字典實例：統計詞頻

import turtle

##全局變量##
#詞頻排列顯示個數
count = 10
#單詞頻率數組-作爲y軸數據
data = []
#單詞數組-作爲x軸數據
words = []
#y軸顯示放大倍數-可以根據詞頻數量進行調節
yScale = 6
#x軸顯示放大倍數-可以根據count數量進行調節
xScale = 30

################# Turtle Start  ####################  
#從點(x1,y1)到(x2,y2)繪製線段
def drawLine(t, x1, y1, x2, y2):
    t.penup()
    t.goto (x1, y1)
    t.pendown()
    t.goto (x2, y2)

# 在座標(x,y)處寫文字
def drawText(t, x, y, text):
    t.penup()
    t.goto (x, y)
    t.pendown()
    t.write(text)

def drawGraph(t):
    #繪製x/y軸線
    drawLine (t, 0, 0, 360, 0)
    drawLine (t, 0, 300, 0, 0)

    #x軸: 座標及描述
    for x in range(count):
        x=x+1 #向右移一位,爲了不畫在原點上
        drawText(t, x*xScale-4, -20, (words[x-1]))
        drawText(t, x*xScale-4, data[x-1]*yScale+10, data[x-1])
    drawBar(t)

#繪製一個柱體
def drawRectangle(t, x, y):
    x = x*xScale
    y = y*yScale#放大倍數顯示
    drawLine(t, x-5, 0, x-5, y)
    drawLine(t, x-5, y, x+5, y)
    drawLine(t, x+5, y, x+5, 0)
    drawLine(t, x+5, 0, x-5, 0)

#繪製多個柱體
def drawBar(t):
    for i in range(count):
        drawRectangle(t, i+1, data[i])    
################# Turtle End  ####################


#對文本的每一行計算詞頻的函數
def processLine(line, wordCounts):
    #用空格替換標點符號
    line = replacePunctuations(line)
    #從每一行獲取每個詞
    words = line.split() 
    for word in words:
        if word in wordCounts:
            wordCounts[word] += 1
        else:
            wordCounts[word] = 1

#空格替換標點的函數
def replacePunctuations(line):
    for ch in line:
        if ch in "~@#$%^&*()_-+=<>?/,.:;{}[]|\'""":
            line = line.replace(ch, " ")
    return line

def main():
    #用戶輸入一個文件名
    filename = input("enter a filename:").strip()
    infile = open(filename, "r")

    #建立用於計算詞頻的空字典
    wordCounts = {}
    for line in infile:
        processLine(line.lower(), wordCounts)

    #從字典中獲取數據對
    pairs = list(wordCounts.items())

    #列表中的數據對交換位置,數據對排序
    items = [[x,y]for (y,x)in pairs] 
    items.sort() 

    #輸出count個數詞頻結果
    for i in range(len(items)-1, len(items)-count-1, -1):
        print(items[i][1]+"\t"+str(items[i][0]))
        data.append(items[i][0])
        words.append(items[i][1])

    infile.close()

    #根據詞頻結果繪製柱狀圖
    turtle.title('詞頻結果柱狀圖')
    turtle.setup(900, 750, 0, 0)
    t = turtle.Turtle()
    t.hideturtle()
    t.width(3)
    drawGraph(t)

#調用main()函數
main()

列表中數據對交換位置：
示例如下：

>>>passwd={"China":"BigCountry","Korean":"SmallCountry","France":"MediumCountry"}
>>> pairs=list(passwd.items())
>>>items = [[x,y] for (y,x) in pairs]
>>>print(items)

運行結果：

[['BigCountry', 'China'], ['SmallCountry', 'Korean'], ['MediumCountry', 'France']]