Fast Average for Large Spectral Dataset

This function efficiently averages the samples spectra in a large dataset. It provides flexibility by computing either the overall mean across all spectra or group-wise means based on the values of a specified grouping column.

Usage

average(x, .group_by = NULL)

Arguments

x

A data frame or tibble.

.group_by

The column name to group the data by (optional). If not provided, the average of the overall data will be computed.

Value

• If .group_by = NULL, the function returns a numeric vector containing the mean of each column across all spectra.

• If .group_by is provided, the function returns a data frame with columns corresponding to the unique values in the grouping column. Each cell contains the mean of the corresponding column for that group.

Details

The function leverages the power of Rcpp to perform the mean calculations in C++. The underlying C++ implementation has a time complexity of O(n × m), where n is the number of rows and m is the number of columns in the data. This efficient implementation ensures that the function can handle large datasets without significant performance overhead.

The R wrapper function adds minimal overhead for argument checking and data manipulation, while leveraging the efficient C++ implementation for the core computations. The overall time complexity remains O(n × m).

Author

Christian L. Goueguel