# Troubleshooting

A common issue that comes up when running `spiec.easi` is coming up with an empty network after running StARS.

For example:

    library(SpiecEasi)
    data(amgut1.filt)

    pargs <- list(seed=10010)
    se3 <- spiec.easi(amgut1.filt, method='mb', lambda.min.ratio=5e-1, nlambda=10, pulsar.params=pargs)

    getOptInd(se3)
    # [1] 1
    sum(getRefit(se3))/2
    # [1] 139

As the warning indicates, the network stability could not be determined from the lambda path. Looking at the stability along the lambda path, `se$select$stars$summary`, we can see that the maximum value of the StARS summary statistic never crosses the default threshold (0.05).

This problem we can fix by lowering `lambda.min.ratio` to explore denser networks:

    se4 <- spiec.easi(amgut1.filt, method='mb', lambda.min.ratio=1e-1, nlambda=10, pulsar.params=pargs)

We have now fit a network, but since we have only a rough, discrete sampling of networks along the lambda path, we should check how far we are from the target stability threshold (0.05):

    getStability(se4)
    # [1] 0.0003237095
    sum(getRefit(se4))/2
    # [1] 158

To get closer to the mark, we should bump up `nlambda` to more finely sample of the lambda path, which gives a denser network:

    se5 <- spiec.easi(amgut1.filt, method='mb', lambda.min.ratio=1e-1, nlambda=100, pulsar.params=pargs)

    getStability(se5)
    # [1] 0.0003237095
    sum(getRefit(se5))/2
    # [1] 210

## Common issues and solutions

### 1. Empty networks

Problem: After running `spiec.easi`, you get an empty network (no edges).

Solutions: - Lower `lambda.min.ratio` to explore denser networks - Increase `nlambda` for finer sampling of the lambda path - Check if your data has sufficient signal-to-noise ratio - Try different methods (‘mb’ vs ‘glasso’)

### 2. Very dense networks

Problem: The inferred network has too many edges.

Solutions: - Increase `lambda.min.ratio` to explore sparser networks - Adjust the StARS threshold in `pulsar.params` - Use cross-validation instead of StARS

### 3. Computational issues

Problem: The analysis takes too long or runs out of memory.

Solutions: - Use parallel processing with `ncores` parameter (Unix-like systems only) - Use B-StARS method for large datasets - Reduce `rep.num` in pulsar.params - Use batch mode for HPC clusters

### 4. Windows parallel processing issues

Problem: Error “‘mc.cores’ > 1 is not supported on Windows”

Solutions: - Use `ncores=1` for serial processing on Windows - Use snow cluster for parallel processing on Windows:

    library(parallel)
    cl <- makeCluster(4, type = "SOCK")
    pargs.windows <- list(rep.num=50, seed=10010, cluster=cl)
    se.windows <- spiec.easi(data, method='mb', pulsar.params=pargs.windows)
    stopCluster(cl)

- Use batch mode which works on all platforms
- Consider using WSL (Windows Subsystem for Linux) for Unix-like environment

### 5. Convergence issues

Problem: The algorithm doesn’t converge or gives warnings.

Solutions: - Check data preprocessing and normalization - Ensure data doesn’t have constant columns - Try different starting values - Check for missing or infinite values

### 6. Memory issues

Problem: R runs out of memory during analysis.

Solutions: - Use sparse matrices where possible - Reduce dataset size by filtering rare taxa - Use batch processing for large datasets - Increase system memory if available

## Platform-specific considerations

### Windows users:

- Default parallel processing (`mc.cores > 1`) is not supported
- Use `ncores=1` for serial processing
- Use snow cluster for parallel processing
- Consider batch mode for large datasets

### Unix-like systems (Linux, macOS):

- Full support for parallel processing with `mc.cores`
- Can use `ncores` parameter directly
- Both multicore and snow clusters available

## Diagnostic functions

SpiecEasi provides several functions to help diagnose issues:

    # Check stability along lambda path
    getStability(se)

    # Get optimal lambda index
    getOptInd(se)

    # Get summary statistics
    se$select$stars$summary

    # Check network density
    sum(getRefit(se))/2

    # Visualize stability curve
    plot(se$select$stars$summary)

    # Check platform information
    .Platform$OS.type

## Parameter tuning guidelines

### For small datasets (< 100 samples, < 50 taxa):

- `lambda.min.ratio = 1e-2`
- `nlambda = 20-50`
- `rep.num = 20-50`

### For medium datasets (100-1000 samples, 50-200 taxa):

- `lambda.min.ratio = 1e-3`
- `nlambda = 50-100`
- `rep.num = 50-100`
- Use parallel processing (Unix-like systems only)

### For large datasets (> 1000 samples, > 200 taxa):

- `lambda.min.ratio = 1e-4`
- `nlambda = 100+`
- `rep.num = 100+`
- Use B-StARS method
- Consider batch processing

### Windows-specific recommendations:

- Use `ncores=1` for serial processing
- Use snow cluster for parallel processing
- Consider batch mode for large datasets
- Use B-StARS method to reduce computational time

Session info:

    sessionInfo()
    # R version 4.6.0 (2026-04-24)
    # Platform: x86_64-pc-linux-gnu
    # Running under: Ubuntu 24.04.4 LTS
    #
    # Matrix products: default
    # BLAS:   /usr/lib/x86_64-linux-gnu/openblas-pthread/libblas.so.3
    # LAPACK: /usr/lib/x86_64-linux-gnu/openblas-pthread/libopenblasp-r0.3.26.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: Etc/UTC
    # tzcode source: system (glibc)
    #
    # attached base packages:
    # [1] stats     graphics  grDevices utils     datasets  methods   base
    #
    # other attached packages:
    # [1] igraph_2.3.1     Matrix_1.7-5     phyloseq_1.57.0  SpiecEasi_2.1.1
    # [5] BiocStyle_2.41.0
    #
    # loaded via a namespace (and not attached):
    #  [1] gtable_0.3.6        shape_1.4.6.1       xfun_0.57
    #  [4] bslib_0.11.0        ggplot2_4.0.3       Biobase_2.73.1
    #  [7] lattice_0.22-9      vctrs_0.7.3         tools_4.6.0
    # [10] generics_0.1.4      biomformat_1.41.0   stats4_4.6.0
    # [13] parallel_4.6.0      cluster_2.1.8.2     pkgconfig_2.0.3
    # [16] huge_1.6            data.table_1.18.4   RColorBrewer_1.1-3
    # [19] S7_0.2.2            S4Vectors_0.51.2    lifecycle_1.0.5
    # [22] compiler_4.6.0      farver_2.1.2        stringr_1.6.0
    # [25] Biostrings_2.81.1   Seqinfo_1.3.0       codetools_0.2-20
    # [28] permute_0.9-10      htmltools_0.5.9     sys_3.4.3
    # [31] buildtools_1.0.0    sass_0.4.10         yaml_2.3.12
    # [34] glmnet_5.0          crayon_1.5.3        jquerylib_0.1.4
    # [37] MASS_7.3-65         cachem_1.1.0        vegan_2.7-3
    # [40] iterators_1.0.14    foreach_1.5.2       nlme_3.1-169
    # [43] digest_0.6.39       stringi_1.8.7       reshape2_1.4.5
    # [46] labeling_0.4.3      maketools_1.3.2     splines_4.6.0
    # [49] ade4_1.7-24         fastmap_1.2.0       grid_4.6.0
    # [52] cli_3.6.6           magrittr_2.0.5      survival_3.8-6
    # [55] ape_5.8-1           withr_3.0.2         scales_1.4.0
    # [58] rmarkdown_2.31      XVector_0.53.0      multtest_2.69.0
    # [61] pulsar_0.3.13       VGAM_1.1-14         evaluate_1.0.5
    # [64] knitr_1.51          IRanges_2.47.1      mgcv_1.9-4
    # [67] rlang_1.2.0         Rcpp_1.1.1-1.1      glue_1.8.1
    # [70] BiocManager_1.30.27 BiocGenerics_0.59.2 jsonlite_2.0.0
    # [73] R6_2.6.1            plyr_1.8.9