Choosing an Execution Mode

rfastlowess provides three execution modes for different data sizes and processing needs:

Execution mode comparison

Mode	Class	Use Case	Memory	Key Features
Batch	`Lowess`	Full dataset	Entire dataset	CI, PI, CV, GPU
Streaming	`StreamingLowess`	>100K points	Per chunk	With overlap
Online	`OnlineLowess`	Live / real-time	Sliding window	Per-point

Quick Decision Guide

Situation	Mode
Data fits in memory; needs intervals or CV	Batch
Data too large for memory or arrives in chunks	Streaming
Data arrives point-by-point in real time	Online

Batch Adapter

Standard mode for complete datasets. Supports all features.

When to Use

Dataset fits in memory
Need intervals, cross-validation, or diagnostics
Processing complete files

Example

library(rfastlowess)
set.seed(42)
x <- seq(0, 2 * pi, length.out = 100)
y <- sin(x) + rnorm(100, sd = 0.3)

model <- Lowess(
    fraction = 0.5,
    iterations = 3,
    parallel = TRUE,
    outputs = "diagnostics",
    intervals = intervals_opts(confidence = 0.90, prediction = 0.99)
)
result <- fit(model, x, y)
cat("95% CI at midpoint: [", result$confidence_lower[50], ", ",
    result$confidence_upper[50], "]\n")
#> 95% CI at midpoint: [ -0.03081586 ,  0.1081906 ]

Streaming Adapter

Process large datasets in chunks with configurable overlap.

When to Use

Dataset >100,000 points
Memory-constrained environments
Batch processing pipelines

Parameters

Parameter	Default	Description
`chunk_size`	5000	Points per chunk
`overlap`	`chunk_size / 10`	Overlap between chunks
`merge_strategy`	`"weighted_average"`	How to merge overlaps

Merge Strategies

Strategy	Behavior
`"average"`	Average overlapping values
`"weighted_average"`	Distance-weighted blend
`"take_first"`	Keep left chunk values
`"take_last"`	Keep right chunk values

Example

library(rfastlowess)
x <- seq(0, 2 * pi, length.out = 100)
y <- sin(x) + 0.1

model <- StreamingLowess(
    fraction = 0.3,
    iterations = 2,
    chunk_size = 5000,
    overlap = 500,
    merge_strategy = "average"
)
process_chunk(model, x, y)
#> <LowessResult>
#>   Points:            0 
#>   Fraction Used:     0.3 
#>   Iterations Used:   2
result <- finalize(model)
cat("Smoothed y[0]:", result$y[1], "\n")
#> Smoothed y[0]: 0.2577957

Always call finalize(): The streaming adapter buffers overlap data. Call finalize(model) after the last chunk to retrieve the buffered tail.

Online Adapter

Incremental updates with a sliding window for real-time data.

When to Use

Data arrives incrementally (sensors, streams)
Need real-time smoothed values
Fixed memory budget

Parameters

Parameter	Default	Description
`window_capacity`	1000	Max points in window
`min_points`	2	Points before output starts
`update_mode`	`"incremental"`	Update strategy

Update Modes

Mode	Behavior	Speed
`"incremental"`	Update only affected fits	Faster
`"full"`	Recompute entire window	More accurate

Example

library(rfastlowess)
x <- seq(0, 2 * pi, length.out = 100)
y <- sin(x) + 0.1

model <- OnlineLowess(
    fraction = 0.2,
    window_capacity = 100,
    min_points = 5,
    update_mode = "incremental"
)
shown <- 0
for (i in seq_along(x)) {
    result <- add_point(model, x[i], y[i])
    if (!is.null(result) && shown < 5) {
        cat("Current smoothed value:", result$y, "\n")
        shown <- shown + 1
    }
}
#> Current smoothed value: 0.351148 
#> Current smoothed value: 0.4120334 
#> Current smoothed value: 0.4716625 
#> Current smoothed value: 0.5297949 
#> Current smoothed value: 0.5861967

Feature Comparison

Feature	Batch	Streaming	Online
Parallel execution	✓	✓	✗
Diagnostics	✓	✓	✗
Residuals	✓	✓	✓
Robustness weights	✓	✓	✓
Confidence intervals	✓	✗	✗
Prediction intervals	✓	✗	✗
Cross-validation	✓	✗	✗

sessionInfo()
#> R version 4.6.1 (2026-06-24)
#> Platform: x86_64-pc-linux-gnu
#> Running under: Ubuntu 26.04.1 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-r0.3.32.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] rfastlowess_5.0.0 rmarkdown_2.32   
#> 
#> loaded via a namespace (and not attached):
#>  [1] digest_0.6.39    R6_2.6.1         fastmap_1.2.0    xfun_0.61       
#>  [5] maketools_1.3.2  cachem_1.1.0     knitr_1.52       htmltools_0.5.9 
#>  [9] buildtools_1.0.0 lifecycle_1.0.5  cli_3.6.6        sass_0.4.10     
#> [13] jquerylib_0.1.4  compiler_4.6.1   sys_3.4.3        tools_4.6.1     
#> [17] evaluate_1.0.5   bslib_0.12.0     yaml_2.3.12      otel_0.2.0      
#> [21] jsonlite_2.0.0   rlang_1.3.0