In this short vignette, we fit a sparse linear regression model with up to L > 0 non-zero effects. Generally, there is no harm in over-stating L (that is, the method is pretty robust to overfitting), except that computation will grow as L grows.
Here is a minimal example:
library(susieR)
set.seed(1)
n <- 1000
p <- 1000
beta <- rep(0,p)
beta[c(1,2,300,400)] <- 1
X <- matrix(rnorm(n*p),nrow=n,ncol=p)
y <- X %*% beta + rnorm(n)
res <- susie(X,y,L=10)
plot(coef(res)[-1],pch = 20)

Plot the ground-truth outcomes vs. the predicted outcomes:

Session information
Here are some details about the computing environment, including the versions of R, and the R packages, used to generate these results.
sessionInfo()
# R version 4.4.3 (2025-02-28)
# Platform: x86_64-conda-linux-gnu
# Running under: Linux Mint 22
#
# Matrix products: default
# BLAS/LAPACK: /home/gw/.pixi/envs/r-base/lib/libopenblasp-r0.3.30.so; LAPACK version 3.12.0
#
# locale:
# [1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C
# [3] LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8
# [5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8
# [7] LC_PAPER=en_US.UTF-8 LC_NAME=C
# [9] LC_ADDRESS=C LC_TELEPHONE=C
# [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
#
# time zone: America/New_York
# tzcode source: system (glibc)
#
# attached base packages:
# [1] stats graphics grDevices utils datasets methods base
#
# other attached packages:
# [1] susieR_0.14.21
#
# loaded via a namespace (and not attached):
# [1] Matrix_1.7-4 gtable_0.3.6 jsonlite_2.0.0 dplyr_1.1.4
# [5] compiler_4.4.3 crayon_1.5.3 Rcpp_1.1.0 tidyselect_1.2.1
# [9] parallel_4.4.3 jquerylib_0.1.4 systemfonts_1.2.3 scales_1.4.0
# [13] textshaping_1.0.3 yaml_2.3.10 fastmap_1.2.0 lattice_0.22-7
# [17] plyr_1.8.9 ggplot2_4.0.0 R6_2.6.1 generics_0.1.4
# [21] mixsqp_0.3-54 knitr_1.50 htmlwidgets_1.6.4 tibble_3.3.0
# [25] desc_1.4.3 RcppZiggurat_0.1.8 bslib_0.9.0 pillar_1.11.1
# [29] RColorBrewer_1.1-3 rlang_1.1.6 reshape_0.8.10 cachem_1.1.0
# [33] xfun_0.53 fs_1.6.6 sass_0.4.10 S7_0.2.0
# [37] RcppParallel_5.1.9 cli_3.6.5 pkgdown_2.1.3 magrittr_2.0.4
# [41] digest_0.6.37 grid_4.4.3 irlba_2.3.5.1 lifecycle_1.0.4
# [45] vctrs_0.6.5 Rfast_2.1.0 evaluate_1.0.5 glue_1.8.0
# [49] farver_2.1.2 ragg_1.5.0 rmarkdown_2.29 matrixStats_1.5.0
# [53] tools_4.4.3 pkgconfig_2.0.3 htmltools_0.5.8.1