NEWS.md

In GCalignR: Simple Peak Alignment for Gas-Chromatography Data

GCalignR 1.0.3.9

• Small bug fixed that caused problems when plotting x-axis labels in gc_heatmap. An error occurred in case of two peaks that were identical when rounded to decimal places.
• Added a test for detecting inconsistently ordered retention times within samples. Retention times are expected in increasing order, starting with the lowest number. If this assumption is violated, retention times are reordered as indicated by a warning.

GCalignR 1.0.3

• Added fill = TRUE as a parameter in utils::read.table when reading data from text within internal functions. Loading GC data with utils::read.table failed in cases of missing values in a column (i.e. empty). This is the correct behaviour as missing data should always be coded explicitly by ‘NA’
• Tibbles are now coerced to data frames
• Added a new boolean parameter remove_empty for the main function align_chromatograms. If samples are empty (i.e.. no peak) this parameter allows to remove those cases from the dataset to avoid problems in post-hoc analyses. By default FALSE, i.e.. all but the blank samples are kept.
• Added a new boolean parameter permute for the functions align_chromatograms and align_peaks. This allows to change the default behaviour of random permutation of samples during the alignment and might be useful if exact replication is needed.

GCalignR 1.0.2

• The accompanying manuscript is published https://doi.org/10.1371/journal.pone.0198311 and the citation has been added
• The function beta read_empower2 allows to import HPLC data that has been generated using the EMPOWER 2 software

GCalignR 1.0.1

Bugfixes

• A bugfix was applied for handling multiple blanks correctly.
• Progressbars are removed in non-interactive R sessions

GCalignR 1.0.0

New functions implemented

• choose_optimal_reference offers an automatism to pick suitable references.
• draw_chromatograms allows to represent a peak list in form of chromatogram.
• remove_blanksallows to get rid of peaks that represent contamination after aligning a dataset
• remove_singletons allows to remove single peaks from the dataset after aligning
• merge_redundant_rows allows to merge rows that were not recognised as redundant during the alignment by increasing the threshold value for the evaluation of similarity

Algorithm

• Using pbapply, we implemented progress bars to inform the user about the progress and the estimated running time of intermediate steps in the alignment of peak lists.
• By implementing more efficient code, we were able to speed up the processing, especially picking references is faster by an order of magnitude.
• Retention times are not rounded to two decimals anymore. Calculations still capture a precision of two decimals for computational reasons.
• Within the aligned results, retention times correspond to the input values. Linear adjustments are only used internally and are documented within the Logfile accessible in the output.
• Reference samples that are used for the coarse alignment of retention times can be picked using a novel algorithm that determines the average similarity across the dataset.

warning messages

• Warnings addressing formatting issues are now more explicit and partly rephrased to avoid ambiguity.

Plots

• Added horizontal axis to barplots summarising peak numbers in plot.GCalign.
• Changed to more prominent colours in binary heatmaps with gc_heatmap.
• The function draw_chromatograms was added as another visualisation tool.

Vignettes

• We included a second vignette that explains the algorithm and the supported data in detail.

Documentation

• Helpfiles were rewritten to enhance clarity.

GCalignR documentation built on Feb. 16, 2023, 5:23 p.m.