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MapAlignerSpectrum

Corrects retention time distortions between maps by aligning spectra.

potential predecessor tools $ \longrightarrow $ MapAlignerSpectrumAlignment $ \longrightarrow $ potential successor tools
FileConverter FeatureFinderCentroided
(or another feature finding algorithm)

This tool provides an algorithm to align the retention time scales of multiple input files, correcting shifts and distortions between them. Retention time adjustment may be necessary to correct for chromatography differences e.g. before data from multiple LC-MS runs can be combined (feature grouping), or when one run should be annotated with peptide identifications obtained in a different run.

All map alignment tools (MapAligner...) collect retention time data from the input files and - by fitting a model to this data - compute transformations that map all runs to a common retention time scale. They can apply the transformations right away and return output files with aligned time scales (parameter out), and/or return descriptions of the transformations in trafoXML format (parameter trafo_out). Transformations stored as trafoXML can be applied to arbitrary files with the MapRTTransformer tool.

The map alignment tools differ in how they obtain retention time data for the modeling of transformations, and consequently what types of data they can be applied to. Here, an experimental algorithm based on spectrum alignment is implemented. It is only applicable to peak maps (mzML format). For more details and algorithm-specific parameters (set in the INI file) see "Detailed Description" in the algorithm documentation.

See Also
MapAlignerIdentification MapAlignerPoseClustering MapRTTransformer

Since OpenMS 1.8, the extraction of data for the alignment has been separate from the modeling of RT transformations based on that data. It is now possible to use different models independently of the chosen algorithm. This algorithm has been tested mostly with the "interpolated" model. The different available models are:

The following parameters control the modeling of RT transformations (they can be set in the "model" section of the INI file):
NameTypeDefaultRestrictionsDescription
type stringinterpolated linear, b_spline, interpolatedType of model
linear:symmetric_regression stringfalse true, falsePerform linear regression on 'y - x' vs. 'y + x', instead of on 'y' vs. 'x'.
b_spline:num_breakpoints int5 min: 2Number of breakpoints of the cubic spline in the smoothing step. More breakpoints mean less smoothing. Reduce this number if the transformation has an unexpected shape.
b_spline:break_positions stringuniform uniform, quantilesHow to distribute the breakpoints on the retention time scale. 'uniform': intervals of equal size; 'quantiles': equal number of data points per interval.
interpolated:interpolation_type stringcspline linear, cspline, akimaType of interpolation to apply.

The command line parameters of this tool are:

MapAlignerSpectrum -- Corrects retention time distortions between maps by spectrum alignment.
Version: 1.11.1 Nov 14 2013, 11:18:15, Revision: 11976

Usage:
  MapAlignerSpectrum <options>

This tool has algoritm parameters that are not shown here! Please check the ini file for a detailed descripti
on or use the --helphelp option.

Options (mandatory options marked with '*'):
  -in <files>*        Input files separated by blanks (all must have the same file type) (valid formats: 'mzM
                      L')
  -out <files>        Output files separated by blanks. Either 'out' or 'trafo_out' has to be provided. They 
                      can be used together. (valid formats: 'mzML')
  -trafo_out <files>  Transformation output files separated by blanks. Either 'out' or 'trafo_out' has to be 
                      provided. They can be used together. (valid formats: 'trafoXML')
                      
                      
Common TOPP options:
  -ini <file>         Use the given TOPP INI file
  -threads <n>        Sets the number of threads allowed to be used by the TOPP tool (default: '1')
  -write_ini <file>   Writes the default configuration file
  --help              Shows options
  --helphelp          Shows all options (including advanced)

The following configuration subsections are valid:
 - algorithm   Algorithm parameters section
 - model       Options to control the modeling of retention time transformations from data

You can write an example INI file using the '-write_ini' option.
Documentation of subsection parameters can be found in the doxygen documentation or the INIFileEditor.
Have a look at the OpenMS documentation for more information.

INI file documentation of this tool:

Legend:
required parameter
advanced parameter
+MapAlignerSpectrumCorrects retention time distortions between maps by spectrum alignment.
version1.11.1 Version of the tool that generated this parameters file.
++1Instance '1' section for 'MapAlignerSpectrum'
in[] Input files separated by blanks (all must have the same file type)input file*.mzML
out[] Output files separated by blanks. Either 'out' or 'trafo_out' has to be provided. They can be used together.output file*.mzML
trafo_out[] Transformation output files separated by blanks. Either 'out' or 'trafo_out' has to be provided. They can be used together.output file*.trafoXML
log Name of log file (created only when specified)
debug0 Sets the debug level
threads1 Sets the number of threads allowed to be used by the TOPP tool
no_progressfalse Disables progress logging to command linetrue,false
testfalse Enables the test mode (needed for internal use only)true,false
+++algorithmAlgorithm parameters section
gapcost1 This Parameter stands for the cost of opining a gap in the Alignment. A Gap means that one Spectrum can not be aligned directly to another Spectrum in the Map. This happens, when the similarity of both spectra a too low or even not present. Imagen as a insert or delete of the spectrum in the map. The gap is necessary for aligning, if we open a gap there is a possibility that an another spectrum can be correct aligned with a higher score as before without gap. But to open a gap is a negative event and has to be punished a bit, so such only in case it 's a good choice to open a gap, if the score is bad enough. The Parameter is to giving as a positive number, the implementation convert it to a negative number.0:∞
affinegapcost0.5 This Parameter controls the cost of extension a already open gap. The idea behind the affine gapcost lies under the assumption, that it is better to get a long distance of connected gaps than to have a structure gap match gap match. There for the punishment for the extension of a gap has to be lower than the normal gapcost. If the the result of the aligmnet show high compression, it is a good idea to lower the affine gapcost or the normal gapcost.0:∞
cutoff_score0.7 The Parameter defines the threshold which filtered Spectra, these Spectra are high potential candidate for deciding the interval of a sub-alignment. Only those pair of Spectra are selected, which has a score higher or same of the threshold.0:1
bucketsize100 Defines the numbers of buckets. It is a quantize of the interval of those points, which defines the main alignment(match points). These points have to filtered, to reduce the amount of points for the calculating a smoother spline curve.1:∞
anchorpoints100 Defines the percent of numbers of match points which a selected from one bucket. The high score pairs are previously selected. The reduction of match points helps to get a smoother spline curve.1:100
debugfalse active the debug mode, there a files written starting with debug prefix.true,false
mismatchscore-5 Defines the score of two Spectra if they have no similarity to each other. -∞:0
scorefunctionSteinScottImproveScore The score function is the core of an alignment. The success of an alignment depends mostly of the elected score function. The score function return the similarity of two Spectrum back. The score influence defines later the way of possible traceback. There exist many way of algorithm to calculate the score.SteinScottImproveScore,ZhangSimilarityScore
+++modelOptions to control the modeling of retention time transformations from data
typeinterpolated Type of modellinear,b_spline,interpolated
++++linearParameters for 'linear' model
symmetric_regressionfalse Perform linear regression on 'y - x' vs. 'y + x', instead of on 'y' vs. 'x'.true,false
++++b_splineParameters for 'b_spline' model
num_breakpoints5 Number of breakpoints of the cubic spline in the smoothing step. More breakpoints mean less smoothing. Reduce this number if the transformation has an unexpected shape.2:∞
break_positionsuniform How to distribute the breakpoints on the retention time scale. 'uniform': intervals of equal size; 'quantiles': equal number of data points per interval.uniform,quantiles
++++interpolatedParameters for 'interpolated' model
interpolation_typecspline Type of interpolation to apply.linear,cspline,akima

OpenMS / TOPP release 1.11.1 Documentation generated on Thu Nov 14 2013 11:19:24 using doxygen 1.8.5