使用python已知平均數求隨機數

問題描述：產生40個數，范圍是363-429之間，平均值為402

思路：

1 產生一個隨機數

2 使用平均數減去隨機數求出第二個數，生成20組

3 將排序打亂

# -*- coding: cp936 -*-
import random
import string

###################產生隨機整數###################
###################第一個數隨機產生，第二個使用平均數求出###################
#count 數字的個數
#average 平均數
#begin 起始區間
#end 結束區間
def int_random (count, average, begin, end):

    #print "wzh_random"
    numarr = [0 for x in range(2)];
    i = 0;
    while (1):
 
      num_first = random.randrange(begin, end);
 
      #第二個數
      num_second = average * 2 - num_first;

      if (num_second >= begin and num_second <= end):
          numarr[i] = num_first;
          i = i + 1;
          numarr[i] = num_second;
          break

    return numarr;

###################產生隨機數###################
###################第一個數隨機產生，第二個使用平均數求出###################
#count 數字的個數
#average 平均數
#begin 起始區間
#end 結束區間
def float_random (count, average, begin, end):

    #print "wzh_random"
    numarr = [0 for x in range(2)];
    i = 0;
    while (1):
 
      num = random.uniform(begin, end);
      #取兩位小數
      num_first = round(num, 2);

      #第二個數
      num_second = average * 2 - num_first;

      if (num_second >= begin and num_second <= end):
          numarr[i] = num_first;
          i = i + 1;
          numarr[i] = num_second;
          break

    return numarr;



###################寫文件###################
def write_file (filename, content):
    fo = open (filename, "ab");
    fo.write(content);
    fo.close();

def show_list (list):
    for i in list:
        print i,
    print;

###################主函數調用產生整形隨機數###################
#40個數字，平均數400，363 - 429 之間
def test_random_int():
    count = 40;
    average = 402;
    begin = 363;
    end = 429;
    numarr_count = 0;
    numarr = [0 for x in range(count)];
    for i in range (count / 2):
        list = int_random (40, 402, 363, 429)
        j = 0;
        for j in range (len(list)):
             numarr[numarr_count] = list[j];
             numarr_count += 1;
    content = '';
    #打亂排序
    print "數據未打亂：";
    show_list (numarr)
    random.shuffle(numarr);
    print "數據打亂：";
    show_list (numarr)
    for i in numarr:
        content = content + ' ' + str(i);
    #print content;
    #追加寫入文件
    filename = "test.txt";
    print "文件名稱：",filename;
    write_file (filename, content)
    write_file (filename, "\n");

###################主函數調用產生實型隨機數###################
#40個數字，平均數400，363 - 429 之間
def test_random_float():
    count = 40;
    average = 402;
    begin = 363;
    end = 429;
    numarr_count = 0;
    numarr = [0 for x in range(count)];
    for i in range (count / 2):
        list = float_random (40, 402, 363, 429)
        j = 0;
        for j in range (len(list)):
             numarr[numarr_count] = list[j];
             numarr_count += 1;
    content = '';
    #打亂排序
    print "數據未打亂：";
    show_list (numarr)
    random.shuffle(numarr);
    print "數據打亂：";
    show_list (numarr)
    for i in numarr:
        content = content + ' ' + str(i);
    #print content;
    #追加寫入文件
    filename = "test.txt";
    print "文件名稱：",filename;
    write_file (filename, content)
    write_file (filename, "\n");

#調用測試產生整形隨機數
test_random_int();
#調用測試產生實型隨機數
test_random_float();