# detect_all_events function: cgmguru and iglu-compatible event preprocessing

## Relationship to iglu

`cgmguru::detect_all_events()` is an independent C++/Rcpp implementation of event calculation and CGM summary output. Its preprocessing is designed to be compatible with the event grid semantics used by `iglu`: subject-specific reading intervals, a midnight-aligned full-day grid, interpolation up to `inter_gap`, removal of larger gap-masked rows, and segment-wise event classification.

When `reading_minutes` is omitted or `NULL`, cgmguru calculates it automatically per subject from the median positive timestamp spacing in the input data.

The `iglu` package is used here as a formal reference, source of public example datasets, and comparison target. cgmguru does not call `iglu` at runtime for its core algorithms.

## Datasets

We use two CGM example datasets shipped with `iglu`:

- `example_data_5_subject`: 5 subjects
- `example_data_hall`: 19 subjects

    data(example_data_5_subject, package = "iglu")
    data(example_data_hall, package = "iglu")

    # Base-R summaries (no external dependencies)
    summary_5 <- data.frame(
      rows = nrow(example_data_5_subject),
      subjects = length(unique(example_data_5_subject$id)),
      time_min = min(example_data_5_subject$time),
      time_max = max(example_data_5_subject$time),
      gl_min = min(example_data_5_subject$gl, na.rm = TRUE),
      gl_max = max(example_data_5_subject$gl, na.rm = TRUE)
    )

    summary_5
    #>    rows subjects            time_min            time_max gl_min gl_max
    #> 1 13866        5 2015-02-24 17:31:29 2015-06-19 08:59:36     50    400

    cat("Note: The 'iglu' package is not available; vignette examples are skipped.\n")

## iglu: episode_calculation

`iglu::episode_calculation()` identifies hypo/hyperglycemia episodes.

    iglu_episodes_5 <- iglu::episode_calculation(
      data = example_data_5_subject
    )
    print(iglu_episodes_5)
    #> # A tibble: 35 × 7
    #>    id        type  level avg_ep_per_day avg_ep_duration avg_ep_gl total_episodes
    #>    <fct>     <chr> <chr>          <dbl>           <dbl>     <dbl>          <dbl>
    #>  1 Subject 1 hypo  lv1           0.0899            35        68.6              1
    #>  2 Subject 1 hypo  lv2           0                  0        NA                0
    #>  3 Subject 1 hypo  exte…         0                  0        NA                0
    #>  4 Subject 1 hyper lv1           1.44              80.3     200.              16
    #>  5 Subject 1 hyper lv2           0.180             30       264.               2
    #>  6 Subject 1 hypo  lv1_…         0.0899            35        68.6              1
    #>  7 Subject 1 hyper lv1_…         1.26              79.6     195.              14
    #>  8 Subject 2 hypo  lv1           0                  0        NA                0
    #>  9 Subject 2 hypo  lv2           0                  0        NA                0
    #> 10 Subject 2 hypo  exte…         0                  0        NA                0
    #> # ℹ 25 more rows

    iglu_episodes_hall <- iglu::episode_calculation(
      data = example_data_hall
    )
    print(iglu_episodes_hall)
    #> # A tibble: 133 × 7
    #>    id        type  level avg_ep_per_day avg_ep_duration avg_ep_gl total_episodes
    #>    <chr>     <chr> <chr>          <dbl>           <dbl>     <dbl>          <dbl>
    #>  1 1636-69-… hypo  lv1            0.468            15        68.1              3
    #>  2 1636-69-… hypo  lv2            0                 0        NA                0
    #>  3 1636-69-… hypo  exte…          0                 0        NA                0
    #>  4 1636-69-… hyper lv1            0.623            57.5     201.               4
    #>  5 1636-69-… hyper lv2            0                 0        NA                0
    #>  6 1636-69-… hypo  lv1_…          0.468            15        68.1              3
    #>  7 1636-69-… hyper lv1_…          0.623            57.5     201.               4
    #>  8 1636-69-… hypo  lv1            0                 0        NA                0
    #>  9 1636-69-… hypo  lv2            0                 0        NA                0
    #> 10 1636-69-… hypo  exte…          0                 0        NA                0
    #> # ℹ 123 more rows

## cgmguru: detect_all_events

    all_events_5 <- detect_all_events(example_data_5_subject)
    print(all_events_5)
    #> $subject_summary
    #> # A tibble: 5 × 24
    #>   id          TIR  TITR TBR70 TBR54 TAR180 TAR250    CV    SD mean_glucose   GMI
    #>   <chr>     <dbl> <dbl> <dbl> <dbl>  <dbl>  <dbl> <dbl> <dbl>        <dbl> <dbl>
    #> 1 Subject 1  91.7 73.7   0.14  0      8.2    0.38  26.9  33.3         124.  6.27
    #> 2 Subject 2  26.4  3.36  0     0     73.6   26.1   24.0  52.4         218.  8.54
    #> 3 Subject 3  81.3 49.8   0.33  0     18.3    5.68  29.1  44.8         154.  6.99
    #> 4 Subject 4  95.1 67.7   0.27  0.05   4.61   0     22.4  29.1         130.  6.41
    #> 5 Subject 5  62.1 30.1   0.1   0     37.8   11.3   33.6  58.6         175.  7.49
    #> # ℹ 13 more variables: uGMI <dbl>, GRI <dbl>, sensor_wear_percent <dbl>,
    #> #   hypo_lv1_total_episodes <int>, hypo_lv2_total_episodes <int>,
    #> #   hypo_extended_total_episodes <int>, hypo_lv1_excl_total_episodes <int>,
    #> #   hypo_rebound_total_episodes <int>, hyper_lv1_total_episodes <int>,
    #> #   hyper_lv2_total_episodes <int>, hyper_extended_total_episodes <int>,
    #> #   hyper_lv1_excl_total_episodes <int>, hyper_rebound_total_episodes <int>
    #>
    #> $glycemic_event_summary
    #> # A tibble: 50 × 6
    #>    id        type  level    total_episodes avg_ep_per_day avg_minutes_below_54…¹
    #>    <chr>     <chr> <chr>             <int>          <dbl>                  <dbl>
    #>  1 Subject 1 hypo  lv1                   1           0.09                      0
    #>  2 Subject 1 hypo  lv2                   0           0                         0
    #>  3 Subject 1 hypo  extended              0           0                         0
    #>  4 Subject 1 hypo  lv1_excl              1           0.09                      0
    #>  5 Subject 1 hypo  rebound               0           0                         0
    #>  6 Subject 1 hyper lv1                  16           1.44                      0
    #>  7 Subject 1 hyper lv2                   2           0.18                      0
    #>  8 Subject 1 hyper extended              0           0                         0
    #>  9 Subject 1 hyper lv1_excl             14           1.26                      0
    #> 10 Subject 1 hyper rebound               0           0                         0
    #> # ℹ 40 more rows
    #> # ℹ abbreviated name: ¹​avg_minutes_below_54_per_episode

    all_events_hall <- detect_all_events(example_data_hall)
    print(all_events_hall)
    #> $subject_summary
    #> # A tibble: 19 × 24
    #>    id         TIR  TITR TBR70 TBR54 TAR180 TAR250    CV    SD mean_glucose   GMI
    #>    <chr>    <dbl> <dbl> <dbl> <dbl>  <dbl>  <dbl> <dbl> <dbl>        <dbl> <dbl>
    #>  1 1636-69…  96.9  88.0  0.54  0      2.55   0     25.2  27.3        108.   5.9
    #>  2 1636-69…  99.6  86.5  0.17  0      0.28   0     17.5  20.1        115.   6.06
    #>  3 1636-69…  99.8  97.0  0.06  0      0.17   0     14.1  15.2        108.   5.9
    #>  4 1636-69…  98.1  89.8  0.91  0      1.02   0     22.0  24.0        109.   5.91
    #>  5 1636-69… 100    96.6  0     0      0      0     14.3  14.7        103.   5.78
    #>  6 1636-69… 100    94.3  0     0      0      0     14.9  16.8        113.   6.02
    #>  7 1636-70…  97.1  89.8  1.46  0.22   1.41   0     19.7  22.3        113.   6.01
    #>  8 1636-70…  97.1  85.8  2.64  0      0.27   0     19.7  22.5        114.   6.04
    #>  9 2133-004  94.3  74.7  0.73  0      5.01   0     22.6  28.7        127.   6.34
    #> 10 2133-015  97.8  94.3  1.2   0      0.98   0     17.4  18.9        109.   5.91
    #> 11 2133-017  99.8  91.3  0.06  0      0.11   0     18.8  20.6        110.   5.93
    #> 12 2133-018  88.3  80.4  0     0     11.7    1.86  31.1  39.4        127.   6.34
    #> 13 2133-019  98.4  89.7  1.44  0.06   0.11   0     21.1  22.5        107.   5.86
    #> 14 2133-021  91.3  70.7  0.61  0      8.07   0     24.7  32.1        130.   6.42
    #> 15 2133-024  93.8  91.0  6.15  0.55   0      0     20.1  20.0         99.4  5.69
    #> 16 2133-027  94.5  93.6  5.48  0      0      0     14.7  13.4         91.1  5.49
    #> 17 2133-035  99.2  95.0  0.55  0.05   0.27   0     16.6  16.9        102.   5.74
    #> 18 2133-036  93.5  82.6  5.07  0      1.43   0     24.7  26.6        108.   5.88
    #> 19 2133-039  95.1  87.3  4.22  0.15   0.7    0     22.8  23.7        104.   5.8
    #> # ℹ 13 more variables: uGMI <dbl>, GRI <dbl>, sensor_wear_percent <dbl>,
    #> #   hypo_lv1_total_episodes <int>, hypo_lv2_total_episodes <int>,
    #> #   hypo_extended_total_episodes <int>, hypo_lv1_excl_total_episodes <int>,
    #> #   hypo_rebound_total_episodes <int>, hyper_lv1_total_episodes <int>,
    #> #   hyper_lv2_total_episodes <int>, hyper_extended_total_episodes <int>,
    #> #   hyper_lv1_excl_total_episodes <int>, hyper_rebound_total_episodes <int>
    #>
    #> $glycemic_event_summary
    #> # A tibble: 190 × 6
    #>    id          type  level  total_episodes avg_ep_per_day avg_minutes_below_54…¹
    #>    <chr>       <chr> <chr>           <int>          <dbl>                  <dbl>
    #>  1 1636-69-001 hypo  lv1                 3           0.47                      0
    #>  2 1636-69-001 hypo  lv2                 0           0                         0
    #>  3 1636-69-001 hypo  exten…              0           0                         0
    #>  4 1636-69-001 hypo  lv1_e…              3           0.47                      0
    #>  5 1636-69-001 hypo  rebou…              0           0                         0
    #>  6 1636-69-001 hyper lv1                 4           0.62                      0
    #>  7 1636-69-001 hyper lv2                 0           0                         0
    #>  8 1636-69-001 hyper exten…              0           0                         0
    #>  9 1636-69-001 hyper lv1_e…              4           0.62                      0
    #> 10 1636-69-001 hyper rebou…              0           0                         0
    #> # ℹ 180 more rows
    #> # ℹ abbreviated name: ¹​avg_minutes_below_54_per_episode

## Speed comparison

We compare performance using `microbenchmark` on both datasets. Each benchmark contrasts `iglu::episode_calculation()` with `cgmguru::detect_all_events()`.

    library(microbenchmark)
    library(iglu)

    # example_data_5_subject
    bench_5 <- microbenchmark(
      episode_calculation = iglu::episode_calculation(example_data_5_subject),
      detect_all_events   = cgmguru::detect_all_events(example_data_5_subject),
      times = 10,
      unit = "ms"
    )
    print(bench_5)
    #> Unit: milliseconds
    #>                 expr        min         lq       mean     median         uq
    #>  episode_calculation 286.153186 291.354528 296.443887 292.961585 295.251373
    #>    detect_all_events   2.909934   3.087095   3.114032   3.117292   3.187914
    #>         max neval cld
    #>  332.651204    10  a
    #>    3.207594    10   b

    # example_data_hall (all subjects)
    bench_hall <- microbenchmark(
      episode_calculation = iglu::episode_calculation(example_data_hall),
      detect_all_events   = cgmguru::detect_all_events(example_data_hall),
      times = 10,
      unit = "ms"
    )
    print(bench_hall)
    #> Unit: milliseconds
    #>                 expr        min        lq      mean     median        uq
    #>  episode_calculation 805.414496 811.25093 841.21055 823.232092 885.86953
    #>    detect_all_events   8.324435   8.65592  15.83776   8.830949   9.02041
    #>        max neval cld
    #>  899.40306    10  a
    #>   77.10513    10   b

    cat("Note: Installed 'iglu' version has a different 'episode_calculation' API; iglu examples are skipped.\n")

## References

- Broll S, Urbanek J, Buchanan D, Chun E, Muschelli J, Punjabi N, and Gaynanova I. Interpreting blood glucose data with R package iglu. PLoS One. 2021;16(4):e0248560. doi:10.1371/journal.pone.0248560.
- Chun E, Fernandes JN, and Gaynanova I. An Update on the iglu Software Package for Interpreting Continuous Glucose Monitoring Data. Diabetes Technology & Therapeutics. 2024;26(12):939-950. doi:10.1089/dia.2024.0154.
- iglu package site and citation guidance: https://irinagain.github.io/iglu/ and https://irinagain.github.io/iglu/authors.html.