Page History
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s = ' '.join(sys.argv) |
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)) |
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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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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
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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)) |
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',' ') |
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List of comprehension
list_of_x2 = [x*x for x in list_of_x]
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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()' |
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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__() |
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Create/save temporary file
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import tempfile
tmp_file = tempfile.NamedTemporaryFile(mode='r+b',suffix='.tiff')
tfile = tmp_file.name |
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tfile = tmp_file.name |
Good example of __main__
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import sys
def test_all() :
print _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:' % tname
t0_sec = time()
if tname == '0': test_all()
elif tname == '1': test_ricker()
elif tname == '2': test_morlet()
else : print 'Not-recognized test name: %s' % tname
msg = 'End of test %s, consumed time (sec) = %.6f' % (tname, time()-t0_sec)
sys.exit(msg) |
Virtualenv
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virtualenv dir-name
source <directoryName>/bin/activate.csh # for tcsh
# or
source <directoryName>/bin/activate # for bash
pip install <packageName>
... work
deactivate |
Python - useful references
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http://docs.python.org/library/functions.html#setattr
PyQt4
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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 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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