如何在cakephp中显示最后一个链接(How to show the last link in cakephp)

 您可以使用： 
 
df = DataFrame(
  cat = ["a", "b", "c","a"],
  prices = [1,2,3,4],
  vol    = [10,20,30,40],
)

df2 = by(df, :cat) do sub
      t = DataFrame(prices=mean(sub[:prices]), vol=sum(sub[:vol]))
end

df2

3×3 DataFrames.DataFrame
│ Row │ cat │ prices │ vol │
├─────┼─────┼────────┼─────┤
│ 1   │ "a" │ 2.5    │ 50  │
│ 2   │ "b" │ 2.0    │ 20  │
│ 3   │ "c" │ 3.0    │ 30  │
 
 如果您必须按日/月/等计算一些总数，您可能也会对此答案感兴趣。 

You can use by:
 
df = DataFrame(
  cat = ["a", "b", "c","a"],
  prices = [1,2,3,4],
  vol    = [10,20,30,40],
)

df2 = by(df, :cat) do sub
      t = DataFrame(prices=mean(sub[:prices]), vol=sum(sub[:vol]))
end

df2

3×3 DataFrames.DataFrame
│ Row │ cat │ prices │ vol │
├─────┼─────┼────────┼─────┤
│ 1   │ "a" │ 2.5    │ 50  │
│ 2   │ "b" │ 2.0    │ 20  │
│ 3   │ "c" │ 3.0    │ 30  │
 
If you have to make some totals by day/months/etc you may be interested also in this so answer.