操做一個二維數據

問題

定義一個20*5的二維數組，用來存儲某班級20位學員的5門課的成績；這5門課按存儲順序依次爲：core C++，coreJava，Servlet，JSP和EJB。

（1）循環給二維數組的每個元素賦0~100之間的隨機整數。

（2）按照列表的方式輸出這些學員的每門課程的成績。

（3）要求編寫程序求每一個學員的總分，將其保留在另一個一維數組中。

（4）要求編寫程序求全部學員的某門課程的平均分。

解決（python）

#! /usr/bin/env python
#coding:utf-8

from __future__ import division
import random


def score(score_list,course_list,student_num):
    course_num = len(course_list)

    every_score = [[score_list[j][i] for j in range(course_num)] for i in range(student_num)]

    every_total = [sum(every_score[i]) for i in range(student_num)]

    ave_course = [sum(score_list[i])/len(score_list[i]) for i in range(len(score_list))]

    return (every_score,every_total,ave_course)

if __name__=="__main__":

    course_list = ["C++","Java","Servlet","JSP","EJB"]
    student_num = 20

    score_list = [[random.randint(0,100) for i in range(student_num)] for j in range(len(course_list))]
    for i in range(len(course_list)):
        print "score of every one in %s:"%course_list[i]
        print score_list[i]

    every_score,every_total,ave_one_course = score(score_list,course_list,student_num)
    print "\n"
    print "NEXT IS EVERY ONE SCORE IN EVERY COURSE:"
    for name in course_list:
        print name,
    print "\t"
    print every_score
    print "\n"
    print "every one all score:\t",every_total
    print "every course of average score:\t",ave_one_course

qiwsir#gmail.com (# to @)

解法 (racket 5.2.1)

#lang racket

(define (2d-list)
  (let*
    ([rand-100 (lambda () (random 101))]
     [nth-picker (lambda (n) (lambda (l) (list-ref l n)))]
     [average (lambda (number-list) (exact->inexact (/ (apply + number-list) (length number-list))))]
     [course-list (list "coreC++" "coreJava" "Servlet" "JSP" "EJB")]
     [score-list (for/list ([i 20]) (for/list ([j 5]) (rand-100)))]
     [score-by-course-list (for/list ([i 5]) (list ((nth-picker i) course-list) (map (nth-picker i) score-list)))]
     [score-by-student-list (for/list ([i 20]) (list-ref score-list i))]
     [total-by-student-list (for/list ([i 20]) (apply + (list-ref score-list i)))]
     [average-by-course-list (for/list ([i 5]) (list ((nth-picker i) course-list) (average (map (nth-picker i) score-list))))])
    (for ([i 5]) 
      (display "score of every one in ")
      (displayln (first ((nth-picker i) score-by-course-list)))
      (displayln (second ((nth-picker i) score-by-course-list))))
    (displayln "")
    (displayln "NEXT IS EVERY ONE SCORE IN EVERY COURSE: ")
    (displayln course-list)
    (for ([i 10]) 
      (displayln (list-ref score-by-student-list i)))
    (displayln "")
    (displayln "every one all score: ")
    (displayln total-by-student-list)
    (displayln "")
    (displayln "every course of average score: ")
    (displayln average-by-course-list)))

; 調用函數, 正常時應輸出相似以下結果
;score of every one in coreC++
;(12 58 60 28 78 23 34 83 19 83 78 26 51 94 93 74 53 89 8 23)
;... ...
;NEXT IS EVERY ONE SCORE IN EVERY COURSE: 
;(coreC++ coreJava Servlet JSP EJB)
;(12 49 75 88 68)
;(58 78 6 88 81)
;... ...
;every one all score: 
;(292 311 370 241 289 250 254 258 147 232 271 170 224 248 317 286 246 270 186 212)
;
;every course of average score: 
;((coreC++ 53.35) (coreJava 53.9) (Servlet 51.95) (JSP 49.6) (EJB 44.9))
(2d-list)