X = [1, 2, 3)

y = 4x + 3

a = 4
something ==== is wrong

print(a)

print(Q)

x = 1 + 'abc'

X = 1 / 0

import numpy as np
np.add(1, 2, 3, 4)

x = [1, 2, 3]
print(x[100])

spam = "my all-time favorite"
eggs = 1 / 0

print(spam)

from math import sqrt

def approx_pi(nterms=100):
    k = np.arange(nterms)
    return sqrt(12) * np.sum(-3.0 ** -k / (2 * k + 1))

approx_pi(100)

approx_pi(1000)

try:
    print("this block gets executed first")
except:
    print("this block gets executed if there's an error")

try:
    print("this block gets executed first")
    x = 1 / 0  # ZeroDivisionError
    print("we never get here")
except:
    print("this block gets executed if there's an error")

def safe_divide(a, b):
    try:
        return a / b
    except:
        print("oops, dividing by zero. Returning None.")
        return None
    
print(safe_divide(15, 3))
print(safe_divide(1, 0))

safe_divide(15, 'three')

def better_safe_divide(a, b):
    try:
        return a / b
    except ZeroDivisionError:
        print("oops, dividing by zero. Returning None.")
        return None
    
better_safe_divide(15, 0)

better_safe_divide(15, 'three')

def even_better_safe_divide(a, b):
    try:
        return a / b
    except ZeroDivisionError:
        print("oops, dividing by zero. Returning None.")
        return None
    except TypeError:
        print("incompatible types.  Returning None")
        return None
    

even_better_safe_divide(15, 3)

even_better_safe_divide(15, 0)

even_better_safe_divide(15, 'three')

import os  # the "os" module has useful operating system stuff

def read_file(filename):
    if not os.path.exists(filename):
        raise ValueError("'{0}' does not exist".format(filename))
    f = open(filename)
    result = f.read()
    f.close()
    return result

%%file tmp.txt
this is the contents of the file

read_file('tmp.txt')

read_file('file.which.does.not.exist')

class NonExistentFile(RuntimeError):
    # you can customize exception behavior by defining class methods.
    # we won't discuss that here.
    pass


def read_file(filename):
    if not os.path.exists(filename):
        raise NonExistentFile(filename)
    f = open(filename)
    result = f.read()
    f.close()
    return result

read_file('tmp.txt')

read_file('file.which.does.not.exist')

try:
    print("doing something")
except:
    print("this only happens if it fails")
else:
    print("this only happens if it succeeds")

try:
    print("doing something")
    raise ValueError()
except:
    print("this only happens if it fails")
else:
    print("this only happens if it succeeds")

try:
    print("do something")
except:
    print("this only happens if it fails")
else:
    print("this only happens if it succeeds")
finally:
    print("this happens no matter what.")

try:
    print("do something")
    raise ValueError()
except:
    print("this only happens if it fails")
else:
    print("this only happens if it succeeds")
finally:
    print("this happens no matter what.")

try:
    print("do something")
except:
    print("this only happens if it fails")
else:
    print("this only happens if it succeeds")
print("this happens no matter what.")

def divide(x, y):
    try:
       result = x / y
    except ZeroDivisionError:
        print("division by zero!")
        return None
    else:
        print("result is", result)
        return result
    finally:
        print("some sort of cleanup")

divide(15, 3)

divide(15, 0)

def entropy(p):
    p = np.asarray(p)  # convert p to array if necessary
    items = p * np.log(p)
    return -np.sum(items)

p = np.arange(5.)
p /= p.sum()

entropy(p)

def entropy(p):
    p = np.asarray(p)  # convert p to array if necessary
    print(p)
    items = p * np.log(p)
    print(items)
    return -np.sum(items)

entropy(p)

%%file test_script.py
import numpy as np

def entropy(p):
    p = np.asarray(p)  # convert p to array if necessary
    items = p * np.log(p)
    import IPython; IPython.embed()
    return -np.sum(items)

p = np.arange(5.)
p /= p.sum()
entropy(p)

def entropy(p):
    import pdb; pdb.set_trace()
    p = np.asarray(p)  # convert p to array if necessary
    items = p * np.log(p)
    return -np.sum(items)

entropy(p)

%%file numbers.dat
123 456 789

def add_lines(filename):
    f = open(filename)
    lines = f.read().split()
    f.close()
    result = 0
    for line in lines:
        result += line
    return result

filename = 'numbers.dat'
total = add_lines(filename)
print(total)

%debug