ArrayLists - Revision history

Admin: /* Python */

2019-03-12T15:54:04Z

Python

← Older revision		Revision as of 15:54, 12 March 2019
Line 89:		Line 89:
	The essence of this class is that it is a dynamically sizable, array-based structure. In the Goodrich Python book, the array-based list, emulating the built-in Python list type, is covered in Chapter 3 - the first data structure you learn about in Python is a list. It's a wonderfully simple data container. The Java version of Goodrich doesn't get around to implementing your own array-based list type until Chapter 6!		The essence of this class is that it is a dynamically sizable, array-based structure. In the Goodrich Python book, the array-based list, emulating the built-in Python list type, is covered in Chapter 3 - the first data structure you learn about in Python is a list. It's a wonderfully simple data container. The Java version of Goodrich doesn't get around to implementing your own array-based list type until Chapter 6!

	Here is an implementation of a few of the concepts from Chapter 3 in the form of the DynamicArray class, which emulates the built-in, array-based list type in its simple design: https://charlesreid1.com~~:3000~~/cs/python/src/master/arrays/DynamicArray.py		Here is an implementation of a few of the concepts from Chapter 3 in the form of the DynamicArray class, which emulates the built-in, array-based list type in its simple design: https://git.charlesreid1.com/cs/python/src/master/arrays/DynamicArray.py

	This implementation uses the ctype module to access a low-level array of Python Objects.		This implementation uses the ctype module to access a low-level array of Python Objects.

Admin at 15:53, 12 March 2019

2019-03-12T15:53:50Z

← Older revision		Revision as of 15:53, 12 March 2019
Line 11:		Line 11:
	Here is an implementation of a Python list in Java, which is pretty close in style to the Python list, which works transparently with any data so long as they have matching types.		Here is an implementation of a Python list in Java, which is pretty close in style to the Python list, which works transparently with any data so long as they have matching types.

	https://charlesreid1.com~~:3000~~/cs/java/src/master/arrays/python-list/PythonList.java		https://git.charlesreid1.com/cs/java/src/master/arrays/python-list/PythonList.java

	<pre>		<pre>

Admin: /* Flags */

2017-09-09T17:02:52Z

Flags

← Older revision		Revision as of 17:02, 9 September 2017
Line 120:		Line 120:
	==Flags==		==Flags==

	{{~~DataStructuresFlag~~}}		{{LinkedListFlag}}

	[[Category:Python]]		[[Category:Python]]

Admin: /* Python */

2017-06-03T01:34:18Z

Python

← Older revision		Revision as of 01:34, 3 June 2017
Line 93:		Line 93:
	This implementation uses the ctype module to access a low-level array of Python Objects.		This implementation uses the ctype module to access a low-level array of Python Objects.

			<pre>
			import ctypes

			class DynamicArray:
			"""
			A dynamic array class that works like a list.
			"""

			.........snip............


			def _resize(self,c):
			""" Resize to capacity c (private)"""
			print("Resizing array: {0:4d} elements, {1:5d} capacity".format(self._n,c))
			B = self._make_array(c) # bigger array
			for k in range(self._n):
			B[k] = self._A[k] # copy existing elements only
			self._A = B # forget the old array
			self._capacity = c # update capacity

			def _make_array(self,n):
			"""Make the internal array (private)"""
			return (n*ctypes.py_object)()
			</pre>

	==Flags==		==Flags==

Admin: /* Flags */

2017-06-03T00:55:27Z

Flags

← Older revision		Revision as of 00:55, 3 June 2017
Line 98:		Line 98:

	{{DataStructuresFlag}}		{{DataStructuresFlag}}

			[[Category:Python]]
			[[Category:Java]]
			[[Category:Lists]]
			[[Category:Arrays]]

Admin: /* Python */

2017-06-03T00:54:54Z

Python

← Older revision		Revision as of 00:54, 3 June 2017
Line 92:		Line 92:

	This implementation uses the ctype module to access a low-level array of Python Objects.		This implementation uses the ctype module to access a low-level array of Python Objects.



			==Flags==

			{{DataStructuresFlag}}

Admin: /* Python */

2017-06-03T00:54:39Z

Python

← Older revision		Revision as of 00:54, 3 June 2017
Line 88:		Line 88:

	The essence of this class is that it is a dynamically sizable, array-based structure. In the Goodrich Python book, the array-based list, emulating the built-in Python list type, is covered in Chapter 3 - the first data structure you learn about in Python is a list. It's a wonderfully simple data container. The Java version of Goodrich doesn't get around to implementing your own array-based list type until Chapter 6!		The essence of this class is that it is a dynamically sizable, array-based structure. In the Goodrich Python book, the array-based list, emulating the built-in Python list type, is covered in Chapter 3 - the first data structure you learn about in Python is a list. It's a wonderfully simple data container. The Java version of Goodrich doesn't get around to implementing your own array-based list type until Chapter 6!

			Here is an implementation of a few of the concepts from Chapter 3 in the form of the DynamicArray class, which emulates the built-in, array-based list type in its simple design: https://charlesreid1.com:3000/cs/python/src/master/arrays/DynamicArray.py

			This implementation uses the ctype module to access a low-level array of Python Objects.

Admin: Created page with "Array-based list data structure. ==Java== ===Built-in ArrayList type=== Java Collections uses built-in array-based list structure, ArrayList<>. Link: https://docs.oracle.co..."

2017-06-03T00:53:01Z

Created page with "Array-based list data structure. ==Java== ===Built-in ArrayList type=== Java Collections uses built-in array-based list structure, ArrayList<>. Link: https://docs.oracle.co..."

New page

Array-based list data structure.

==Java==

===Built-in ArrayList type===

Java Collections uses built-in array-based list structure, ArrayList<>. Link: https://docs.oracle.com/javase/7/docs/api/java/util/ArrayList.html

===Bringing the Python List to Java===

Here is an implementation of a Python list in Java, which is pretty close in style to the Python list, which works transparently with any data so long as they have matching types.

https://charlesreid1.com:3000/cs/java/src/master/arrays/python-list/PythonList.java

<pre>
public class PythonList {

public static void main(String[] args) {

PythonList p = new PythonList();
Random r = new Random();

int n = 50;

for(int i=0; i<100; i++ ) {
p.append(r.nextInt(6)+1);
System.out.println(p);
}
System.out.println(p);
}

///////////////////////////////////////////////////

final private int INITCAP = 10;
private Object[] data;
public int length;

public PythonList() {
length = 0;
data = new Object[INITCAP];
}

public Object get(int ix) {
return data[ix];
}

public void append(Object o) {
if(data.length==length) {
resize(data.length*2);
}
data[length] = o;
length++;
}

public void remove(int rmi) {
if(rmi>=length) {
throw new ArrayIndexOutOfBoundsException("Error accessing index "+rmi);
}
data[rmi] = null;
for(int i=rmi; i<length; i++) {
data[i] = data[i+1];
}
length--;
if(length<(data.length/4)) {
resize(data.length/2);
}
}

private void resize(int newcap) {
Object[] newarr = new Object[newcap];
for(int i=0; i<length; i++ ) {
newarr[i] = data[i];
}
data = newarr;
}

public String toString() {
return Arrays.toString(data);
}
}

</pre>

==Python==

The essence of this class is that it is a dynamically sizable, array-based structure. In the Goodrich Python book, the array-based list, emulating the built-in Python list type, is covered in Chapter 3 - the first data structure you learn about in Python is a list. It's a wonderfully simple data container. The Java version of Goodrich doesn't get around to implementing your own array-based list type until Chapter 6!