Per viewpoint the significant interactions are detected based on the background model. Each viewpoint file gets as output a file with all recorded significant interactions and a target file. The target file is especially in the batch mode context useful, it merges for two consecutive listed control and treatment viewpoint the significant interactions which can then be used to test for a differential interaction scheme.

chicSignificantInteractions supports two modes to detect significant interactions, either by an x-fold over the average background or a loose p-value. In both cases neighboring significant peaks are merged together and an additional p-value based on the sum of interactions for this neighborhood is computed. Only interactions with a higher p-value as specified by the threshold –pValue are accepted as a significant interaction.

An example usage is for single mode is:

$ chicSignificantInteractions –interactionFile interactionFilesFolder/Sox17_FL-E13-5_chr1_1000_2000.bed –referencePoints referencePointsFile.bed –range 20000 40000 –backgroundModelFile background_model.bed –loosePValue 0.5 –pValue 0.01

An example usage is for batch mode is:

$ chicViewpointBackgroundModel –matrices –referencePoints referencePointsFile.bed –range 20000 40000 –outFileName background_model.bed

The main difference between single mode and batch mode is that in single mode the parameter –interactionFile is interpreted as a list of viewpoint files created with chicViewpoint, whereas in batch mode only one file is allowed which contains per line the file names of viewpoint files. This file is created by chicViewpoint and the parameter –writeFileNamesToFile. Please have in mind to specify in batch mode the folder via –interactionFileFolder where chicViewpoint wrote the files to.

usage: chicSignificantInteractions --interactionFile INTERACTIONFILE
                                   [INTERACTIONFILE ...] --pValue PVALUE
                                   (--xFoldBackground XFOLDBACKGROUND | --loosePValue LOOSEPVALUE)
                                   --backgroundModelFile BACKGROUNDMODELFILE
                                   --range RANGE RANGE
                                   [--outFileNameSuffix OUTFILENAMESUFFIX]
                                   [--interactionFileFolder INTERACTIONFILEFOLDER]
                                   [--targetFolder TARGETFOLDER]
                                   [--outputFolder OUTPUTFOLDER]
                                   [--writeFileNamesToFile WRITEFILENAMESTOFILE]
                                   [--targetFileList TARGETFILELIST]
                                   [--batchMode] [--threads THREADS]
                                   [--fixateRange FIXATERANGE]
                                   [--xFoldMaxValueNB XFOLDMAXVALUENB]
                                   [--peakInteractionsThreshold PEAKINTERACTIONSTHRESHOLD]
                                   [--resolution RESOLUTION]
                                   [--computeSampleNumber COMPUTESAMPLENUMBER]
                                   [--help] [--version]

Named Arguments

--xFoldBackground, -xf

Filter x-fold over background. Used to merge neighboring bins with a broader peak but less significant interactions to one peak with high significance. Used only for pValue option.

--loosePValue, -lp

loose p-value threshold value to filter target regions in a first round. Used to merge neighboring bins with a broader peak but less significant interactions to one peak with high significance. Used only for pValue option.

Required arguments

--interactionFile, -if

path to the interaction files which should be used for aggregation of the statistics.

--pValue, -p

p-value threshold value to filter target regions to include them for differential analysis.

--backgroundModelFile, -bmf

path to the background file which is necessary to compute the rbz-score


Defines the region upstream and downstream of a reference point which should be included. Format is –region upstream downstream

Optional arguments

--outFileNameSuffix, -suffix

File name suffix to save the results, prefix is the input file name.

Default: “_significant_interactions.bed”

--interactionFileFolder, -iff

Folder where the interaction files are stored in. Applies only for batch mode.

Default: “.”

--targetFolder, -tf

Folder where the target files are stored.

Default: “targetFolder”

--outputFolder, -o

Output folder of the files significant interaction files.

Default: “significantFiles”

--writeFileNamesToFile, -w

Default: “significantFilesBatch.txt”

--targetFileList, -tl

The file to store the target file names.

Default: “targetList.txt”

--batchMode, -bm

The given file for –interactionFile and or –targetFile contain a list of the to be processed files.

Default: False

--threads, -t

Number of threads. Using the python multiprocessing module.

Default: 4

--fixateRange, -fs

Fixate range of backgroundmodel starting at distance x. E.g. all values greater 500kb are set to the value of the 500kb bin.

Default: 500000

--xFoldMaxValueNB, -xfnb

x-fold factor to increase the number of precomputed p-values per relative genomic distance. If set to 1, the maximal distance is used.

Default: 10

--peakInteractionsThreshold, -pit

The minimum number of interactions a detected peaks needs to have to be considered.

Default: 5

--resolution, -r

Resolution of the bin in genomic units. Values are usually e.g. 1000 for a 1kb, 5000 for a 5kb or 10000 for a 10kb resolution.This value is used to merge neighboring bins.

Default: 1000

--computeSampleNumber, -csn

Number of samples to compute together. Applies only in batch mode.

Default: 2


show program’s version number and exit