bioregions. Forest Ecology and Management, 433, pp.111-121 OR Figure 1 in Adnan, S., Valbuena, R., Kauranne, T., Gopalakrishnan, R., Maltamo, M. 2022. Optimizing the airborne laser scanning estimation of basal area larger than mean (BALM): an indicator of cohort balance in forests. Ecological Indicators , 142 (2022):109162.