Question

我有一个本地存储的json文件，大约有3万条记录。我想分批显示它们，以便用户在查看记录时可以前进和后退。为了使程序的大小在编译后保持较小，我尝试为此不使用pandas。

为了更好地说明这一点，以下是我目前在想的事情，使用tkinter作为显示示例：

import tkinter as tk
from tkinter import ttk

root = tk.Tk()

data = {i:[i,i] for i in range(1,10001)} #dummy data; actual key is not a integer

class Tree(ttk.Treeview):
    def __init__(self,master=None,**kwargs):
        ttk.Treeview.__init__(self,master,**kwargs)
        self.height = kwargs.get("height",20)
        self["columns"] = ("No.","Item")
        start_index = 0
        self.page = 0
        for k, v in data.items():
            self.insert("", tk.END, text=k, value=v)
            start_index += 1
            if start_index == self.height:
                break

    def forward(self):
        self.delete(*self.get_children())
        start_index = 0
        for k, v in data.items():
            if (self.page+1)*self.height <= start_index < (self.page+2)*self.height:
                self.insert("", tk.END, text=k, value=v)
            elif start_index > (self.page+2)*self.height:
                self.page+=1
                current.config(text=f"Page {self.page+1}")
                break
            start_index += 1

    def backward(self):
        if self.page == 0: return
        self.delete(*self.get_children())
        start_index = 0
        for k, v in data.items():
            if (self.page-1)*self.height <= start_index < self.page*self.height:
                self.insert("", tk.END, text=k, value=v)
            elif start_index > self.page*self.height:
                self.page-=1
                current.config(text=f"Page {self.page+1}")
                break
            start_index += 1

    def jump_page(self, event=None):
        if entry.get().isnumeric():
            self.page = int(entry.get())-2
            self.forward()

tree = Tree(root,height=20)
tree.pack()

frame = tk.Frame(root)
frame.pack(side="bottom")

ttk.Button(frame,text="Backward",command=tree.backward).grid(row=0,column=1)
ttk.Button(frame,text="Forward",command=tree.forward).grid(row=0,column=2)
tk.Label(frame,text="Jump to page:").grid(row=0,column=3,padx=2)
entry = ttk.Entry(frame,width=4)
entry.grid(row=0,column=4)
entry.bind("<Return>", tree.jump_page)
current = tk.Label(frame,text="Page 1",width=12)
current.grid(row=0,column=0)

root.mainloop()

我的问题：这是正确的方法吗？我依靠的是从3.6开始就对字典进行插入排序，因此我不确定这样做是否是一个好习惯。另外，我每次都必须遍历整个字典（尽管在获取结果时它可能会中断）。

为完整起见，这是我在pandas中的做法：

import pandas as pd

s = pd.Series(data, name="No.")

class Tree(ttk.Treeview):
    ...
    def pd_forward(self):
        x = s.iloc[(self.page+1)*self.height:(self.page+2)*self.height]
        if not len(x): return
        self.delete(*self.get_children())
        for k, v in x.items():
            self.insert("", tk.END, text=k, value=v)
        self.page+=1
        current.config(text=f"Page {self.page+1}")

如何来回遍历字典

0 个答案: