python’101 · python’code output docs names’='jon’roberts\ternie’mross'...
TRANSCRIPT
python 101
Docs
ge/ng python
h0p://www.python.org
Docs
IDLE -‐ the python development environment
python code
output
Docs
print()print('Hello World!')print('UlGmate answer: ', 27 + 15)
Hello World!UlGmate answer: 42
Hello World!
<-‐ blank line
python code
output
Docs
string
x = 'abcde'print(x)
abcde
python code
output
Docs
i = 2j = 3print('integer divide 2/3: ', i/j)
integer divide 2/3: 0
integer
python code
output
Docs
i = 2.0 #floatj = 3 # integerprint('floaGng point divide 2.0/3: ', i/j)
floaGng point divide 2.0/3: 0.666666666667
float
python code
output
Docs
x = 'abcde'print(x[0])print(x[-‐1])print(x[1:4])
aebcd
sequence -‐ string
python starts counGng at zero
python code
output
Docs
x = (1,2,3,4,5)print(x[0])print(x[-‐1])print(x[1:4])
15(2, 3, 4)
sequence -‐ tuple
python code
output
Docs
x = [1,2,3,4,5]print(x[0])print(x[-‐1])print(x[1:4])
15[2, 3, 4]
sequence -‐ list
python code
output
Docs
x = (1,2,3,4,5)x[0] = 9
Traceback (most recent call last): File "/Users/jroberts/Desktop/test.py", line 2, in <module> x[0] = 9TypeError: 'tuple' object does not support item assignment
tuple is immutable
python code
output
Docs
x = [1,2,3,4,5]x[0] = 9print(x)
[9, 2, 3, 4, 5]
list is mutable
python code
output
Docs
x = [1,2,3,4,5]x[0] = 'a'x[1] = (4,5,6)print(x)
['a', (4, 5, 6), 3, 4, 5]
lists can have mixed types
python code
output
Docs
answer = 42pi = 3.141592654print('the answer is %i and pi is approx. %f' % (answer,pi))print('the answer is %i and pi is approx. %.2f' % (answer,pi))print('%i\t%.2f\n' % (answer,pi))
the answer is 42 and pi is approx. 3.141593the answer is 42 and pi is approx. 3.1442 3.14
string % forma/ng
tab
line break
python code
output
Docs
print(float(42))print(int(5.75))print(round(5.75))print(int(round(5.75)))print(range(5))
42.056.06[0, 1, 2, 3, 4]
funcGons()
python code
output
Docs
import randomnumbers = [1,2,3,4,5]random.shuffle(numbers)print(numbers)
[2, 5, 4, 1, 3]
funcGons from imported libraries
python code
output
Docs
names = 'Jon Roberts\tErnie Mross'print(1, names.split())print(2, names.split('\t'))print(3, names.split('\t')[0])print(4, names.lower().split('\t')[0].split())
1 ['Jon', 'Roberts', 'Ernie', 'Mross']2 ['Jon Roberts', 'Ernie Mross']3 Jon Roberts4 ['jon', 'roberts']
methods -‐ funcGons “a0ached” to objects
'\t' is the tab character
python code
output
Docs
words = ['one','two','three']if 'three' in words: print('found three')
found three
what if?
python code
output
Docs
x = 5if x >5: print('big x')else: print('x is less than or equal to 5')
x is less than or equal to 5
more if?
python code
output
Docs
x = 1if x == 3:
print('three')elif x == 5:
print('five')else:
print('not found')
not found
even more if?
python code
output
Docs
for num in range(4): x = num+10 print(x)print('done')
10111213done
loops
python code
output
Docs
nameList = ['jon','ernie','linda']for aName in nameList: print('aName -‐> ', aName)
aName -‐> jonaName -‐> ernieaName -‐> linda
more loops
python code
output
Docs
done = False ; x = 0while not done: x += 3 if x>9: done = True print(x)
36912
even more loops
python code
output
Docs
infile = open('tabtext.txt', mode='rU')for aLine in infile: print(aLine.split('\t'))infile.close()
['line 1', 'abc', 'def\n']['line 2', 'ghi', 'jkl']
reading files
python code
output
Docs
infile = open('tabtext.txt', mode='rU')for aLine in infile: print(aLine.strip().split('\t'))infile.close()
['line 1', 'abc', 'def']['line 2', 'ghi', 'jkl']
more reading files
python code
output
Docs
data = [[1,2],[3,4]]ouoile = open('tabtextout.txt', mode='w')for subList in data: ouoile.write('%i\t%i\n' % (subList[0],subList[1]))ouoile.close()
1 23 4
wriGng files
‘w’ for write, ‘a’ for append
you must close the file to be certain all data are wri0en
tabs
line breaks