Getting started with Jupyter and Python¶
The Jupyter notebook¶
Markdown cells¶
Headings are indicated by #, ##, ###, or ####.
- list
- of
- stuff
Some LaTeX
\(\alpha \beta \gamma\)
Creating, deleting and moving cells¶
In [ ]:
here
Getting help¶
In [5]:
range?
Python Basics¶
Basic data types¶
numbers, strings, booleans, None
In [14]:
2
Out[14]:
2
In [15]:
3.14
Out[15]:
3.14
In [16]:
4 + 3j
Out[16]:
(4+3j)
In [17]:
'hello, world'
Out[17]:
'hello, world'
In [19]:
"hello's world"
Out[19]:
"hello's world"
In [20]:
'''This
is a
multi-line
string'''
Out[20]:
'This\nis a \nmulti-line\nstring'
In [ ]:
True, False
In [21]:
None
Operators¶
arithmetic, logical, relational, bitwise, ternary
In [23]:
1 + 2, 1 - 2, 1 * 2,
Out[23]:
(3, -1, 2)
In [24]:
2**3
Out[24]:
8
In [25]:
2/3
Out[25]:
0.6666666666666666
In [26]:
2 // 3
Out[26]:
0
In [28]:
7 % 2 == 0
Out[28]:
False
In [29]:
2 < 3
Out[29]:
True
In [30]:
2 >= 3
Out[30]:
False
In [32]:
2 == 3, 2 != 3
Out[32]:
(False, True)
In [37]:
(1 > 2) or (2 > 1)
Out[37]:
True
In [34]:
(1 > 2) and (2 > 1)
Out[34]:
False
In [35]:
not (1 > 2) and (2 > 1)
Out[35]:
True
In [40]:
7 & 3
Out[40]:
3
Collections¶
list, tuple, set, dict
In [42]:
xs = [1,2,3,4,5]
In [43]:
xs
Out[43]:
[1, 2, 3, 4, 5]
In [44]:
xs[0]
Out[44]:
1
In [53]:
xs[:-1]
Out[53]:
[1, 2, 3, 4]
In [54]:
xs[::-1]
Out[54]:
[5, 4, 3, 2, 1]
In [55]:
xs.append(6)
In [56]:
xs
Out[56]:
[1, 2, 3, 4, 5, 6]
In [57]:
xs.extend([7,8,9])
In [58]:
xs
Out[58]:
[1, 2, 3, 4, 5, 6, 7, 8, 9]
In [59]:
[1,2] + [3,4]
Out[59]:
[1, 2, 3, 4]
In [60]:
[1,2] * 3
Out[60]:
[1, 2, 1, 2, 1, 2]
In [62]:
xs.clear()
In [63]:
xs
Out[63]:
[]
In [65]:
(1,1,2,3,5,8)
Out[65]:
(1, 1, 2, 3, 5, 8)
In [66]:
xs = [1,2,3]
In [67]:
ys = (1,2,3)
In [68]:
xs[1] *= 9
In [69]:
xs
Out[69]:
[1, 18, 3]
In [70]:
ys[1] *= 9
TypeErrorTraceback (most recent call last)
<ipython-input-70-b9a74fac84ed> in <module>()
----> 1 ys[1] *= 9
TypeError: 'tuple' object does not support item assignment
In [71]:
('tom', 'price', 23, '%500,000')
Out[71]:
('tom', 'price', 23, '%500,000')
In [72]:
set([1,1,2,3,4,1,2,3])
Out[72]:
{1, 2, 3, 4}
In [73]:
from collections import Counter
In [74]:
c = Counter([1,1,2,3,4,1,2,3])
In [75]:
c
Out[75]:
Counter({1: 3, 2: 2, 3: 2, 4: 1})
In [77]:
c[3]
Out[77]:
2
In [78]:
d = {'a': 1, 'b': 2}
In [79]:
d
Out[79]:
{'a': 1, 'b': 2}
In [80]:
d['a']
Out[80]:
1
In [81]:
dict(a = 2, b=3)
Out[81]:
{'a': 2, 'b': 3}
Indexing and slicing¶
zero-indexing, start, stop, stride
In [3]:
xs = list(range(10))
In [4]:
xs
Out[4]:
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
In [5]:
xs[0]
Out[5]:
0
In [6]:
xs[2:5]
Out[6]:
[2, 3, 4]
In [7]:
xs[2:9:2]
Out[7]:
[2, 4, 6, 8]
In [8]:
xs[:3]
Out[8]:
[0, 1, 2]
In [9]:
xs[3:]
Out[9]:
[3, 4, 5, 6, 7, 8, 9]
In [10]:
xs[-1]
Out[10]:
9
In [11]:
xs[-3:]
Out[11]:
[7, 8, 9]
In [12]:
xs[::-1]
Out[12]:
[9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
In [13]:
list(reversed(xs))
Out[13]:
[9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
Looping¶
for, while
In [14]:
for i in range(5):
print(i, i**2)
0 0
1 1
2 4
3 9
4 16
In [15]:
for i in [2,5,9]:
print(i)
2
5
9
In [16]:
for i, x in enumerate([2,5,9]):
print(i, x)
0 2
1 5
2 9
In [17]:
for i, x in enumerate([2,5,9], start=1):
print(i, x)
1 2
2 5
3 9
In [18]:
i = 0
while i < 5:
i += 1
print(i)
1
2
3
4
5
In [19]:
i = 0
while True:
i += 1
print(i)
if i > 5:
break
1
2
3
4
5
6
In [20]:
i = 0
while 'not very true':
i += 1
print(i)
if i > 5:
break
1
2
3
4
5
6
Cotnrol flow¶
if-elif-else, continue, break, pass
In [23]:
for i in range(1, 101):
if i > 50:
break
if i % 3 == 0:
continue
if (i % 3 == 0) & (i % 5 == 0):
print("FizzBuzz", end=',')
elif (i % 3 == 0):
print("Fizz", end=',')
elif (i % 5 == 0):
print("Buzz", end=',')
else:
print(i, end=',')
1,2,4,Buzz,7,8,Buzz,11,13,14,16,17,19,Buzz,22,23,Buzz,26,28,29,31,32,34,Buzz,37,38,Buzz,41,43,44,46,47,49,Buzz,
List, set, dictionary comprehensions¶
comprehensions, if, nested comprehensions
In [25]:
xs = []
for i in range(10):
if i % 2 == 0:
xs.append(i**2)
xs
Out[25]:
[0, 4, 16, 36, 64]
In [26]:
[i**2 for i in range(10) if i % 2 == 0]
Out[26]:
[0, 4, 16, 36, 64]
In [36]:
xs = []
for i in range(3):
for j in range(4):
xs.append((i,j))
if j == 1:
break
print(xs)
[(0, 0), (0, 1), (1, 0), (1, 1), (2, 0), (2, 1)]
In [29]:
print([(i,j) for i in range(3) for j in range(4)])
[(0, 0), (0, 1), (0, 2), (0, 3), (1, 0), (1, 1), (1, 2), (1, 3), (2, 0), (2, 1), (2, 2), (2, 3)]
In [ ]:
[i**2 for i in range(10**400)]
In [33]:
gen = (i**2 for i in range(10**400))
In [34]:
for i in gen:
print(i)
if i > 1000:
break
0
1
4
9
16
25
36
49
64
81
100
121
144
169
196
225
256
289
324
361
400
441
484
529
576
625
676
729
784
841
900
961
1024
Generator expressions¶
laziness, iterators, iter, next, StopIteration
In [37]:
(i for i in range(10) if i % 3 == 0)
Out[37]:
<generator object <genexpr> at 0x7f5876b890f8>
In [38]:
{i for i in [1,1,2,3,4,3]}
Out[38]:
{1, 2, 3, 4}
In [39]:
{s: len(s) for s in ['apple', 'pear', 'bababa']}
Out[39]:
{'apple': 5, 'bababa': 6, 'pear': 4}
Built-in functions¶
sum, range, enumerate, sorted, reversed
In [40]:
sum(range(10))
Out[40]:
45
In [42]:
sorted([3,1,5,2,4])
Out[42]:
[1, 2, 3, 4, 5]
In [43]:
reversed([3,1,5,2,4])
Out[43]:
<list_reverseiterator at 0x7f5876baf710>
In [46]:
sum(range(5), 10)
Out[46]:
20
Standard libraries¶
string, math, random
In [47]:
import string
In [48]:
string.ascii_lowercase
Out[48]:
'abcdefghijklmnopqrstuvwxyz'
In [49]:
string.ascii_uppercase
Out[49]:
'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
In [50]:
string.punctuation
Out[50]:
'!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~'
In [51]:
from string import punctuation, ascii_letters
In [52]:
punctuation
Out[52]:
'!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~'
In [53]:
ascii_letters
Out[53]:
'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
In [54]:
import string as ss
In [55]:
ss.digits
Out[55]:
'0123456789'
In [56]:
import math
In [57]:
math.sqrt(2)
Out[57]:
1.4142135623730951
In [58]:
import random
In [59]:
random.uniform(0, 5)
Out[59]:
4.254708589608265
I/O¶
reading and writing text files, context managers
In [61]:
%%file mary.txt
mary had a little lamb
little lamb
little lamb
its fleece was white as snow
Writing mary.txt
In [65]:
with open('mary.txt') as f:
for line in f:
if not line.startswith('#'):
print(line.strip())
mary had a little lamb
little lamb
little lamb
its fleece was white as snow
In [66]:
with open('mary.txt') as f:
text = f.read()
In [67]:
text
Out[67]:
'\nmary had a little lamb\nlittle lamb\nlittle lamb\nits fleece was white as snow'
In [68]:
with open('mary.txt') as f:
text = f.readlines()
In [69]:
text
Out[69]:
['\n',
'mary had a little lamb\n',
'little lamb\n',
'little lamb\n',
'its fleece was white as snow']
Polyglot programming¶
Using bash and R together with Python
In [70]:
%load_ext rpy2.ipython
In [71]:
x = %R 1:3
In [72]:
x
Out[72]:
array([1, 2, 3], dtype=int32)
In [75]:
%%R -o iris
head(iris)
Sepal.Length Sepal.Width Petal.Length Petal.Width Species
1 5.1 3.5 1.4 0.2 setosa
2 4.9 3.0 1.4 0.2 setosa
3 4.7 3.2 1.3 0.2 setosa
4 4.6 3.1 1.5 0.2 setosa
5 5.0 3.6 1.4 0.2 setosa
6 5.4 3.9 1.7 0.4 setosa
In [76]:
iris
Out[76]:
| Sepal.Length | Sepal.Width | Petal.Length | Petal.Width | Species | |
|---|---|---|---|---|---|
| 1 | 5.1 | 3.5 | 1.4 | 0.2 | setosa |
| 2 | 4.9 | 3.0 | 1.4 | 0.2 | setosa |
| 3 | 4.7 | 3.2 | 1.3 | 0.2 | setosa |
| 4 | 4.6 | 3.1 | 1.5 | 0.2 | setosa |
| 5 | 5.0 | 3.6 | 1.4 | 0.2 | setosa |
| 6 | 5.4 | 3.9 | 1.7 | 0.4 | setosa |
| 7 | 4.6 | 3.4 | 1.4 | 0.3 | setosa |
| 8 | 5.0 | 3.4 | 1.5 | 0.2 | setosa |
| 9 | 4.4 | 2.9 | 1.4 | 0.2 | setosa |
| 10 | 4.9 | 3.1 | 1.5 | 0.1 | setosa |
| 11 | 5.4 | 3.7 | 1.5 | 0.2 | setosa |
| 12 | 4.8 | 3.4 | 1.6 | 0.2 | setosa |
| 13 | 4.8 | 3.0 | 1.4 | 0.1 | setosa |
| 14 | 4.3 | 3.0 | 1.1 | 0.1 | setosa |
| 15 | 5.8 | 4.0 | 1.2 | 0.2 | setosa |
| 16 | 5.7 | 4.4 | 1.5 | 0.4 | setosa |
| 17 | 5.4 | 3.9 | 1.3 | 0.4 | setosa |
| 18 | 5.1 | 3.5 | 1.4 | 0.3 | setosa |
| 19 | 5.7 | 3.8 | 1.7 | 0.3 | setosa |
| 20 | 5.1 | 3.8 | 1.5 | 0.3 | setosa |
| 21 | 5.4 | 3.4 | 1.7 | 0.2 | setosa |
| 22 | 5.1 | 3.7 | 1.5 | 0.4 | setosa |
| 23 | 4.6 | 3.6 | 1.0 | 0.2 | setosa |
| 24 | 5.1 | 3.3 | 1.7 | 0.5 | setosa |
| 25 | 4.8 | 3.4 | 1.9 | 0.2 | setosa |
| 26 | 5.0 | 3.0 | 1.6 | 0.2 | setosa |
| 27 | 5.0 | 3.4 | 1.6 | 0.4 | setosa |
| 28 | 5.2 | 3.5 | 1.5 | 0.2 | setosa |
| 29 | 5.2 | 3.4 | 1.4 | 0.2 | setosa |
| 30 | 4.7 | 3.2 | 1.6 | 0.2 | setosa |
| ... | ... | ... | ... | ... | ... |
| 121 | 6.9 | 3.2 | 5.7 | 2.3 | virginica |
| 122 | 5.6 | 2.8 | 4.9 | 2.0 | virginica |
| 123 | 7.7 | 2.8 | 6.7 | 2.0 | virginica |
| 124 | 6.3 | 2.7 | 4.9 | 1.8 | virginica |
| 125 | 6.7 | 3.3 | 5.7 | 2.1 | virginica |
| 126 | 7.2 | 3.2 | 6.0 | 1.8 | virginica |
| 127 | 6.2 | 2.8 | 4.8 | 1.8 | virginica |
| 128 | 6.1 | 3.0 | 4.9 | 1.8 | virginica |
| 129 | 6.4 | 2.8 | 5.6 | 2.1 | virginica |
| 130 | 7.2 | 3.0 | 5.8 | 1.6 | virginica |
| 131 | 7.4 | 2.8 | 6.1 | 1.9 | virginica |
| 132 | 7.9 | 3.8 | 6.4 | 2.0 | virginica |
| 133 | 6.4 | 2.8 | 5.6 | 2.2 | virginica |
| 134 | 6.3 | 2.8 | 5.1 | 1.5 | virginica |
| 135 | 6.1 | 2.6 | 5.6 | 1.4 | virginica |
| 136 | 7.7 | 3.0 | 6.1 | 2.3 | virginica |
| 137 | 6.3 | 3.4 | 5.6 | 2.4 | virginica |
| 138 | 6.4 | 3.1 | 5.5 | 1.8 | virginica |
| 139 | 6.0 | 3.0 | 4.8 | 1.8 | virginica |
| 140 | 6.9 | 3.1 | 5.4 | 2.1 | virginica |
| 141 | 6.7 | 3.1 | 5.6 | 2.4 | virginica |
| 142 | 6.9 | 3.1 | 5.1 | 2.3 | virginica |
| 143 | 5.8 | 2.7 | 5.1 | 1.9 | virginica |
| 144 | 6.8 | 3.2 | 5.9 | 2.3 | virginica |
| 145 | 6.7 | 3.3 | 5.7 | 2.5 | virginica |
| 146 | 6.7 | 3.0 | 5.2 | 2.3 | virginica |
| 147 | 6.3 | 2.5 | 5.0 | 1.9 | virginica |
| 148 | 6.5 | 3.0 | 5.2 | 2.0 | virginica |
| 149 | 6.2 | 3.4 | 5.4 | 2.3 | virginica |
| 150 | 5.9 | 3.0 | 5.1 | 1.8 | virginica |
150 rows × 5 columns