Files! You gotta love them!¶

In [10]:

myfile = open('foo.txt')
data = myfile.read()
myfile.close()

In [11]:

data

Out[11]:

'Hello there!'

In [12]:

myfile = open('foo.txt','w')
myfile.write("Hello there!")
myfile.close()

---------------------------------------------------------------------------
UnsupportedOperation                      Traceback (most recent call last)
Input In [12], in <cell line: 2>()
      1 myfile = open('foo.txt')
----> 2 myfile.write("Hello there!")
      3 myfile.close()

UnsupportedOperation: not writable

In [19]:

myfile = None
def step1():
    global line
    myfile = open("foo.txt","w")
    myfile.write("222 This is line")
    myfile.write("555 This is another line")
def step2():
    myfile = open("foo.txt")
    print("I read",myfile.read())

In [20]:

step1()
step2()

I read 222 This is line555 This is another line

In [21]:

primes = [2,3,5,7,9]

In [22]:

primes[0:3]

Out[22]:

[2, 3, 5]

In [23]:

primes[3:6]

Out[23]:

[7, 9]

In [24]:

primes[0:3] + primes[3:6]

Out[24]:

[2, 3, 5, 7, 9]

In [25]:

# primes[a:b] + primes[b:c] == primes[a:c]

In [26]:

primes.remove(9)

In [27]:

primes

Out[27]:

[2, 3, 5, 7]

In [28]:

p2 = list(primes)

In [29]:

p2.append(11)

In [30]:

primes

Out[30]:

[2, 3, 5, 7]

In [31]:

p2

Out[31]:

[2, 3, 5, 7, 11]

In [32]:

for row in open('foo.txt').read():
    print(row)

H
e
l
l
o
 
t
h
e
r
e
!


T
h
i
s
 
i
s
 
a
 
f
i
l
e
.


I
 
w
a
n
t
 
a
 
b
u
n
c
h
 
o
f
 
l
i
n
e
s
 
i
n
 
i
t
.


T
h
i
s
 
w
a
y
 
I
 
c
a
n
 
d
o
 
a
n
 
e
x
a
m
p
l
e
.

In [33]:

for row in open('foo.txt').read().split("\n"):
    print(row)

Hello there!
This is a file.
I want a bunch of lines in it.
This way I can do an example.

In [34]:

open('foo.txt').read().split("\n")

Out[34]:

['Hello there!',
 'This is a file.',
 'I want a bunch of lines in it.',
 'This way I can do an example.',
 '']

In [35]:

open('foo.txt').readlines()

Out[35]:

['Hello there!\n',
 'This is a file.\n',
 'I want a bunch of lines in it.\n',
 'This way I can do an example.\n']

In [36]:

open('foo.txt').readline()

Out[36]:

'Hello there!\n'

In [37]:

myfile = open('foo.txt')

In [38]:

myfile.readline()

Out[38]:

'Hello there!\n'

In [39]:

myfile.readline()

Out[39]:

'This is a file.\n'

In [40]:

myfile.readline().strip()

Out[40]:

'I want a bunch of lines in it.'

In [52]:

def writeNumbers(name,a,b):
    myfile = open(name,'w')
    myfile.write(str(a)+"\n")
    myfile.write(str(b)+"\n")
    myfile.close()
def averageNumbers(name):
    myfile = open(name)
    a = int(myfile.readline())
    b = int(myfile.readline())
    print("The average is",(a+b)/2)

In [50]:

writeNumbers("test.txt",10,20)

In [53]:

averageNumbers("test.txt")

The average is 15.0

In [ ]: