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Description
Summary
本章小结
- A loop is used to repeat code as many times as needed.
- We use a
for
loop when we know how many iterations the loop will do; we use a while loop when we don’t know how many iterations a loop will do. - Python uses indentation to determine which lines of code go together.
- A dictionary is a mapping from keys (such as words) to values (such as their frequencies).
- We need to open a file before we can read from it.
- Once a file is open, we can use methods or a loop to read its lines.
- Some modules (such as csv and zipfile) come with Python and can be used by importing them.
- Other modules, such as matplotlib, need to be installed first before they can be imported and used.
- 循环用于根据需要重复执行代码多次。
- 当我们明确知道循环将执行的迭代次数时,使用
for
循环;而在不确定循环将执行多少次迭代时,则采用 while 循环。 - Python 通过缩进来判断哪些代码行应该组合在一起。
- 字典是从键(例如单词)到值(例如它们的频率)的映射。
- 我们必须先打开一个文件,才能开始从中读取数据。
- 文件打开后,我们可以使用方法或循环来逐行读取。
- 一些模块(如 csv 和 zipfile)是 Python 自带的,可以直接通过导入来使用。
- 其他模块,例如 matplotlib,需先安装之后才能导入和使用。