.. currentmodule:: taurus.qt.qtgui.plot

.. _taurusplot_ui:

============================
TaurusPlot User's Interface
============================

.. contents::


The standard way for Taurus applications to show one-dimensional data is by
using a :class:`TaurusPlot` widget.
    
:class:`TaurusPlot` is shown as an area with X and Y axes where curves (data sets)
are plotted. It may also show a legend.

.. figure:: /_static/taurusplot04.png
  :align: center

But the :class:`TaurusPlot` does a lot more than just showing a plot. It allows
the user to interact with the plot in many ways as described below.

.. note:: The features described here are available *by default* in all TaurusPlot 
          widgets, but certain GUIs may choose to disable some of these features.

.. _standalonetaurusplot:

TaurusPlot as a Stand-alone application
---------------------------------------

You may also use :class:`TaurusPlot` as a stand-alone application for displaying
attributes from the control system or for plotting a function. You can launch the
stand-alone :class:`TaurusPlot` with the following command::

    taurus qwt5 plot [options] [<model_list>]
	
Run the following command for more details::

    taurus qwt5 plot --help

The <model_list> is a space-separated list of models for :class:`TaurusPlot`. Valid models are:
SPECTRUM attribute names or alias, and `Xattrname|Yattrname` constructions for indicating X-Y scatter plots.
See :class:`TaurusPlot` API for more information about valid models

Working with two Y scales
-------------------------

A :class:`TaurusPlot` has a X axis and one or two Y axes (left and right, also
called Y1 and Y2 and drawn in black and blue, respectively).
Multiple curves can be displayed simultaneously and each one will be associated
to either Y1 or Y2.

By default, :class:`TaurusPlot` only shows a legend when more than one curve is displayed
(this behavior can be overridden using the `TaurusPlot context menu`_).

Curves associated to the Y1 axis show their title in the legend using black text,
while those associated to Y2 use blue text.

You can change the axis to which a curve is associated by clicking on its title
in the legend. There are three states: associated to Y1 (black legend text),
associated to Y2 (blue legend text), and hidden (the curve is not displayed
and its title in the legend becomes gray).

You can also change the axis to which a curve is associated using the
`Plot Configuration dialog`_.

.. _taurusplotcontextmenu:

TaurusPlot context menu
-----------------------

Most of the options of a :class:`TaurusPlot` can be managed from a context menu that is
shown when right clicking on the plot area:

.. figure:: /_static/taurusplot-context01.png
   :align: center

Right-clicking on an axis will show a context menu with the specific options
for that axis.

Zooming and panning
-------------------

There are several ways of changing the scales interactively:

- The plots can be zoomed in and out by using the mouse wheel over the plot area.
- Zooming over selected areas is also possible by dragging a selection rectangle
  with the left button of the mouse. Right-clicking will go back to the
  previous selection. Note that, if both Y1 and Y2 axes are enabled, the zooming
  region will only affect the curves attached to one of the axes (the region
  selector will be black when the active axis is Y1 and blue when it is Y2).
  It is possible to change which Y axis is active for zooming by either using
  the 'Z' key, or via `TaurusPlot context menu`_
- Panning (i.e. translating without scaling) is done by holding the CTRL key down
  while dragging with the left button of the mouse.
- The ESC key resets the zooms and returns to auto-scale mode.
- Finally, all details about the scales are accessible at the `Plot Configuration dialog`_.


.. _plotconfiguration:
  
Plot Configuration dialog
-------------------------

.. figure:: /_static/taurusplot-config01.png
   :align: center
   
This dialog can be accessed from the `TaurusPlot context menu`_.

On its top section you can customize the look of the displayed data (line type,
symbols used, colors, thicknesses, associated axis,...).
Any changes will be automatically applied to all the curves selected from
the list on the left.

The curve titles can be changed by editing them directly in the list (one by
one) as well as by selecting some of them and using the `Curve Title(s)...` button.

On the bottom part you can control the scales for all axes (X, Y1 and Y2):

- custom scales. If the "Custom scale" check box is enabled for an axis, the
  range defined by the min and max values will remain fixed. If it is disabled,
  the axis will auto scale to accommodate all the data.
- Axis type: You can choose either Linear or Logarithmic scales. Note:
  non-positive points will be silently ignored when in logarithmic mode.

Choosing what is plotted
------------------------
When :class:`TaurusPlot` is used in a GUI, it is likely that some data is already plotted on
it. But, say that you want to compare it against some function, or against data
stored in a file, or even against some attribute of the control system...

...then the `Input data selection` option from the `TaurusPlot context menu`_ is for you!

From the `Attributes` tab of the import data dialog, you can choose which Tango attributes are
plotted, thanks to a :ref:`TaurusModelChooser <modelchooser>` widget.

.. figure:: /_static/taurusmodelchooser01.png
   :align: center

If the data you want to plot is not an attribute, go to the `Raw Data` tab,
where you can add data sets to the plot from the following sources:

- You can read it from a file (e.g., one that was created with the `export to
  ASCII option` from the `TaurusPlot context menu`_)
- You can add it by entering a mathematical formula. :class:`TaurusPlot` will recognize many
  common functions (it evaluates the formula using a subset of numpy_ expressions).
  You can use `x` as a dependent variable, which you can set as regular steps or
  using an arbitrary expression.

Note that there is actually no way to remove RawData curve from the GUI.

.. figure:: /_static/taurusplot-inputdata02.png 
   :align: center


Storing and recovering current configuration
---------------------------------------------

Once you have customized the way the plot looks (see the
`Plot Configuration dialog`_ section), you may want to save the settings for
later use. This can be done using the `Save current settings` option from the
`TaurusPlot context menu`_.

This will save which curves should be plotted and how they should look.

You can restore those settings at any point by using the `retrieve current settings`
option from the `TaurusPlot context menu`_.

**Important:** *note that if you saved the settings of a plot which displayed
an attribute from the control system, the actual values shown when restoring the
settings will be updated with the attribute value*


Obtaining information about the plotted values
-----------------------------------------------

Sometimes you want to know more about the values being plotted. The following
features can be useful:

- Obtaining coordinates of the plot area: you can get the coordinates
  (in the X-Y1 system) for any arbitrary point of the plot by simply clicking on it.
  
  .. image:: /_static/taurusplot-datainfo01.png
  
- Data Inspector: you can inspect the value of any given data point by entering in
  *Inspector mode*. You can toggle this mode this by pressing the "I" key or via
  the `TaurusPlot context menu`_ (the cursor over the plot will change from the
  usual cross to something like this: |inspector_icon|, depending on the system).
  Once in data inspector mode, you can click on a data point, which will be
  marked and some information about it will be displayed:

  .. image:: /_static/taurusplot-datainfo02.png  

- Peak locator: :class:`TaurusPlot` can locate and put a mark at the maximum and/or minimum
  points in the plotted data. You switch this option on and off using the
  `Show min` and `Show max` option from the `TaurusPlot context menu`_ or use from the
  `Peak Markers` option in the `Plot Configuration dialog`_

  .. image:: /_static/taurusplot-datainfo03.png
  
- Finally, if you want to see a text list of all the data being plotted, you
  can also do it from the `Export to ASCII Dialog` from the `TaurusPlot context menu`_

Exporting and printing the data
-------------------------------

You want a figure for a logbook?

Or you want to store the plotted values in a file?

Then you will like the Export capabilities of TaurusPlot.

You can access them from the `TaurusPlot context menu`_ and for the moment they
allow you to:

- Print the plot.
- Create a PDF from the plot. Note that it is not a simple screenshot, but a proper
  vectorial PDF (this means you can zoom in without loosing resolution).
- Export the data values to ASCII (you can edit before saving!):
    This will save the data in plain ASCII text format.
    If the plot is showing more than one curve, you can choose between:
    
    - saving a single curve in two-column mode
    - saving all the curves in a single table-like file (this is only possible
      if the X data is the same for all curves)
    - saving all curves to separate files in one go.
  
  .. image:: /_static/taurusplot-exportascii01.png
  
  *(note that you can also use this dialog to inspect the data and to copy it to
  the clipboard)*


Customizing the titles of the curves
------------------------------------

The titles of the curves (which are displayed in the legend) can be customised
in several ways:

- Through the `Change Curves Titles...` option in the `TaurusPlot context menu`_
- Through the `Plot Configuration dialog`_ (either editing the name
  individually, or selecting several curves and clicking on the `Curve Title(s)...` button)
    
.. _taurusplottime:

Date/time support
-----------------

In some applications, the values of the X axis are interpreted as date/time
values (this is set either by the GUI using TaurusPlot, or by the `-xt` parameter if
TaurusPlot is being launched from the command line).

In this mode, the values of the abscissas must be valid epoch numbers, i.e.
seconds since the "beginning of times" (UNIX t=0 : 1970-01-01 01:00:00).
TaurusPlot will interpret such values and display well-formatted dates and times
instead of the epoch number:

.. image:: /_static/taurusplot-timesupport01.png

When working in time mode, the X axis in the `Plot Configuration dialog`_
changes to "Time", and the Min/Max entries change to Start/End, where you can
enter a date (and, optionally a time).

Here are some tips for entering valid date/time values:

- For absolute date/times:
    - The date can be written in various formats. ISO format is recommended
      (e.g. "1917-10-25"), although others like, e.g. "25/10/1917"
      are also accepted.
    - The time is given in 24 hours format (e.g. "21:45") and may optionnaly
      include seconds if given (e.g. "21:45:01")
    - Date is mandatory while time is optional. If time is given, it must be
      separated from the date with a single space (e.g. "1917-10-25 21:45:01")
    
    .. image:: /_static/taurusplot-timesupport02.png
  
- For relative date/times.
    - You can specify the date/time relative to the current time. Do this by
      using a "+" or "-" symbol, followed by a number and a time unit
      (valid time units are "s", "m", "h", "d", "w" and "y"). For example, the
      following are valid relative times: "-1d", "+3w", "- 3.6e3 s". Note that
      the units are case-sensitive (e.g., "-1D" is not valid)
    - also, the keyword "now" (case-insensitive) can be used as a synonym of
      "+0s".


.. references
.. _numpy: http://numpy.scipy.org/
.. _guiqwt: http://pypi.python.org/pypi/guiqwt


.. |inspector_icon| image:: /_static/whatsthiscursor.png