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Find New Maxima Around Grid Points

Source: R/cgmguru-functions-docs.R
find_new_maxima.Rd

Identifies new maxima in the vicinity of previously identified grid points, useful for refining maxima detection in GRID analysis. This function helps improve the accuracy of peak detection by searching around known event points.

Usage

find_new_maxima(df, mod_grid_max_point_df, local_maxima_df)

Arguments

df

A dataframe containing continuous glucose monitoring (CGM) data. Must include columns:

  • id: Subject identifier (string or factor)

  • time: Time of measurement (POSIXct)

  • gl: Glucose value (integer or numeric, mg/dL)

mod_grid_max_point_df

A dataframe with column index (candidate maxima index)

local_maxima_df

A dataframe with column local_maxima (index of local peaks)

Value

A tibble with updated maxima information containing columns (id, time, gl, index) The index column contains R-based (1-indexed) row number(s) in df; thus, time == df$time[index] and gl == df$gl[index].

See also

find_local_maxima, find_max_after_hours, transform_df

Other GRID pipeline: detect_between_maxima(), find_local_maxima(), find_max_after_hours(), find_max_before_hours(), find_min_after_hours(), find_min_before_hours(), grid(), maxima_grid(), mod_grid(), start_finder(), transform_df()

Examples

# Load sample data
library(iglu)
data(example_data_5_subject)
data(example_data_hall)

# First, get grid points and local maxima
grid_result <- grid(example_data_5_subject, gap = 15, threshold = 130)
maxima_result <- find_local_maxima(example_data_5_subject)

# Create modified grid points (simplified for example)
mod_grid_indices <- data.frame(index = grid_result$episode_start$index[1:10])

# Find new maxima around grid points
new_maxima <- find_new_maxima(example_data_5_subject,
                              mod_grid_indices,
                              maxima_result$local_maxima_vector)
print(paste("Found", nrow(new_maxima), "new maxima"))
#> [1] "Found 9 new maxima"

# Analysis on larger dataset
large_grid <- grid(example_data_hall, gap = 15, threshold = 130)
large_maxima <- find_local_maxima(example_data_hall)
large_mod_grid <- data.frame(index = large_grid$episode_start$index[1:20])
large_new_maxima <- find_new_maxima(example_data_hall,
                                    large_mod_grid,
                                    large_maxima$local_maxima_vector)
print(paste("Found", nrow(large_new_maxima), "new maxima in larger dataset"))
#> [1] "Found 20 new maxima in larger dataset"