1. Scientific Programming in Python -- Cheat Sheet
2018/1/26
2018/1/26
Operations and variables
a = → 2**10 a/b : division
a += 1 a *= 2 a // b : floor division
(e.g. 10 // 3 is 3)
Strings
Built-in functions
a = “this”
b = “string”
a + b → “this string”
“A” * 3 → “AAA”
a[0] → “t”
a[1] → “h”
a[0:2] → “th”
a[-1] → “s”
dir(x) : names, functions, variables
available in x
type(x) : type of x
int(x) : convert into integer
float(x) : convert into float
str(x) : convert into string
list(x) : convert into a list
tuple(x) : convert into tuple
print(x) : print the content of x
bool(x) : convert into boolean
del x : delete x from scope
Boolean type
Print
True, False
∅, {}, [], (), None, “” are all False.
All other variables or values are True
print(“{0} isn’t equal to {1}”.format(1, 2))
print(“{0:f}”.format(1.2345)
➥conversion to float
Other
Module
sequence = “this is amazing”
sequence.split()
“this” in sequence → True
“that” in sequence → False
import math
from math import pi
import math as mymath
from math import pi as PI
Files

2. list (mutable, ordered)
2018/1/26
tuple (immutable)
list (mutable, ordered)
t1 = (1, 2, 3)
t2 = 1, 2, 3
t3 = tuple(“aa”)
t3 = tuple([1, 2, 3])
t1.count(1)
l1 = [1, 2, 3]
l2 = list(t1)
l1[2] = 10
l4 = [1] * 5 → [1, 1, 1, 1, 1]
l1 + l1 → [1, 2, 3, 1, 2, 3]
l1.append([4, 5]) → [1, 2, 3, [4, 5]]
l1.extend([4, 5]) → [1, 2, 3, 4, 5]
⚠️ extend is an inplace operator
dictionary (mutable)
set (mutable, unique unordered)
d1 = {}
d2 = {“a”:1, “b”:2}
d3[“a”] → 1
d2.items()
d2.keys()
d2.values()
s1 = {“a”, “b”, “c”, “c”} → {“a”, “b”, “c”}
Types of collections
Function
def myfunc(x, y, *args, **kargs):
x + y
args[0]
kargs.keys()
return x + y + args[0] + 1
Conditional structures
if a == 1:
# do something
pass
elif a == 2:
else:
For loop
for i in range(10):
print(i)
List comprehensions
[x for x in range(10) if x%2==0]