1. Introduction
Lists organize their elements by position. This mode of organization is useful when you want to locate the first element, the last element, or visit each element in a sequence. However, in some situations, the position of a datum in a structure is irrelevant; we’re interested in its association with some other element in the structure. For example, you might want to look up Ahmed’s phone number but don’t care where that number is in the phone book. A dictionary organizes information by association, not position. For example, when you use a dictionary to look up the definition of “mammal,” you don’t start at page 1; instead, you turn directly to the words beginning with “M.” Phone books, address books, encyclopedias, and other reference sources also organize information by association. In computer science, data structures organized by association are also called tables or association lists. In Python, a dictionary associates a set of keys with data values. For example, the keys in Webster’s Dictionary comprise the set of words, whereas the associated data values are their definitions. In this section, we examine the use of dictionaries in the data processing.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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