編寫分段函數(shù)子函數(shù)

PYTHON編程 (PYTHON PROGRAMMING)

In Python, you can define your own functions.

在Python中，您可以定義自己的函數(shù)。

先決條件 (Prerequisites)

If you do not familiar with Python, the article below will give you a little bit of introduction to Python.

如果您不熟悉Python，則下面的文章將為您提供一些Python簡介。

You will have the moment to follow these newfound skills in data science contexts.

您將有時(shí)間在數(shù)據(jù)科學(xué)環(huán)境中關(guān)注這些新發(fā)現(xiàn)的技能。

define functions without parameters

定義不帶參數(shù)的功能

define functions with a single parameter

用單個(gè)參數(shù)定義函數(shù)

define functions that return a single value and multiple values

定義返回單個(gè)值和多個(gè)值的函數(shù)

To define a function, we begin with the keyword def followed by the function name, and a set of parentheses and a colon. This section of code is called a function header. To complete the function definition, you can write the function body and print the output.

為了定義一個(gè)函數(shù)，我們以關(guān)鍵字def開頭，后跟函數(shù)名稱，以及一組括號(hào)和一個(gè)冒號(hào)。 這部分代碼稱為函數(shù)標(biāo)頭 。 要完成功能定義，您可以編寫功能主體并打印輸出。

Author作者

The code inside the function body is executed if the function is called. When you call a function as you do with prebuild functions, this should return the value. What if you want to attach a parameter inside the function?

如果調(diào)用函數(shù)，則將執(zhí)行函數(shù)體內(nèi)的代碼。 當(dāng)您像使用預(yù)構(gòu)建函數(shù)一樣調(diào)用函數(shù)時(shí)，這應(yīng)該返回值。 如果要在函數(shù)內(nèi)附加參數(shù)怎么辦？

Author作者

To add that functionality, you can add a parameter to the function definition in between the parenthesis. You see that we add a parameter num to the new function body as a variable. The function now accepts a single parameter and prints out its value. What if we do not want to print that value directly? Is it possible to return the value and assign it to a variable?

要添加該功能，可以在括號(hào)之間的功能定義中添加參數(shù)。 您會(huì)看到我們將參數(shù)num作為變量添加到了新函數(shù)體中。 該函數(shù)現(xiàn)在接受單個(gè)參數(shù)并輸出其值。 如果我們不想直接打印該值怎么辦？ 是否可以返回值并將其分配給變量 ？

Author作者

Your function can return the new value by adding the return keyword, followed by the value to return. We can assign to a variable when the result of the function called. Another essential aspect of writing functions in Python is docstrings. It is used to describe your function.

您的函數(shù)可以通過添加return關(guān)鍵字，后跟要返回的值來返回新值。 當(dāng)函數(shù)的結(jié)果被調(diào)用時(shí)，我們可以分配一個(gè)變量 。 用Python編寫函數(shù)的另一個(gè)重要方面是docstrings 。 它用來描述您的功能。

Author作者

These descriptions are your function documentation. Anyone who reads your functions will understand the function without having to trace through all the code. Function docstrings are placed in the next line after the function header and placed between triple quotation marks.

這些描述是您的功能文檔。 讀取您的函數(shù)的任何人都將理解該函數(shù)，而不必遍歷所有代碼。 函數(shù)文檔字符串放在函數(shù)標(biāo)題之后的下一行中，并放在三引號(hào)之間。

What if you want to pass multiple arguments to your functions and return not just one value, but various values from them?

如果您想將多個(gè)參數(shù)傳遞給函數(shù)并不僅返回一個(gè)值，還返回多個(gè)值，該怎么辦？

You can achieve this by having your function to accept two parameters instead of just one. You may also consider changing your function name and docstrings to reflect this new behavior. You can call the function by giving two arguments because it has two parameters, as stated in the function header.

您可以通過讓函數(shù)接受兩個(gè)參數(shù)而不是一個(gè)參數(shù)來實(shí)現(xiàn)此目的。 您也可以考慮更改函數(shù)名稱和文檔字符串以反映此新行為。 您可以通過提供兩個(gè)參數(shù)來調(diào)用該函數(shù)，因?yàn)樗哂袃蓚€(gè)參數(shù)，如函數(shù)頭中所述。

Author作者

The order in which the arguments are stated has to matches the order of the function header’s parameters. You can also specify your function to return multiple values. You can make this by creating objects which are known as tuples in your functions.

聲明參數(shù)的順序必須與函數(shù)頭參數(shù)的順序匹配。 您還可以指定函數(shù)以返回多個(gè)值。 您可以通過在函數(shù)中創(chuàng)建稱為元組的對(duì)象來實(shí)現(xiàn)此目的。

A tuple may contain multiple values like a list. However, there are some differences:

元組可以包含多個(gè)值，例如列表。 但是，有一些區(qū)別：

• Unlike a list, a tuple is immutable, and you cannot modify the values in a tuple once it has been created
  與列表不同，元組是不可變的，創(chuàng)建元組后就無法對(duì)其進(jìn)行修改
• While lists are declared using square brackets [], tuples are constructed using a set of parentheses ()
  雖然列表使用方括號(hào)[]聲明，但元組是使用一組括號(hào)()構(gòu)造的

Author作者

You can unpack a tuple into numerous variables in one line, and assign it to the variables. Additionally, you can also access specific tuple elements as you do with lists. You can use zero-indexing to access the elements.

您可以在一行中將一個(gè)元組拆成多個(gè)變量 ，然后將其分配給這些變量 。 此外，您也可以像使用列表一樣訪問特定的元組元素。 您可以使用零索引來訪問元素。

Are you ready to define your own functions?

您準(zhǔn)備好定義自己的功能了嗎？

Other Interesting Articles#1 Function Arguments: Default, Keyword, and Arbitrary#2 Scope of Variable and LEGB Rule#3 Python: Procedural or Object-Oriented Programming?#4 Data Science with Python: How to Use NumPy Library#5 Do you have the Software Engineer and Data Scientist skills?

關(guān)于作者 (About the Author)

Wie Kiang is a researcher who is responsible for collecting, organizing, and analyzing opinions and data to solve problems, explore issues, and predict trends.

Wie Kiang是一位研究人員，負(fù)責(zé)收集，組織和分析意見和數(shù)據(jù)以解決問題，探索問題和預(yù)測(cè)趨勢(shì)。

He is working in almost every sector of Machine Learning and Deep Learning. He is carrying out experiments and investigations in a range of areas, including Convolutional Neural Networks, Natural Language Processing, and Recurrent Neural Networks.

他幾乎在機(jī)器學(xué)習(xí)和深度學(xué)習(xí)的每個(gè)領(lǐng)域工作。 他正在許多領(lǐng)域進(jìn)行實(shí)驗(yàn)和研究，包括卷積神經(jīng)網(wǎng)絡(luò)，自然語言處理和遞歸神經(jīng)網(wǎng)絡(luò)。

Connect on LinkedIn

在 LinkedIn上 連接

翻譯自: https://towardsdatascience.com/writing-your-own-functions-40d381bd679

編寫分段函數(shù)子函數(shù)

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