NLP Academy · 课时

构建第一个词频表

统计每个词语出现的频率

构建第一个词频表 是 CoddyKit 上的免费 NLP Academy 课时。这是第 4 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 NLP Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 NLP Academy 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

What Is a Frequency Table?

A frequency table maps each word to how many times it appears. It is the foundation of nearly every text analysis. 📊

Start With Tokens

First turn text into a list of words, then lowercase them so The and the count as the same token.

words = text.lower().split()

Count With a Dictionary

A Python dictionary stores word to count pairs. You loop through words and add one each time a word appears.

freq = {}
for w in words:
    freq[w] = freq.get(w, 0) + 1

The get Trick

Using get with a default of zero avoids errors when a word is seen for the first time. It keeps the loop clean.

freq[w] = freq.get(w, 0) + 1

Counter Does It for You

The Counter class from collections builds the whole table in one line, no manual loop needed.

from collections import Counter
freq = Counter(words)

Look Up a Word

With the table built, reading a count is instant. Just index the word and you get its frequency.

print(freq["the"])  # how many times the appears

Find the Most Common

Counter's most_common method returns the top words and their counts, already sorted from highest to lowest.

print(freq.most_common(3))

Stopwords Dominate

The top of almost every table is stopwords like the, of, and a. They are frequent but carry little meaning.

Sort Your Own Dictionary

To rank a plain dict, sort its items by value. The sorted function with a key gives you the order you want.

ranked = sorted(freq.items(), key=lambda x: x[1], reverse=True)

Frequencies Power Features

This table is the seed of bag-of-words, where word counts become the numbers that machine learning models read.

Loop to Print the Table

Iterate over the items to display each word beside its count, giving you a readable summary of the document.

for word, n in freq.items():
    print(word, n)

Quick Check

Pick the fastest way to build a word count table.

Recap: Your Frequency Table

You built a frequency table with a dict or Counter, ranked the top words, and saw how counts feed bag-of-words features. 🎉

常见问题解答

「构建第一个词频表」课时是免费的吗？

是的 — 「构建第一个词频表」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 NLP Academy 课程的其余内容，请升级到 CoddyKit PRO。 NLP Academy 课程共包含 4 节课。

「构建第一个词频表」这节课中我会学到什么？

统计每个词语出现的频率你通过在浏览器中直接运行的动手代码来练习 NLP Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 NLP Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 NLP Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 4 节课，共 4 节。

「构建第一个词频表」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 NLP Academy 课中编写并运行代码吗？

能。每节 NLP Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

此课程中的所有课时

← 返回 NLP Academy