Content

Parsing of input parameters

Parsing "on knees"

import sys
import os

def get_input_parameters() :
    nargs = len(sys.argv)
    print 'sys.argv[0]: ', sys.argv[0]
    print 'nargs: ', nargs
    # Then do something with arguments...

Use OptionParser

from optparse import OptionParser

def input_option_parser() :

    def_fname = 'spec-xppi0412-r0060-20120507-125420.198726277.txt'
    def_cols = 100

    parser = OptionParser(description='Process optional input parameters.', usage = "usage: %prog [options]")
    parser.add_option('-f', '--fname', dest='fname', default=def_fname, action='store', type='string', help='input file name')
    parser.add_option('-c', '--cols', dest='cols', default=def_cols, action='store', type='int', help='number of columns in the image array')
    parser.add_option('-v', dest='verbose', action='store_true',  help='set flag to print more details',  default=True)
    parser.add_option('-q', dest='verbose', action='store_false', help='set flag to print less details')
    (opts, args) = parser.parse_args()

    print 'opts:',opts
    print 'args:',args

    return (opts, args)

Manipulation with directories and files

Access to files in the derectory

def getListOfFilesInDir(dirname) :
    return os.listdir(dirname)

def printListOfFilesInDir(dirname) :
    print 'List of files in the dir.', dirname
    for name in os.listdir(dirname) :
        print name
    print '\n'

Parsing the pathname

        root, ext = os.path.splitext(path) # i.e. path='root-part.tail-part'
        basename  = os.path.basename(path)
        dirname   = os.path.dirname(path)
        lexist    = os.path.lexists(path)
        isfile    = os.path.isfile(path)
        isdir     = os.path.isdir(path)
        head, tail= os.path.split(path)    # i.e. path='head-part/tail-part'
...

http://docs.python.org/library/os.path.html

Useful string parsing options

http://docs.python.org/library/string.html

    string.rsplit(str, sep, maxsplit)
    string.capitalize(word)
    string.lower(s)
    start = string.find(symbolic_string, pattern)
    pattern_length = len(pattern)

http://docs.python.org/library/parser.html?

Or use more shorter methods for str object:
http://docs.python.org/library/stdtypes.html, for example:

    par_str = line[pos_eq+1:].strip(' ').rstrip('\n')

Python - useful references

Built-in functions

http://docs.python.org/library/functions.html

setattr - gives dynamic variables in python

http://docs.python.org/library/functions.html#setattr

PyQt4

How to open/close/move other GUI window?

Try to close window if its object exists, othervise - open:

    def processConfigPars(self):
        print 'processConfigPars'
        try :
            cp.confpars.guiconfigparameters.close()
        except : # AttributeError: #NameError 
            cp.confpars.guiconfigparameters = guiconfigpars.GUIConfigParameters()
            cp.confpars.guiconfigparameters.move(self.pos().__add__(QtCore.QPoint(100,330))) # window offset
            # or use self.parentWidget().pos() for combined widgets:
            # cp.guifilebrowser.move(self.parentWidget().pos().__add__(QtCore.QPoint(240,40)))
            cp.confpars.guiconfigparameters.show()

Sometime it looks like the window does not want to move in specified position...
In particular I have observed, that everything is going correct untill the w.show(). then, suddenly happens moveEvent(), which changes the self.pos(). In my case it happened because at construction of the combined window, its size was changed and it was moved in origin... Reservation of larger window size solved this problem.

How to close window and delete object?

    def closeEvent(self, event):
        try: # try to delete self object in the cp.confpars
            del cp.confpars.guiconfigparameters 
        except # AttributeError:
            pass # silently ignore

Matplotlib

In examples below we assume

fig = plt.figure(num=1, figsize=(10,10), dpi=100, facecolor='w',edgecolor='w',frameon=True)
axes = fig.add_subplot(111)
axim = axes.imshow(arrwin, interpolation='nearest', origin='bottom', aspect='auto')

How to draw histogram

axes.hist(arr, bins=100, range=(10,50), log=False) # log for vertical scale only

How to draw graphic

axes.plot(xarr1, yarr1, '-r', xarr2, yarr2,  '-g')

How to define subplot(s) with empty axes

axes  = fig.add_subplot(111)

or

axes1  = fig.add_subplot(211)        
axes2  = fig.add_subplot(212)

How to make figure with non-equal subplots

axgr = fig.add_axes([0.1,  0.64, 0.80, 0.35])
axhi = fig.add_axes([0.1,  0.14, 0.35, 0.35])
axti = fig.add_axes([0.55, 0.14, 0.35, 0.35])

or using grid:

import matplotlib.gridspec as gridspec
gs   = gridspec.GridSpec(20, 20)
# Naive direction        [  Y   ,   X ]
axsa = fig.add_subplot(gs[ 1:16,  0:14])
axsb = fig.add_subplot(gs[ 1:16, 14:19])
axsc = fig.add_subplot(gs[16:  ,  0:14])

How to set axes limits

    
axes.set_xlim((-50,50))
axes.set_ylim((-10,210))

How to draw line

import matplotlib.lines  as lines
line = lines.Line2D(arrx, arry, linewidth=1, color='r')   
axes.add_artist(line)

How to draw axis without labels

import matplotlib.ticker as mtick
axes.xaxis.set_major_formatter( mtick.NullFormatter() )

How to rotate axis labels

for label in axes.get_xticklabels() :
    label.set_rotation(60)                  # rotate by 60 degree
    label.set_horizontalalignment('center') # 'right', etc.

How to set a number of ticks along the axis

from matplotlib.ticker import MaxNLocator
axes.xaxis.set_major_locator(MaxNLocator(4))

How to change axis label position on the plot

axes.xaxis.set_ticks_position('top')
axes.yaxis.set_ticks_position('right')

How to draw a color bar as a separate sub-plot

axCB = fig.add_subplot(gs[ 0, 0:14])
colb = fig.colorbar(axim, cax=axCB, orientation='horizontal')
axCB.xaxis.set_ticks_position('top') # change position of axis labels

How draw text

plt.text(x, y, text, fontsize=7, color='k', ha='left', rotation=45)

At the edge of matplotlib and PyQt4

We assume that everything is done in our backend basis:

import matplotlib
matplotlib.use('Qt4Agg')
import matplotlib.pyplot as plt

How to get the current matplotlib figure window position on monitor

pos = fig.canvas.manager.window.pos()
print 'x,y=', pos.x(), pos.y()

How to move the matplotlib figure window in certain (x,y) position

fig.canvas.manager.window.move(x,y) # in pixels from top-left corner

How to move the matplotlib figure window on top (of all pileup windows)

fig.canvas.manager.window.activateWindow() # Makes window active
fig.canvas.manager.window.raise_()         # Moves window on top

the attribute trick is that the fig.canvas.manager.window returns the QtGui.QMainWindow, which is subclass of QtGui.QWidget with all that useful methods.

How to add figure as a widget of the QtGui

fig = plt.figure(num=None figsize=(5,10), dpi=100, facecolor='w',edgecolor='w',frameon=True)
vbox = QtGui.QVBoxLayout()
vbox.addWidget(fig.canvas)    # Wraps figure canvas in widget 
self.setLayout(vbox)

How to receive a signal in program when window is activated by the mouse click on frame ?

I do not know yet...

But, if you click on figure canvas (the region inside the window frame, use

        fig.canvas.mpl_connect('button_press_event', self.onButtonPressEvent) 

#Should be implemented something like:
    def onButtonPressEvent( self, event ):
        """Figure is picked"""
        print 'click on fig number =', event.canvas.figure.number

How to receive a signal in program when close window by the click on "X"

        fig.canvas.mpl_connect('close_event', self.onCloseEvent)

#Should be implemented something like:
    def onCloseEvent( self, event ):
        print 'close event, fig number =', event.canvas.figure.number

How to close figure from program call

plt.close( num ) # close figure with known number num
...
plt.close('all') # close all figures

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Python, matplotlib, and PyQt4 tricks