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Applies to mineXpert 5.8.0

3 JavaScript-based Scripting

When mining data, often, the user finds herself repeating tasks time and time again. Scripting allows to craft text files in which the user writes commands that are then run by the software program one after the other.

mineXpert makes a scripting environment available to the user. That environment is materialized by a window, shown on Figure 3.1, “Scripting console, scripting tab”.

Scripting console, scripting tab
Figure 3.1: Scripting console, scripting tab

The left panel is a tree view listing all the objects or function names that are made available to the scriptor. The right panel has three tabs. The Scripting tab has two sections; the upper section is where the scripting engine output is recorded; the lower section (empty in the figure) is the actual console where the user enters the script text.

3.1 Using the scripting console

The scripting console is a multiline text edit widget. The user may enter multiple lines in that widget, using the carriage Return key. Once all the lines have been entered to make one or more complete JavaScript statements, the whole set of lines is executed by pressing the CtrlReturn key combination.

Upon execution of the script statements, any output is recorded in the upper section. When the output obtained from the engine evaluates to true, it is recorded in green color, if it evaluates to undefined, its color is black, and if it evaluates to error, it is colored in red.

Looking at the script engine output section, it is possible to read indented text, colored in grey. These are comments that mineXpert provides when it runs script statements itself as part of making available to the user globally accessible objects. For example Make available the console window under name "consoleWnd" is an explanatory text for the script statement[8] that creates a globally accessible object for the scriptor to use if necessary. The consoleWnd object that is created is listed in the tree view in the left panel of the window.

3.2 The available objects list

The left panel of the scripting window lists objects that are made available by mineXpert to the scriptor. The main objects that mineXpert makes available are shown in Figure 3.1, “Scripting console, scripting tab”

  • mainWindow: the window of the program, where the File menu resides;

  • consoleWnd: the console window where the various feedback messages to the user are displayed;

  • ticChromWnd: the window where all the total ion current chromatograms are shown;

  • massSpecWnd: the window displaying all the mass spectra;

  • driftSpecWnd: the window displaying all the drift spectra;

  • colorMapWnd: the window showing all the mz=f(dt) color maps;

  • xicExtractionWnd: the window displaying the XIC integration parameters;

  • mzIntegrationParamsWnd: the window displaying the m/z integration parameters;

  • sqlMassDataSlicerWnd: the window displaying the mass data file slicer configuration;

  • openSpectraDlg: the window listing all the currently opened mass spectrometry data files;

  • scriptingWnd: the window where all the scripting occurs.

All the items listed above are systematically made available upon launching of the application. For some, they are of no use until a new mass spectrometry file is loaded. Upon opening of a mass spectrometric data file, new objects are created that are made available and listed in this same treeview. For example, upon loading of a mass spectrometry data file, a total ion current chromatogram is computed by mineXpert and displayed in a TicChromPlotWidget object that is made available under the ticChromWnd object in the tree view. If the data file were for ion mobility mass spectrometry, a mz = f(dt) color map would be computed also and made available as a new plot widget object under the colorMapWnd object in the tree view.

When a given object is used for scripting, a shortcut to writing its name in the scripting editor is to simply double-click its item in the treeview and the name will be copied into the scripting editor.

3.3 The scripting history list

Each time a JavaScript statement (single- or multi-line) is executed, that statement gets stored in the History tab that contains a list, as shown in Figure 3.2, “Scripting console, history tab”.

Scripting console, history tab
Figure 3.2: Scripting console, history tab

The items in the history list are reusable by double-clicking on them (or selecting them and hitting Return). By doing so, the selected items are copied to the Scripting tab, in the script input widget. It is then only required to hit CtrlReturn to execute the script line(s).

Note that the history list might become very long, and the user might want to filter the entries of the list. By typing a regular expression in the edit widget below the list and pressing Return, the user can select history items matching that expression.

3.4 Exploring the available objects' features

There are three kinds of objects that are available in the scripting environment:

  • High-level graphical user interface objects that are semi-automatically made available to the JavaScript environment by the Qt libraries. These objects are not fully scriptable and comprise the highest-level windows that are automatically made available upon running the program as top level branches of the tree view in the left panel of the scripting window;

  • Middle-level graphical user interface objects that are created on demand, like the various plot widgets that are created to display data. These objects have a useful range of features, typically listed in the upper pane of the scripting window by double-clicking their item in the tree view (see below);

  • Low-level C++ classes that are mapped to first-class JavaScript objects (with support for the JavaScript new constructor operator, for example) such that they expose their full functionality to the scripting environment. The methods of these classes are described in detail in the JavaScript reference section number Chapter 4, JavaScript Reference.

The functional capabilities of the various objects listed in the tree view can be explored by using the following combination: Ctrlleft mouse button. The list of functional capabilities is printed in the script output widget, as shown in Figure 3.3, “Scripting console, checking object methods”.

Scripting console, checking object methods
Figure 3.3: Scripting console, checking object methods

As shown in the figure, the mainWindow has a number of member functions that can be called according to the conventional <object>.<function> notation. For example, entering mainWindow.quit() in the script input text widget will trigger the quit() function of the mainWindow object, effectively quitting the application (the mainWindow is actually the main mineXpert window).

Calling mainWindow.jsCreateMassSpectrumFromClipboard(), for example, will create a new mass spectrum on the basis of data presently in the clipboard, if the data are in the conventional x<sep>y format, with x, the m/z value; y, the intensity and <sep> any character that is neither a cipher nor a dot (decimal separator).

Caution
Caution

It is essential to understand that not all functions are of use in the scripting context. This is because the listing of the functional capabilities of the objects also comprise functions that are not aimed at the scripting environment but are for internal Qt or mineXpert use.

Each time a new plot widget is created during a data mining session, the matching JavaScript object is add to the tree view shown in Figure 3.3, “Scripting console, checking object methods”. The name matches the kind of plot widget, like ticChromPlotWidget0, massSpecPlotWidget0 or driftSpecPlotWidget0. The creation of these plot objects is discussed in the section below.

Another way to iterate in the JavaScript properties of the objects made available in the JavaScript environment is by using the following JavaScript code (using massSpecPlotWidget0 as an example object):


for (var prop in massSpecPlotWidget0)
print("prop: " + prop)

This bit of JavaScript code is particularly useful to explore the various functions that are available for any given C++ object that is exported to the JavaScript environment (the GlobalObject, really).

3.5 The JavaScript reference

The JavaScript reference material related to all the classes available in the JavaScript environment is located in the form of formatted plain text in the JS reference tab of the scripting window (Figure 3.4, “Scripting console, JavaScript reference tab”).

Scripting console, JavaScript reference tab

The reference tab displays all the JavaScript-related documentation that is extracted automatically from the source code. This documentation describes all the JavaScript classes available to the scripting environment. The description details the members and the methods of the class.

Figure 3.4: Scripting console, JavaScript reference tab

The line edit widget at the bottom of the tab provides an easy means to filter the documentation such that only the matching lines are displayed in the text widget. To filter the documentation, enter a regular expression (or a simple text) and press the Return key. To displays the original contents anew, remove the regular expression and press the Return key.

Tip
Tip

Sometimes, some context around the matching lines might be desirable. The number of lines upstream and downstream of the matching lines that need to be output can be defined with the Context lines spin box. A value of 0 indicates that only the matching lines are output. A value of 5 indicates that five lines above the matching line and below that matching line are output.

That JavaScript reference is also available in identical form in the JavaScript reference chapter Chapter 4, JavaScript Reference.

3.6 Creation of plot objects as a result of data mining

When new plots are created as a result of the user making data mining operations, new JavaScript objects are created. The JavaScript objects mirror the C++ objects that live in the guts of mineXpert. The convention is to name the plot objects made available to the scripting environment using an index, like in ticChromPlotWidget0, ticChromPlotWidget1… For example, when a new mass spectrometry data file is loaded, mineXpert automatically computes the TIC chromatogram and makes it available to the scripting environment under object name ticChromPlotWidget0. That name is listed as a child of the ticChromWnd object in the tree view of the available objects. This object will remain available as long as the plot lives in the ticChromWnd. Note that simulateanously, the lastTicChromPlotWidget alias is provided to the scriptor to capture that newly created object. The scriptor willing to store the name of a newly created plot can thus make an assignment like in the following code:


mainWindow.openMassSpectrometryFile("massSpecFile1.mzml");

// The last TIC chromatogram plot is made available under the
// temporary name lastTicChromPlotWidget, take advantage to store it
// under a meaningful name for later use

msFile1TicPlot = lastTicChromPlotWidget

// Open a new file so that comparisons can be made
// against the previous one

mainWindow.openMassSpectrometryFile("massSpecFile2.mzml");

// The lastTicChromPlotWidget is made available, take advantage to store
// it under a meaningful name for later use

msFile2TicPlot = lastTicChromPlotWidget

// Now it is possible to reference the two TIC chromatograms
// with their new names:

msFile1TicPlot.integrateToMz(4.5, 7);
msFile2TicPlot.integrateToMz(4.5, 7);

3.7 JavaScript-oriented classes

At the time of writing, there are a number of C++ classes that have a full JavaScript counterpart: DataPoint, Trace, MassSpectrum, MzIntegrationParams, SavGolFilter, for example. In the following sections, a number of use cases are detailed to give the reader a flavor of what is scriptable in mineXpert. Note that the classes are detailed in the scripting reference section Chapter 4, JavaScript Reference.

3.7.1 Creating a DataPoint object

The C++ class DataPoint has two member data: m_key and m_val. Both are high precision double values. The JavaScript counter part is also named DataPoint and can be initialized in two ways:


// create a new DataPoint object, initialized using double values
var dp1 = new DataPoint(123.321,456.654);

// check that this worked fine:
dp1.key;
// --> returns 123.321 (same as dp1["key"])
dp1.val;
// --> returns 456.654 (same as dp1["val"])

dp1.isValid();
// --> returns true

// create a new DataPoint object, initialized using an xy-formatted string
var dp2 = new DataPoint("147.741 258.852");

// check that this worked fine:
dp2.key;
// --> returns 147.741
dp2.val;
// --> returns 258.852

dp2.isValid();
// --> returns true

// create an empty DataPoint object
var dp3 = new DataPoint()

// an empty DataPoint object is invalid
dp3.isValid();
// --> returns false

// a DataPoint can be initialized a posteriori
dp1.initialize(159.951, 357.753)

// or using a string
dp2.initialize("258.852 741.147");

The DataPoint class is the main building block Trace objects are made of. A Trace object is nothing but a list of DataPoint instances.

3.7.2 Creating Trace objects

A JavaScript Trace object is nothing but an array of DataPoint objects. One useful application of scripting is to perform a variety of calculations on a given Trace or on a set of Trace\_s.

A JavaScript Trace object can be created and initialized in a number of ways.

3.7.2.1 Creating an empty Trace and initializing it



// create a new Trace using an xy-formatted string
var t1 = new Trace("This is the title of the trace object");
t1.title
// --> returns This is the title of the trace object

t1.initialize("123.321 456.654\n789.987 147.741\n258.852 369.963");
// --> returns 3 // the number of created DataPoint objects

// check that the trace has effectively 3 items:
t1.length
// --> returns 3

// check that the initialization was ok
print("(" + t1[0 ].key + "," + t1[0].val + ")")
// --> returns (123.321,456.654)

// create a new Trace using two arrays of numbers (key list and value list)
var t2 = new Trace();
t2.initialize([123.321,456.654,789.987],[147.741,258.852,369.963])
// --> returns 3 (the number of created DataPoint objects)

// check actual length
t2.length
// --> returns 3

// check that the initialization went fine
t2[0].key
// --> returns 123.321
t2[0].val
// --> returns 147.741

// get the key and value lists
t2.keyArray()
// --> returns 123.321,456.654,789.987
t2.valArray()
// --> returns 147.741,258.852,369.963

// once a Trace has been initialized, it can undergo interesting actions:

// calculate the sum of all the values:
t2.valSum()
// --> returns 776.556

// a Trace object can combine into itself another Trace object
t2.combine(t1)

// now check if the t2 values have increased accordingly
t2.valArray()
// --> returns 604.395,369.963,258.852,517.704 // correct combination

// now subtract t2 from t2:
t2.subtract(t2)

// now check that subtraction worked fine
t2.valArray()
// --> returns 0,0,0

// it is possible to initialize a trace with limitation to a given key range
var t3 = new Trace()
t3.initializeRange([123.321,456.654,789.987], [147.741,258.852,369.963], 200, 500);

// there should be only one DataPoint in t3
t3.length
// --> returns 1
t3.keyArray();
// --> returns 456.654

3.7.2.2 Creating a Trace object starting from a plot

A Trace object can be easily created by using data already obtained from using mineXpert. For example, a Trace object can be made so that it reproduces a plot dispalyed in the graphical user interface. The process is shown below:



// load mobility data file
mainWnd.openMassSpectrometryFile(``mobility.mzml'')

// integrate over the full TIC chromatogram range
// creates the  massSpecPlotWidget0 object

ticChromPlotWidget0.integrateToMz()

// create a new Trace JavaScript object
var t0 = new Trace()

// now initialize t0 with the plot data of ticChromPlotWidget0
t0.initialize(massSpecPlotWidget0.keys(),massSpecPlotWidget0.values());

// check that the initialization actually worked
t0.length // should return the number of DataPoint objects in that Trace

// load a blank data file that acts as a baseline data file
mainWnd.openMassSpectrometryFile(``mobility-blank.mzml'')

// integrate over the full TIC chromatogram range
// creates the massSpecPlotWidget1 object

ticChromPlotWidget1.integrateToMz()

// create Trace JavaScript object
var t1 = new Trace()

// now initialize t1 with the plot data of ticChromPlotWidget1
t1.initialize(massSpecPlotWidget1.keys(),massSpecPlotWidget1.values());

// check that the initialization actually worked
t1.length // should return the number of DataPoint objects in that Trace

// finally perform some useful task: subtract noise from t0
t0.subtract(trace1)

// Trace object t0 now has the baseline removed.

3.7.3 Exporting a Trace object to a file

It is possible at each moment to export a given Trace object (or plot) to a file. This is possible either at the JavaScript Trace object level:



mainWnd.openMassSpectrometryFile("mobility.mzml")
ticChromPlotWidget0.integrateToMz()
var t0 = new Trace()
t0.initialize(massSpecPlotWidget0.keys(),massSpecPlotWidget0.values());
t0.exportToFile("/home/rusconi/demo.xy");

Or, at the plot level:



mainWnd.openMassSpectrometryFile("mobility.mzml")
ticChromPlotWidget0.integrateToMz()

// note how the export function name has Plot in it.
massSpecPlotWidget0.exportPlotToFile("/home/rusconi/demobis.xy");

At this point both files demo.xy and demobis.xy are bit-by-bit identical.

3.7.4 Plotting a JavaScript Trace object to a plot widget window

It is necessary for the data miner to be able to look at her data graphically. Nobody wants to scrutinize data in ASCII files. Anytime the scriptor has a Trace object, she can plot it in the window that makes sense for the data. For example, if a plot derives from mass spectral data, then logically, the new plot should derive for these mass spectral data, as exemplified below:



mainWnd.openMassSpectrometryFile("mobility.mzml");
ticChromPlotWidget0.integrateToMz();

var t1 = new Trace();
t1.initialize(massSpecPlotWidget0.keys(), massSpecPlotWidget0.values());

// and now plot that Trace object as a descendant of massSpecPlotWidget0.
// if massSpecPlotWidget0 is removed, then the descendant will be removed also
massSpecPlotWidget0.newPlot(t1);

Displaying a new plot using the <existingPlot Object>.newPlot(<Trace>) call occurs in the window that matches the type of <existingPlot>. If <existingPlot> is a mass spectrum, then the descendant plot will be displayed in the Mass~Spectrum~Window.

Any of the plot widget windows can receive a new plot according to the mechanics described above.

3.7.5 Printing a JavaScript Trace object to the console

It is possible to have a look at the numerical data of a Trace object like so:



mainWnd.openMassSpectrometryFile("mobility.mzml");
ticChromPlotWidget0.integrateToMz();

var t1 = new Trace();
t1.initialize(massSpecPlotWidget0.keys(), massSpecPlotWidget0.values());

// print the data to the console
t1.asText()

// outputs a series of xy-formatted lines like so:
// 2504.3185084749 1262.0000000000
// 2504.3503266026 1277.0000000000
// ...

// doing this is also possible at the plot widget level
// note the function name change
massSpecPlotWidget0.asXyText()

3.7.6 Running a JavaScript script from file

It is possible to run a script directly from file by using either the following flag to the mineXpert command line:

minexpert -j <scriptFile>

or by using the File -> Run a JavaScript from file menu of the scripting window. In that case the script is immediately run and the results are printed in the upper part of the Scripting tab of the scripting window.



[8] That statement was not entered by the user because it is run in the guts of mineXpert.

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