🌐 Mailman 3 September 2016 - Python-list - python.org

Re: Expression can be simplified on list
by Piet van Oostrum Sept. 17, 2016

Sept. 17, 2016

Daiyue Weng <daiyueweng(a)gmail.com> writes: > Hi, I found that when I tried to make an equality test on empty like, > > if errors == []: > > PyCharm always warns me, > > Expression can be simplified. > > I am wondering what's wrong and how to fix this? > It is not wrong, but it can be simplified to just: if errors: This is quite usual in Python, but some people prefer the more elaborate form, or something like: if len(errors) == 0: -- Piet van Oostrum <piet-l(a)pietvanoostrum.com> WWW: http://pietvanoostrum.com/ PGP key: [8DAE142BE17999C4]

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Is there something similar to `set -v` of bash in python
by Peng Yu Sept. 17, 2016

Sept. 17, 2016

Hi, `set -v` in bash allows the print of the command before print the output of the command. I want to do the similar thing --- print a python command and then print the output of the command. Is it possible with python? -- Regards, Peng

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is it possible to adjust convex hull to draw blue line instead of green line?
by meInvent bbird Sept. 17, 2016

Sept. 17, 2016

i succeed to use code to draw green line, but green line not draw the large area, expect second uploaded picture, the blue line connect the bottom of red line graph im = img.copy() cntcounter = 0 for cnt in contours: #epsilon = 0.1*cv2.arcLength(cnt,True) #approx = cv2.approxPolyDP(cnt,epsilon,True) #peri = cv2.arcLength(cnt, True) #approx = cv2.approxPolyDP(cnt, 0.15 * peri, True) #print("len(approx)="+str(len(approx))) #if len(approx) == 2: print("approx=" + str(approx)) cntcounter = cntcounter + 1 print("here1") #x,y,w,h = cv2.boundingRect(cnt) hull = cv2.convexHull(cnt,returnPoints = True) print("here2") while im is None: time.sleep(1) if im is not None: print("here3") #cv2.rectangle(im, (x,y), (x+w, y+h), (0,255,0), 2) #cv2.imwrite("C:\\Users\\tester\\Documents\\masda"+str(cntcounter)+".png",imi) #im = cv2.line(im,(x,y),(x+w,y),(0,255,0),2) #im = cv2.line(im,(x+w,y),(x+w,y+h),(0,255,0),2) #im = cv2.line(im,(x,y+h),(x+w,y+h),(0,255,0),2) #im = cv2.line(im,(x,y),(x,y+h),(0,255,0),2) previousx = 0 previousy = 0 for c in hull: if previousx != 0 and previousy != 0 and c[0][0] != 0 and c[0][1] != 0 and abs(previousy - c[0][1]) > 10 and abs(c[0][0] - previousx) > 1: while im is None: time.sleep(1) cv2.line(im,(previousx,previousy),(c[0][0],c[0][1]),(0,255,0),2) print("") #print("previousx=" + str(previousx)) #print("previousy=" + str(previousy)) #print("c[0][0]=" + str(c[0][0])) #print("c[0][1]=" + str(c[0][1])) previousx = c[0][0] previousy = c[0][1] https://drive.google.com/file/d/0Bxs_ao6uuBDUWVBFZzVIVGotRlk/view?usp=shari… expected is https://drive.google.com/file/d/0Bxs_ao6uuBDUNGZFS2F3WnJERzA/view?usp=shari…

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Re: Where is the documentation for ','?
by Steve D'Aprano Sept. 17, 2016

Sept. 17, 2016

On Sat, 17 Sep 2016 12:05 pm, Peng Yu wrote: > Hi, > > I'm wondering where is the documentation for ',' as in the following > usage. > > x = 1 > y = 2 > x, y = y, x > > I tried help(','). But there are too many ',' in it and I don't see in > which section ',' is documented. Could anybody let me know? Thanks. As well as the other suggestions you have been given, try "Sequence Unpacking". -- Steve “Cheer up,” they said, “things could be worse.” So I cheered up, and sure enough, things got worse.

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Where is the documentation for ','?
by Peng Yu Sept. 17, 2016

Sept. 17, 2016

Hi, I'm wondering where is the documentation for ',' as in the following usage. x = 1 y = 2 x, y = y, x I tried help(','). But there are too many ',' in it and I don't see in which section ',' is documented. Could anybody let me know? Thanks. -- Regards, Peng

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Re: Where is the documentation for ','?
by Lawrence D’Oliveiro Sept. 17, 2016

Sept. 17, 2016

On Saturday, September 17, 2016 at 2:05:49 PM UTC+12, Peng Yu wrote: > x, y = y, x It’s just syntactic sugar for (x, y) = (y, x)

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Re: why this code loop forever after a draw a rectangle
by meInvent bbird Sept. 17, 2016

Sept. 17, 2016

thank you very much, it out of the loop now. because drawLine function return things i just change drawLine to rectangle, have not thought that rectangle not return thing, just edit the parameter On Saturday, September 17, 2016 at 5:26:53 AM UTC+8, MRAB wrote: > On 2016-09-16 20:14, Gary Herron wrote: > > On 09/16/2016 04:24 AM, meInvent bbird wrote: > >> im = img.copy() > >> cntcounter = 0 > >> for cnt in contours: > >> epsilon = 0.1*cv2.arcLength(cnt,True) > >> approx = cv2.approxPolyDP(cnt,epsilon,True) > >> #peri = cv2.arcLength(cnt, True) > >> #approx = cv2.approxPolyDP(c, 0.5 * peri, True) > >> #print("len(approx)="+str(len(approx))) > >> if len(approx) == 4: > >> print("approx=" + str(approx)) > >> cntcounter = cntcounter + 1 > >> print("here1") > >> x,y,w,h = cv2.boundingRect(cnt) > >> print("here2") > >> while im is None: > >> time.sleep(1) > >> if im is not None: > >> print("here3") > >> im = cv2.rectangle(im.copy(), (x,y), (x+w, y+h), (0,255,0), 2) > >> #im = cv2.line(im,(x,y),(x+w,y),(0,255,0),2) > >> #im = cv2.line(im,(x+w,y),(x+w,y+h),(0,255,0),2) > >> #im = cv2.line(im,(x,y+h),(x+w,y+h),(0,255,0),2) > >> #im = cv2.line(im,(x,y),(x,y+h),(0,255,0),2) > >> > >> > >> cv2.imwrite(r'C:\Users\tester\Documents\masda.png',im) > > > > > > These two lines: > > > > while im is None: > > time.sleep(1) > > > > are an infinite loop if im is None; > > > > > > Since you haven't told us what im (or img, contours, cv2) are, I can't > > tell how im might become None, but it does look like you (confusingly) > > use im for two different things: an img.copy() and a cv2.rectangle, > > whatever those may be. > > > > Pure guesswork: if cv2.rectangle draws a rectangle, what does it > > return? If it doesn't return anything, the line > > im = cv2.rectangle(...) > > is how im gets the value of None. > > > It looks like the OP is using OpenCV. > > You're right about cv2.rectangle; it does return None. > > The line: > > im = cv2.rectangle(im.copy(), (x,y), (x+w, y+h), (0,255,0), 2) > > makes a copy of the image im, draws a rectangle on it, and then binds > None to im. > > The copied rectangle is discarded because there's no reference to it, so > the entire line in pointless. > > It basically does the same thing as: > > im = None > > only slower!

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Looking for tips and gotchas for working with Python 3.5 zipapp feature
by Malcolm Greene Sept. 16, 2016

Sept. 16, 2016

Looking for tips or edge case gotchas associated with using Python 3.5's new zipapp feature. For those of you wondering what this feature is, see the end of this post for a brief background [1]. Two questions in particular: 1. Are there any issues with deploying scripts that sit in sub- folders beneath the directory being zipped, eg. does zipapp only support a flat folder of scripts or does it recursively zip and path sub-folders? 2. Can additional non-Python files like config files be added to a zipapp without breaking them and if so, how would your script reference these embedded files (by opening up the zipapp as a zip archive and navigating from there?). Thank you, Malcolm [1] The zipapp feature of Python 3.5 is pretty cool: It allows you to package your Python scripts in a single executable zip file. This isn't a replacement for tools like PyInstaller or Py2Exe, eg. it doesn't bundle the Python interpreter in the zip file, but it's a clean way to distribute multi-file scripts in environments where you have control over users' Python setups. Here's the manual page: zipapp — Manage executable python zip archives https://docs.python.org/3/library/zipapp.html

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Discover all non-standard library modules imported by a script
by Malcolm Greene Sept. 16, 2016

Sept. 16, 2016

Looking for suggestions on how, given a main script, discover all the non-standard library modules imported across all modules, eg. the modules that other modules import, etc. I'm not looking to discover dynamic imports or other edge cases, just the list modules loaded via "import <module>" and "from <module> import ...". I know I could write a script to do this, but certainly there must be such a capability in the standard library? Use case: Discovering list of modules to use for building a Python 3.5 zipapp distributable. Thank you, Malcolm

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How to get the source code of python function being decorated?
by Peng Yu Sept. 16, 2016

Sept. 16, 2016

Hi, See the following example, I am not able to get the source code of the actual function that does the calculation of partial_ratio. Does anybody know what is the correct way of getting the source? /tmp$ ./main.py @functools.wraps(func) def decorator(*args, **kwargs): if args[0] is None or args[1] is None: return 0 return func(*args, **kwargs) /tmp$ cat ./main.py #!/usr/bin/env python # vim: set noexpandtab tabstop=2 shiftwidth=2 softtabstop=-1 fileencoding=utf-8: import fuzzywuzzy.fuzz import inspect print inspect.getsource(fuzzywuzzy.fuzz.partial_ratio) -- Regards, Peng

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