Sample parameter points – prof-sampleparams

prof-sampleparams samples parameter points either randomly to use them as anchor points for MC data production or along straight lines for line-scan validation with prof-scanchi2.

Random mode

In the random mode (default) the points are sampled randomly from a hyper-cube. The path to the range file must be given as first argument. Alternatively, two arguments are accepted with files containing the lower and upper parameter bounds. The number of points is controlled with -N NUMRUNS. The parameter points are written to files in numbered directories under OUTDIR (see -o):

OUTDIR/000/used_params
       001/used_params
       ...

The first run number can be set with --first-run NUMFIRSTRUN. See Oversampling ratio for some comments on how many runs one should generate.

Line scan mode

Line scan mode can be activated with -s. In line scan mode equally distant points are generated along a straight line. prof-scanchi2 compares the MC data at this points with the prediction of polynomial parameterisations.

The points are only sampled from the ranges given by the first argument. These ranges should be the same that were used for the polynomials with prof-interpolate, or smaller, because otherwise the polynomials are evaluated in regions of extrapolation. Alternatively, the ranges can be specified by two parameter point files.

The location and orientation of the line in parameter space is controlled with --scancenter and the orientation with --direction.

Examples

Sample 100 points randomly from the ranges in generator.ranges and create the files under mcruns/:

prof-sampleparams -N 100 -o mcruns generator.ranges

Sample 10 points along a straight line in the ranges of generator.ranges. The line is rooted at the parameter values of the first tune in the results file results.pkl and is oriented in the direction of the largest uncertainty:

prof-sampleparams -s -N 10 -o linescan --scancenter results.pkl,0 --direction shallow generator.ranges

Command-line options

The --datadir DATADIR and related options are used as normal to specify the reference data, MC runs, and interpolation objects: see the path options page.

-N NUMRUNS, --num-runs NUMRUNS

Number of generated points.

--first-run NUMFIRSTRUN

The number of the first run.

-t, --timestamp

Prepend the OUTDIR with the current date.

-T TEMPLATE, --template TEMPLATE

Replace variable in the given template files. Can be given Multiple times.

Line scan mode

-s, --scan

Turn line scan sampling on.

--scancenter SCANCENTER

The base point of the line. Can be either a parameter file or a results file. In the second case the index of the minimization result must be appended to the file name, separated by a comma, e.g:

--scancenter results.pkl,10

--direction DIRECTION

The direction of the line scan. Three values are supported:

diagonal

The line is parallel to the body diagonal.

steep, shallow

Only allowed if SCANCENTER is a result file. The line is oriented in the direction of the smallest (steep) or largest (shallow) uncertainty as was estimated during the minimization.

To make the lines symmetric around SCANCENTER :sym can be appended.