Cara menggunakan python list set slice
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Consider a list with 5 integer elements: Show
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>>> thelist = [0,5,10,15,20]Now suppose we wish to change the central three elements (5, 10 and 15, at positions 1, 2 and 3 in the list) to the values 6, 7, and 8. As with a string, we could extract the three elements with a statement like: >>> thelist[1:4] [5, 10, 15]But with a list, we can also assign values to that slice: >>> thelist[1:4] = [6,7,8] >>> thelist [0, 6, 7, 8, 20] If the number of elements in the list on the right hand side of the equal sign is not equal to the number of elements implied by the subscript of the slice, the list will expand or shrink to accomodate the assignment. (Recall that the number of elements in a slice is the higher valued subscript minus the lower valued subscript.) The following examples illustrate this point: >>> words = ['We','belong','to','the','knights','who','say','"Ni"'] >>> words[1:4] = ['are'] >>> words ['We', 'are', 'knights', 'who', 'say', '"Ni"'] >>> words[1:2] = ['are','a','band','of'] ['We', 'are', 'a', 'band', 'of', 'knights', 'who', 'say', '"Ni"']Note that when we are replacing a slice with a single element, it must be surrounded by square brackets, effectively making it into a list with one element, to avoid a TypeError exception. Assignments through slicing differ from those done with simple subscripting in that a slice can change the length of a list, while assignments done through a single subscript will always preserve the length of the list. This is true for slices where both of the subscripts are the same. Notice the difference between the two expressions shown below: >>> # using a single subscript >>> x = ['one','two','three','four','five'] >>> x[1] = ['dos','tres','cuatro'] >>> x ['one', ['dos', 'tres', 'cuatro'], 'three', 'four', 'five'] >>> # using a slice >>> x = ['one','two','three','four','five'] >>> x[1:1] = ['dos','tres','cuatro'] >>> x >>> ['one', 'dos', 'tres', 'cuatro', 'two', 'three', 'four', 'five']In the final example, we were able to insert three elements into an list without replacing any elements in the list by assigning to a slice where both subscripts were the same. Another use of slices is to make a separate modifiable copy of a list. (See Section 6.1 to understand why this is important.) In this case, you create a slice without either a starting or ending index. Python will then make a complete copy of the list >>> x = ['one','two','three'] >>> y = x[:] >>> y ['one', 'two', 'three'] One final use of slices is to remove elements from an array. If we try to replace a single element or slice of an array with an empty list, that empty list will literally replace the locations to which it's assigned. But if we replace a slice of an array with an empty list, that slice of the array is effectively removed: >>> a = [1,3,5,7,9] >>> a[2] = [] >>> a [1, 3, [], 7, 9] >>> b = [2,4,6,8] >>> b[2:3] = [] >>> b [2, 4, 8] Another way to remove items from a list is to use the del statement. You provide the del statement with the element or slice of a list which you want removed, and that element or slice is removed without a trace. So to remove the second element from the list a in the previous example, we would use the del statement as follows: >>> del a[2] >>> a [1, 3, 7, 9]The del statement is just as effective with slices: >>> nums = ['one','two','three','four','five'] >>> del nums[0:3] >>> nums ['four', 'five']In the previous example, the same result could be obtained by assigning an empty list to nums[0:3]. Next: List Operators Up: Lists, Tuples and Dictionaries Previous: List Data Contents Phil Spector 2003-11-12 Summary: in this tutorial, you’ll learn about Python list slice and how to use it to manipulate lists effectively. Introduction to Python List slice notationLists support the slice notation that allows you to get a sublist from a list:
In this syntax, the The
The slice will start from the The In addition to extracting a sublist, you can use the list slice to change the list such as updating, resizing, and deleting a part of the list. Python List slice examplesLet’s take some examples of using the list slice. 1) Basic Python list slice exampleSuppose that you have the following list of strings:
The following example uses the list slice to get a sublist from the
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The As a result, the slice creates a new list with three colors: This example doesn’t use the 2) Using Python List slice to get the n-first elements from a listTo get the n-first elements from a list, you omit the first argument:
The following example returns a list that includes the first three elements from the colors list:
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Notice that the 3) Using Python List slice to get the n-last elements from a listTo get the n-last elements of a list, you use the negative indexes. For example, the
following returns a list that includes the last 3 elements of the
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4) Using Python List slice to get every nth element from a listThe following example uses the
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5) Using Python List slice to reverse a listWhen you use a negative step, the slice includes the list of elements starting from the last element to the first element. In other words, it reverses the list. See the following example:
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6) Using Python List slice to substitute part of a listBesides extracting a part of a list, the list slice allows you to change the list element. The following example changes the first two elements in the colors list to the new values:
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7) Using Python List slice to partially replace and resize a listThe following example uses the list slice to replace the first and second elements with the new ones and also add a new element to the list:
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8) Using Python list slice to delete elementsThe
following shows how to use the list slice to delete the 3rd, 4th, and 5th elements from the
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Summary
Did you find this tutorial helpful ? How do you cut a list in Python?How to slice a list, string, tuple in Python. Basic usage of slices. [start:stop] [start:stop:step]. Extract from the end with a negative value. Negative values for start and stop. ... . Slice object by slice(). Assigning values by slices.. Slices for a list of lists.. Slices make shallow copy.. Slices for strings and tuples.. Can lists be sliced?As well as using slicing to extract part of a list (i.e. a slice on the right hand sign of an equal sign), you can set the value of elements in a list by using a slice on the left hand side of an equal sign. In python terminology, this is because lists are mutable objects, while strings are immutable. How do I slice a data list in Python?The format for list slicing is [start:stop:step]. start is the index of the list where slicing starts. stop is the index of the list where slicing ends. step allows you to select nth item within the range start to stop. How do you cut a list in half in Python?This can be done using the following steps:. Get the length of a list using len() function.. If the length of the parts is not given, then divide the length of list by 2 using floor operator to get the middle index of the list.. Slice the list into two halves using [:middle_index] and [middle_index:]. Apa itu slicing di Python?Slicing merupakan teknik memilih data dari sebuah set data. Misal kita memiliki data berat badan mahasiswa: 65, 78, 77, 100, 56. Maka jika kita urutkan maka urutan pertama adalah 65, urutan kedua adalah 78, urutan ketiga adalah 77, urutan keempat adalah 100, dan urutan terakhir adala 56.
Apa itu set pada Python?Apa Itu Tipe Data Set Python
Tipe data set merupakan tipe data yang digunakan untuk menyimpan banyak nilai dalam satu variabel dan yang tidak beraturan serta memiliki nilai yang unik (tidak ada duplikasi).
Apa itu built in pada Python?Didalam bahasa pemrograman Python terdapat dua jenis yaitu Built-In Function dan User Defined Function. Built-In Function adalah sebutan untuk fungsi yang sudah ada secara bawaan dari dalam bahasa pemrograman. Sedangkan User Defined Function adalah fungsi yang kita (sebagai programmer) membuatnya sendiri.
Apa itu Len di Python?2. Len() Kita masuk dalam pembahasan yang pertama yaitu fungsi Len(). Fungsi len() digunakan untuk mengidentifikasi dan mengetahui seberapa panjang jumlah item atau anggota pada suatu objek. Penerapan fungsi len() ini bisa dipraktekkan pada berbagai jenis data seperti data sequence dan data collection.
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