#!/usr/bin/env python
# coding: utf-8

# # Biệt lệ (exception) và xác nhận (assertion)
# 
# ## Biệt lệ

# In[2]:


try:
    a = int(input('Tell me one number:'))
    b = int(input('Tell me another number:'))
    print(a/b)
    print('Okay')
except:
    print('Bug in user input.')
print('Outside')


# In[ ]:


try:
    a = int(input('Tell me one number:'))
    b = int(input('Tell me another number:'))
    print('a/b =', a/b)
    print('a+b =', a+b)
except ValueError:
    print('Could not convert to a number.')
except ZeroDivisionError:
    print('Can\'t divide by zero')
except:
    print('Something went very wrong.')
print('Outside')


# ## Ví dụ

# In[ ]:


while True:
    try:
        n = input('Please enter an integer:')
        n = int(n)
        break
    except ValueError:
        print('Input not an integer; try again')
print('Correct input of an integer')


# In[3]:


data = []

file_name = input("Provide a name of a file of data ")

try:
    fh = open(file_name, 'r')
except IOError:
    print('cannot open', file_name)
else:
    for new in fh:
        if new != '\n':
            addIt = new[:-1].split(',') #remove trailing \n
            data.append(addIt)
finally:
    fh.close() # close file even if fail
    
# open file Files/testGradesData.py


# In[4]:


data


# In[5]:


data = []

file_name = input("Provide a name of a file of data ")

try:
    fh = open(file_name, 'r')
except IOError:
    print('cannot open', file_name)
else:
    for new in fh:
        if new != '\n':
            addIt = new[:-1].split(',') #remove trailing \n
            data.append(addIt)
finally:
    fh.close() # close file even if fail

gradesData = []
if data:
    for student in data:
        try:
            gradesData.append([student[0:2], [student[2]]])
        except IndexError:
            gradesData.append([student[0:2], []])


# In[6]:


gradesData


# In[7]:


data = []

file_name = input("Provide a name of a file of data ")

try:
    fh = open(file_name, 'r')
except IOError:
    print('cannot open', file_name)
else:
    for new in fh:
        if new != '\n':
            addIt = new[:-1].split(',') #remove trailing \n
            data.append(addIt)
finally:
    fh.close() # close file even if fail

gradesData = []
if data:
    for student in data:
        try:
            name = student[0:-1]
            grades = int(student[-1])
            gradesData.append([name, [grades]])
        except ValueError:
            gradesData.append([student[:], []])


# In[8]:


gradesData


# ## Phát sinh biệt lệ

# In[9]:


def get_ratios(L1, L2):
    """ Assumes: L1 and L2 are lists of equal length of numbers
        Returns: a list containing L1[i]/L2[i] """
    ratios = []
    for index in range(len(L1)):
        try:
            ratios.append(L1[index]/float(L2[index]))
        except ZeroDivisionError:
            ratios.append(float('NaN')) #NaN = Not a Number
        except:
            raise ValueError('get_ratios called with bad arg')
    return ratios


# In[11]:


L1 = [1, 2, 3, 4]
L2 = [5, 6, 7, 8]
get_ratios(L1, L2)


# In[12]:


L3 = [5, 6, 7]
get_ratios(L1, L3)


# In[14]:


L4 = [5, 6, 7, 0]
get_ratios(L1, L4)


# In[20]:


def get_stats(class_list):
    new_stats = []
    for elt in class_list:
        new_stats.append([elt[0], elt[1], avg(elt[1])])
    return new_stats 

#def avg(grades):
#    return sum(grades)/len(grades)

#def avg(grades):
#    try:
#        return sum(grades)/len(grades)
#    except ZeroDivisionError:
#        print('no grades data')

def avg(grades):
    try:
        return sum(grades)/len(grades)
    except ZeroDivisionError:
        print('no grades data')
        return 0.0


# In[21]:


test_grades = [[['peter', 'parker'], [10.0, 5.0, 85.0]], 
           [['bruce', 'wayne'], [10.0, 8.0, 74.0]],
           [['captain', 'america'], [8.0,10.0,96.0]],
           [['deadpool'], []]]
get_stats(test_grades)


# ## Assertion

# In[25]:


def avg(grades):
    assert not len(grades) == 0, 'no grades data'
    return sum(grades) / len(grades)


# In[26]:


avg([])


# - - -
# [Trước: Kiểm thử chương trình](http://nbviewer.jupyter.org/github/manleviet/introCSusingPython/blob/master/7%20-%20Ki%E1%BB%83m%20th%E1%BB%AD%20ch%C6%B0%C6%A1ng%20tr%C3%ACnh.ipynb) | 
# [Mục lục](http://nbviewer.jupyter.org/github/manleviet/introCSusingPython/blob/master/index.ipynb) | 
# [Tiếp: Lập trình Hướng đối tượng](http://nbviewer.jupyter.org/github/manleviet/introCSusingPython/blob/master/9%20-%20L%E1%BA%ADp%20tr%C3%ACnh%20H%C6%B0%E1%BB%9Bng%20%C4%91%E1%BB%91i%20t%C6%B0%E1%BB%A3ng.ipynb)