第十三號艦隊
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Useful Tips for Python Programming

Posted on Edited on In

最近實在是太頹廢了，強迫自己寫些新東西
蟒蛇有些新玩具，可以加入自己的工具組合之中

PySnooper

Github Project主業
首先先安裝pysnooper這個package

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$ pip install pysnooper

然後來個最簡單的示範，寫個比官方範例更複雜一點

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@pysnooper.snoop()
def findPrimes(number):
    num = 2
    primes = []
    while num <= number:
        div = 2
        flag = True
        while div * div <= num and flag:
            if num % div == 0:
                flag = False
            div = div + 1
        if flag:
            primes.insert(len(primes), num)
        num = num + 1
    return primes
print(findPrimes(10))

然後可以列出所有中間產物的過程

輸出到Log file

可以指定到不同的Log file

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import pysnooper

@pysnooper.snoop("./debug1.log")
def isPrime(num):
    div = 2
    while div * div <= num:
        if num % div == 0:
            return False
        div = div + 1
    return True

@pysnooper.snoop("./debug.log")
def findPrimes(number):
    num = 2
    primes = []
    while num <= number:
        if isPrime(num):
            primes.insert(len(primes), num)
        num = num + 1
    return primes
print(findPrimes(10))

用不同的Prefix區分

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import pysnooper

@pysnooper.snoop("./debug.log", prefix="--isPrime--")
def isPrime(num):
    div = 2
    while div * div <= num:
        if num % div == 0:
            return False
        div = div + 1
    return True

@pysnooper.snoop("./debug.log", prefix="--findPrimes--")
def findPrimes(number):
    num = 2
    primes = []
    while num <= number:
        if isPrime(num):
            primes.insert(len(primes), num)
        num = num + 1
    return primes
print(findPrimes(10))

stackprinter

Github Project主業
要做的還是先裝上去

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$ pip install stackprinter

接著我們修改上面的範例，讓它Crash

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def isPrime(num):
    div = 0
    while div * div <= num:
        if num % div == 0:
            return False
        div = div + 1
    return True

def findPrimes(number):
    num = 2
    primes = []
    while num <= number:
        if isPrime(num):
            primes.insert(len(primes), num)
        num = num + 1
    return primes
print(findPrimes(10))

執行之後產生以下的 Crash info

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Traceback (most recent call last):
  File "a.py", line 20, in <module>
    print(findPrimes(10))
  File "a.py", line 16, in findPrimes
    if isPrime(num):
  File "a.py", line 7, in isPrime
    if num % div == 0:
ZeroDivisionError: integer division or modulo by zero

如果我們加上了stachpointer

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import stackprinter
stackprinter.set_excepthook(style='darkbg2')

def isPrime(num):
    div = 0
    while div * div <= num:
        if num % div == 0:
            return False
        div = div + 1
    return True

def findPrimes(number):
    num = 2
    primes = []
    while num <= number:
        if isPrime(num):
            primes.insert(len(primes), num)
        num = num + 1
    return primes
print(findPrimes(10))

會變成這樣子

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File a.py, line 20, in <module>
    16           if isPrime(num):
    17               primes.insert(len(primes), num)
    18           num = num + 1
    19       return primes
--> 20   print(findPrimes(10))

File a.py, line 16, in findPrimes
    12   def findPrimes(number):
    13       num = 2
    14       primes = []
    15       while num <= number:
--> 16           if isPrime(num):
    17               primes.insert(len(primes), num)
    ..................................................
     number = 10
     num = 2
     primes = []
    ..................................................

File a.py, line 7, in isPrime
    4    def isPrime(num):
    5        div = 0
    6        while div * div <= num:
--> 7            if num % div == 0:
    8                return False
    ..................................................
     num = 2
     div = 0
    ..................................................

ZeroDivisionError: integer division or modulo by zero

有顏色和箭頭比較容易分析哪裡出錯