COMP10001 Lecture 5: Week 5
25 May 2018
School
Department
Course
Professor
from collections import defaultdict
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dict = defaultdict(int)
dict[d] += 1
for i in str(x):
return dict
def function(x):
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defaultdict
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mylist = []
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mylist.append(val, key)
for key, val in mydict.items():
[val, key for key, val in mydict.items()]
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list comprehension turns a for loop into one line
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Tips and tricks:
a bug = an error/flaw in a piece of code that leads to a malfunction
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syntax errors = incompatibility with the syntax of the programming language
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run
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time errors = errors at run
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time, causing the code to crash
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logic errors = design error, such that the code runs but doesn't do what it is supposed to
do
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bug types
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debugging = the process of systematically finding and fixing bugs
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equality vs assignment
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printing vs returning from functions
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correct use of types
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incorrect use of function/method
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spelling and capitalisation
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loops and incrementing
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conditionals and indentation
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namespace problems
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things to watch out for
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Bugs and debugging:
modules = pre
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pared stores of convenient methods/variables which expand the functionality
of Python
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import = adds the module to the local namespace
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from x import * = imports all methods and constants from a library into the local namespace
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from x import a, b = selectively import objects
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from x import a as b = import a but rename it as b
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Modules:
to read data from a local file:
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FILENAME = "qwerty.txt"
text = open(FILENAME).read()
lines = open(FILENAME).readlines()
f = open(FILENAME)
.read() = reads the entire file
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.readlines() = reads into a list of lines
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for line in file = iterates over lines in the file
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to write to a file:
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FILENAME = "qwerty.txt"
Files:
Week 5
Wednesday, 4 April 2018 6:51 PM
Foundations of Computing Page 1
