如何计算Pandas中分组行之间的差异

Question

我有一个数据集，其中包含每篇文章的视图数

我试图计算每个故事每天额外的浏览量，这样我就可以绘制它

我只为了一个故事就成功了

storyviews = stats[['title', 'views']].sort_values(by=['title','views'])
storyviews = stats[stats["title"] == "Getting Started with TDD"]
storyviews = storyviews[["title","views"]].sort_values(by=['title','views'])
difference = storyviews.set_index('title').diff()
difference = difference.dropna(subset=['views'])
difference

我得到了正确的结果

有没有一种方法可以一次完成所有的故事

数据集

y,m,d,mediumID,title,link,publication,mins,views,reads,readRatio,fans,pubDate,liveDate
2020,06,30,a1777d8bf7e,Swift — Filtering: A Real Example,https://levelup.gitconnected.com/swift-filtering-a-real-example-a1777d8bf7e,Level Up Coding,4 min read,35,13,37.142857142857146,1,2020-06-17,2020-06-26
2020,06,30,6f5fc68b0b43,SwiftUI 2: an overview,https://levelup.gitconnected.com/swiftui-2-an-overview-6f5fc68b0b43,Level Up Coding,3 min read,43,22,51.16279069767442,2,2020-06-24,2020-06-24
2020,07,01,a1777d8bf7e,Swift — Filtering: A Real Example,https://levelup.gitconnected.com/swift-filtering-a-real-example-a1777d8bf7e,Level Up Coding,4 min read,37,13,35.13513513513514,1,2020-06-17,2020-06-26
2020,07,01,6f5fc68b0b43,SwiftUI 2: an overview,https://levelup.gitconnected.com/swiftui-2-an-overview-6f5fc68b0b43,Level Up Coding,3 min read,57,29,50.87719298245614,10,2020-06-24,2020-06-24
2020,07,02,a1777d8bf7e,Swift — Filtering: A Real Example,https://levelup.gitconnected.com/swift-filtering-a-real-example-a1777d8bf7e,Level Up Coding,4 min read,37,13,35.13513513513514,1,2020-06-17,2020-06-26
2020,07,02,6f5fc68b0b43,SwiftUI 2: an overview,https://levelup.gitconnected.com/swiftui-2-an-overview-6f5fc68b0b43,Level Up Coding,3 min read,76,43,56.578947368421055,15,2020-06-24,2020-06-24
2020,07,03,a1777d8bf7e,Swift — Filtering: A Real Example,https://levelup.gitconnected.com/swift-filtering-a-real-example-a1777d8bf7e,Level Up Coding,4 min read,40,13,34.21052631578947,1,2020-06-17,2020-06-26
2020,07,03,6f5fc68b0b43,SwiftUI 2: an overview,https://levelup.gitconnected.com/swiftui-2-an-overview-6f5fc68b0b43,Level Up Coding,3 min read,152,70,46.05263157894737,20,2020-06-24,2020-06-24

谢谢， 尼古拉斯

Answer 1

所以你只是想得到每个标题的所有浏览量的总和？以下是从数据帧使用字典转换的单向方法：

在for循环

...
dict = df.groupby('title').groups
for key in dict:
    numpyarray_diff_between = np.diff(np.array(list(dict[key])))
...

Answer 2

你能试一试吗

cols = ['title', 'views']
storyviews = stats[cols].sort_values(by=cols)
res = storyviews.set_index('title').groupby('title', sort=False).diff().dropna()

输出：

                                   views
title                                   
SwiftUI 2: an overview              14.0
SwiftUI 2: an overview              19.0
SwiftUI 2: an overview              76.0
Swift — Filtering: A Real Example     2.0
Swift — Filtering: A Real Example     0.0
Swift — Filtering: A Real Example     3.0

对于绘制图例，标题…，您可能需要问另一个问题。我没有答案。为了让你开始情节，试试这个

res.reset_index().groupby('title', sort=False).plot()