Download this page in PDF format A figure long obscured by the mists of history, American soldier and trader John Cleves Symmes enjoyed his moment of fame—and marked his place in the venerable rolls of nineteenth-century eccentrics—on 10 April On that day he mailed out from St. I declare the earth is hollow, and habitable within; containing a number of solid concentrick spheres, one within the other, and that it is open at the poles 12 or 16 degrees; I pledge my life in support of this truth, and am ready to explore the hollow, if the world will support and aid me in the undertaking. Of Ohio, Late Captain of Infantry.
Various ways to iterate over sequences The sequence functions illustrated in 4. We can randomize the contents of a list s before iterating over them, using random. We can convert between these sequence types. For example, tuple s converts any kind of sequence into a tuple, and list s converts any kind of sequence into a list.
We can convert a list of strings to a single string using the join function, e. Some other objects, such as a FreqDist, can be converted into a sequence using list or sorted and support iteration, e.
We can omit the parentheses because the comma has higher precedence than assignment. It is equivalent to the following traditional way of doing such tasks that does not use tuples notice that this method needs a temporary variable tmp. There are also functions that modify the structure of a sequence and which can be handy for language processing.
Thus, zip takes the items of two or more sequences and "zips" them together into a single list of tuples. Given a sequence s, enumerate s returns pairs consisting of an index and the item at that index. For some NLP tasks it is necessary to cut up a sequence into two or more parts.
To do this we decide the location where we want to cut the datathen cut the sequence at that location. We can also verify that the ratio of the sizes of the two pieces is what we intended. Combining Different Sequence Types Let's combine our knowledge of these three sequence types, together with list comprehensions, to perform the task of sorting the words in a string by their length.
A simple string is actually an object with methods defined on it such as split. We use a list comprehension to build a list of tupleswhere each tuple consists of a number the word length and the word, e. We use the sort method to sort the list in-place. Finally, we discard the length information and join the words back into a single string.
The underscore is just a regular Python variable, but we can use underscore by convention to indicate that we will not use its value. We began by talking about the commonalities in these sequence types, but the above code illustrates important differences in their roles.
First, strings appear at the beginning and the end: Lists and tuples are used in the middle, but for different purposes. A list is typically a sequence of objects all having the same type, of arbitrary length.
We often use lists to hold sequences of words. In contrast, a tuple is typically a collection of objects of different types, of fixed length.
We often use a tuple to hold a record, a collection of different fields relating to some entity. This distinction between the use of lists and tuples takes some getting used to, so here is another example: An individual entry is represented as a tuple because it is a collection of objects with different interpretations, such as the orthographic form, the part of speech, and the pronunciations represented in the SAMPA computer-readable phonetic alphabet http: Note that these pronunciations are stored using a list.
Note A good way to decide when to use tuples vs lists is to ask whether the interpretation of an item depends on its position.I take another personal day without giving a reason, an act of defiance that I fear is transparent. I spend the morning drinking coffee and skimming breathless tech press, then creep downtown to spend the afternoon in back-to-back interviews at a peanut-size start-up.
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Planning and designing library buildings and services. Books, journal articles and online resources on key aspects of library planning, service design, design and building, and designing for inclusion. Essay on Selection for Libraries - Selection is the branch of collection management concerned with deciding which items will be added to the library collection and made available to the library’s users (Kennedy, , p).
“The Academic library in the 21st Century - what need for physical space?” of the Purdue University Libraries. Please contact [email protected] for additional information. Helen King, "“The Academic library in the 21st Century - what need for physical space?”." Proceedings of the IATUL Conferences.
sufficient space. Six libraries. A library is a collection of sources of information and similar resources, made accessible to a defined community for reference or borrowing. It provides physical or digital access to material, and may be a physical building or room, or a virtual space, or both.
A library's collection can include books, periodicals, newspapers, manuscripts, films, maps, prints, documents, microform, CDs.