Classic Python Gotch - * on List of Lists - No No!!

[0] * 10 

is okay.

But,

initializing using

[ [0] ] * 10
So you get [ [0] , [0], ... [0] ] 
is NOT okay - you've built a list of copies of the SAME list!!!

You wouldn't guess would you? This is where Larry Wall would have dumped out a nice warning. Why can't python marry with Perl?

Contrasting Styles - Inverting an Adjacency Graph

Mine :

def inverse_graph(graph):
    invG = []
    for i,row in enumerate(graph) :
        sieve = [1] * len( row )
        sieve[i] = 0
        invG.append( [xor(x[0], x[1]) for x in zip(row, sieve)] )
    return invG

Instructor :

def inverse_graph(graph):
    n = len( graph )
    invG = []
    for i in range( n ) :
        invG.append( [] )
        for j in range( n ) :
             if i != j :
                   invG[i].append( 1 - graph[i][j] )
             else :
                   invG[i].append( 0 )
    return invG

Which do you feel is more idiomatic?

Here's a handy hack - if you had a list of ints, which is a subset of the first n non-negative ints (0,1,2,.. n-1), how do you build yourself a list of ones and zeros such that the entry is a one when the ordinal number representing that entry is in the list of ints? ( [0,1,4], 5 ) --> [ 1, 1, 0 , 0 , 1] )

sieve = list(map(lambda x: 1 if x in cover else 0, range(len(graph))))

Like?

Visual Studio Code Setup for Simple Build In Local Directory No Frills

Assuming :

You're okay with a.out, then :

{

    "tasks": [

        {

            "type": "shell",

            "label": "C/C++: g++ build active file",

            "command": "/usr/bin/g++",

            "args": [

                "-g",

                "${file}",

            ],

            "options": {

                "cwd": "${fileDirname}"

            },

            "problemMatcher": [

                "$gcc"

            ],

            "group": {

                "kind": "build",

                "isDefault": true

            },

            "detail": "Generated task by Debugger"

        }

    ],

    "version": "2.0.0"

}

Python : Access Your Own Docstring

You have a function in a file and you want to view the docstring. You're in the python shell. What's the quickest way?

> Cheat - assume you're in the same directory :)

>>> from basename import * # file is basename.py

>>> func_name.__doc__     # will show it to you

Python Assign Characters of a String to a List

Or, convert a string to a list :

type( a )
<class 'str'>

b = list( a )
# is all you need :)

Abebooks : Survive Like a Spy. How Do They Beat Amazon????

https://www.abebooks.com/servlet/SearchResults?sts=t&cm_sp=SearchF-_-home-_-Results&an=&tn=survive+spy&kn=&isbn=

Python Sorting Two Lists Together

I don't get it either, but it works..

https://codereview.stackexchange.com/questions/138702/sorting-two-lists

s = sorted( zip( a, b) )    # a is master, b is slave
a,b = map( list, zip(*s) )
# and that's it! The genius of Guido Van Rossum

Highlight Selected Cell or Row in Excel - Aus Tom Urtis

It's literally this easy, if you know how.

To highlight the selected cell (automatically that is.. not doing something each time you select something :) :

Get to the Visual Basic editor (might have to enable the Developer tab and then hit View Code -- google this for the way, it's not here)
Then, paste (thanks TU) :

Private Sub Worksheet_SelectionChange(ByVal Target As Range) Application.ScreenUpdating = False ' Clear the color of all the cells Cells.Interior.ColorIndex = 0 ' Highlight the active cell Target.Interior.ColorIndex = 8 Application.ScreenUpdating = True End Sub

That's it. You just paste this and File > Close and Return to Excel and MAGIC happens! Sufficiently advanced technology!!

And for highlighting the entire row AND column (tweak the code as necessary if you want only..) :

Private Sub Worksheet_SelectionChange(ByVal Target As Range) If Target.Cells.Count > 1 Then Exit Sub Application.ScreenUpdating = False ' Clear the color of all the cells Cells.Interior.ColorIndex = 0 With Target ' Highlight the entire row and column that contain the active cell .EntireRow.Interior.ColorIndex = 8 .EntireColumn.Interior.ColorIndex = 8 End With Application.ScreenUpdating = True End Sub

And how do you know what number to use for the ColorIndex?

http://dmcritchie.mvps.org/excel/colors.htm

If you want his book :