30 Essential Python Interview Questions You Should Know.

###Q-16: How Does The Ternary Operator Work In Python?

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x, y = 35, 75
smaller = x if x < y else y
print(smaller)

###Q-17: What Does The Keyword Do?
self就是self呀

###Q-18: What Are Different Methods To Copy An Object In Python?
基础的l2=l1[:]
copy.copy()

• 外层copy,内层会随着原对象改变，抄了作业还要跟着改
  copy.deepcopy()
• 内层copy，抄完作业就不改了

###Q-19: What Is The Purpose Of Doc Strings In Python?
给你一个BB机会

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class A(object):
    """我就在这里BB"""


a = A()
print(a.__doc__)

###Q-20: Which Python Function Will You Use To Convert A Number To A String?
str()

###Q-21: How Do You Debug A Program In Python? Is It Possible To Step Through Python Code?

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import pdb
pdb.set_trace()

###Q-22: List Down Some Of The PDB Commands For Debugging Python Programs?

• Add breakpoint – b
• Resume execution – c
• Step by step debugging – s
• Move to next line – n
• List source code – l
• Print an expression – p

###Q-23: What Is The Command To Debug A Python Program?

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python -m pdb debug_file.py

###Q-24: How Do You Monitor The Code Flow Of A Program In Python?

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import sys
def trace_calls(frame, event, arg):
    # The 'call' event occurs before a function gets executed.
    if event != 'call':
        return
    # Next, inspect the frame data and print information.
    print('Function name=%s, line num=%s' % (frame.f_code.co_name, frame.f_lineno))
    return

def demo2():
    print('in demo2()')

def demo1():
    print('in demo1()')
    demo2()

sys.settrace(trace_calls)
demo1()

###Q-25: Why And When Do You Use Generators In Python?

###Q-26: What Does The Keyword Do In Python?
协程

###Q-27: How To Convert A List Into Other Data Types?
to String

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weekdays = ['sun','mon','tue','wed','thu','fri','sat']
listAsString = ' '.join(weekdays)
print(listAsString)

to Tuple

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weekdays = ['sun','mon','tue','wed','thu','fri','sat']
listAsTuple = tuple(weekdays)
print(listAsTuple)

to Set

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weekdays = ['sun','mon','tue','wed','thu','fri','sat','sun','tue']
listAsSet = set(weekdays)
print(listAsSet)

to Dictionary

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weekdays = ['sun','mon','tue','wed','thu','fri']
listAsDict = dict(zip(weekdays[0::2], weekdays[1::2]))
print(listAsDict)

###Q-28: How Do You Count The Occurrences Of Each Item Present In The List Without Explicitly Mentioning Them?

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weekdays = ['sun','mon','tue','wed','thu','fri','sun','mon','mon']
print(weekdays.count('mon'))

###Q-29: What Is NumPy And How Is It Better Than A List In Python?
Numpy底层结构不一样，c写的，而且优化的很好

###Q-30: What Are Different Ways To Create An Empty NumPy Array In Python?
看Numpy的文档吧 0.0