Page History
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Parsing the pathname
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path = '/reg/d/psdm/cxi/cxif5315/calib/pnccd/pnccd-123456.data' root, ext = os.path.splitext(path) # i.e. path='root-part.tail-part' ('/reg/d/psdm/cxi/cxif5315/calib/pnccd/pnccd-123456', '.data') # or '' if something is missing basename = os.path.basename(path) # pnccd-123456.data dirname = os.path.dirname(path) # /reg/d/psdm/cxi/cxif5315/calib/pnccd lexist lexist = os= os.path.lexists(path) # False isfile = os.path.isfile(path) # False isdir = os.path.isdir(path) # False head, tail= os.path.split(path) # i.e. path='head-part/tail-part' ('/reg/d/psdm/cxi/cxif5315/calib/pnccd', 'pnccd-123456.data') # or '' if something is missing ... |
http://docs.python.org/library/os.path.html
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s = ' '.join(sys.argv) |
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Join path and name
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path_name = os.path.join(path,fname) |
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exp = 'xpptut13' if 'tut' is in exp : <do something> |
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String alignment
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msg = '%s' % (k.ljust(16)) |
Useful string parsing options
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my_string.replace("abcde","cde")
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String formatting
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s = 'some text %s %s' % (msg.ljust(30), str(val).rjust(30) |
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print 'string properties:'
print 'punctuation : ', string.punctuation
print 'digits : ', string.digits
print 'octdigits : ', string.octdigits
print 'hexdigits : ', string.hexdigits
print 'ascii_letters : ', string.ascii_letters
print 'ascii_lowercase: ', string.ascii_lowercase
print 'ascii_uppercase: ', string.ascii_uppercase
print 'lowercase : ', string.lowercase
print 'uppercase : ', string.uppercase
print 'letters : ', string.letters
print 'printable : ', string.printable
print 'whitespace : ', string.whitespace |
Time stamp
Class name
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self.__class__.__name__ |
Function name
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sys._getframe().f_code.co_name |
Function parameters
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locals() # returns (dict) of method input parameters |
Converting integer to bin(), oct(), hex() string
using built-in functions
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ival = 123456
str_bin = bin(ival)
str_oct = oct(ival)
str_hex = hex(ival) |
Time stamp
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from time import localtime, gmtime, strftime, clock, time
time_sec = time() # epoch time |
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from time import localtime, gmtime, strftime, clock, time
time_sec = time() # epoch time
def get_current_local_time_stamp(fmt='%Y-%m-%d %H:%M:%S %Z'):
return strftime(fmt, localtime())
def get_current_gm_time_stamp(fmt='%Y-%m-%d %H:%M:%S %Z'):
return strftime(fmt, gmtime())
def get_local_time_str(time_sec, fmt='%Y-%m-%d %H:%M:%S %Z'):
return strftime(fmt, localtime(time_sec))
def get_gm_time_str(time_sec, fmt='%Y-%m-%d %H:%M:%S %Z'):
return strftime(fmt, gmtime(time_sec)) |
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Set PYTHONPATH
In command-line:
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import os
os.environ['PYTHONPATH'] = '/reg/neh/home1/dubrovin/LCLS/git-work/pyapps:%s' % os.environ.get('PYTHONPATH', '') |
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Replace symbols in string
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text.replace("|",":").replace("-",".")
range.replace('9999','end')
msg.replace('\n',' ') |
List of comprehension
list_of_x2 = [x*x for x in list_of_x]
list_of_x_selected = [x for x,y in zip(list_of_x, list_of_y) if y>0]
map - built-in method
)
range.replace('9999','end')
msg.replace('\n',' ') |
List of comprehension
list_of_x2 = [x*x for x in list_of_x]
list_of_x_selected = [x for x,y in zip(list_of_x, list_of_y) if y>0]
map - built-in method
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def f(x,y) :
return x if y>0 else -x
list = map(f, arrX, arrY) |
Constructor, destructor etc.
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class PeakListFile :
def __init__(self, fname) :
print 'constructor'
self.f=open(fname,'r')
def __del__(self) :
print 'destructor'
try :
self.f.close()
def __call__(self) :
print 'this is a default method of this object called as obj()' |
Polymorphism
Derived class initialization
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class Base :
def __init__(self) :
...
class Derived(Base) :
def __init__(self) :
Base.__init__(self)
# OR
super(Derived, self).__init__() |
Create/save temporary file
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import tempfile
tmp_file = tempfile.NamedTemporaryFile(mode='r+b',suffix='.tiff')
tfile = tmp_file.name |
Good example of __main__
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import sys
def test_all( |
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def f(x,y) : return x if y>0 else -x list = map(f, arrX, arrY) |
Constructor, destructor etc.
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class PeakListFile : def __init__(self, fname) : print 'constructor' self.f=open(fname,'r') def __del__(self) : print 'destructorprint _sep_, '\n%s' % sys._getframe().f_code.co_name test_ricker() test_morlet() #------------------------------ if __name__ == "__main__" : from time import time tname = sys.argv[1] if len(sys.argv) > 1 else '0' print 50*'_', '\nTest %s:' try% :tname t0_sec self.f.close= time() def __call__(self) : if tname print== 'this is a default method of this object called as obj()' |
Polymorphism
Derived class initialization
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class Base : def __init__(self) : ...0': test_all() elif tname == '1': test_ricker() elif tname == '2': test_morlet() else : print 'Not-recognized test name: %s' % tname msg = class Derived(Base) : def __init__(self) : 'End of test %s, consumed time (sec) = %.6f' % (tname, time()-t0_sec) Base.__init__(self) # OR sys.exit(msg) |
Virtualenv
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virtualenv dir-name source <directoryName>/bin/activate.csh # for tcsh # or source <directoryName>/bin/activate super(Derived, self).__init__() |
Create/save temporary file
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import tempfile
tmp_file = tempfile.NamedTemporaryFile(mode='r+b',suffix='.tiff')
tfile = tmp_file.name |
# for bash
pip install <packageName>
... work
deactivate |
Python - useful references
Built-in functions
http://docs.python.org/library/functions.html
setattr, getattr - set/get dynamic variables in python
http://docs.python.org/library/functions.html
setattr - gives dynamic variables in python
http://docs.python.org/library/functions.html#setattr
PyQt4
/library/functions.html#setattr
PyQt4
Know How
- QGraphicsScene item priority is set by setZValue(v)
- All re-implemented Event methods like {{mouseMoveEvent(self, e)}} etc. in items will get control only if QGraphicsView their default version will be called.
PyQt4 PyQt4 class references
All classes
Selected:
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fig.clear() |
Graphic
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import pyimgalgos.Graphics as gr axes.clear() axes.plot(xarr1, yarr1, '-r', xarr2, yarr2, '-g') gr.show(mode='do_not_hold') |
Histogram
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axes.clear() axes.hist(arr, bins=100, range=(10,50), log=False) # log for vertical scale only |
Image (with colorbar)
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img = axes.imshow(arr2d, interpolation='nearest', origin='bottom', aspect='auto')
img.set_clim(Amin,Amax)
cbar = self.fig.colorbar(img, orientation='vertical', \
fraction=0.1, pad=0.01, shrink=1.0, aspect=20)
# fraction - of the 2d plot occupied by the color bar
# pad - is a space between 2d image and color bar
# shrink - factor for the length of the color bar
# aspect - ratio length/width of the color bar
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Other supported formats: gif, pdf, png, jpeg, eps
eps
Check tiff file
To check tiff file format one may use command:
% identify -verbose <file-name>.tiffSave image in 16-bit TIFF file
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Use np.select
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V = np.array(...) Vmin, Vmax, Nbins1 <--- scalar valuer indarr = np...) Vmin, Vmax, Nbins1 <--- scalar valuer indarr = np.int32( factor * (V-Vmin) ) arrint32( factor * (V-Vmin) ) arr = np.select([V==Vmax, indarr<0, indarr>Nbins1], [Nbins1, 0, 0], default=indarr) |
protected division:
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def divideZeroProteced(nda_num, nda_den, val_subst_zero=0) : pro_num = np.select([nda_den==0], [val_subst_zero], default=nda_num) pro_den = np.select([Vnda_den==Vmax0], indarr<0, indarr>Nbins1], [Nbins1, 0, 0], default=indarr)[1], default=nda_den) return pro_num / pro_den |
SciPy
Import
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#!/usr/bin/env python import numpy as np from scipy.optimize import curve_fit |
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