-
Notifications
You must be signed in to change notification settings - Fork 2
Expand file tree
/
Copy pathiterator-python.html
More file actions
588 lines (493 loc) · 25.5 KB
/
Copy pathiterator-python.html
File metadata and controls
588 lines (493 loc) · 25.5 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8"/>
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
<meta name="description" content="A Set can be defined as a unordered and unindexed collection of objects.
As sets are unordered so we cannot be sure about the order in which the items will appear.
In Python. sets are used to written by curly brackets{ }"/>
<meta name="keywords" content="Python Set,set in Python,set,C, C++, Python, Java, HTML, CSS, JavaScript, SQL, PHP, jQuery, XML, DOM, Bootstrap, Tutorials, Articles, Programming, training, learning, quiz, preferences, examples, code"/>
<title>Set in Python | Python Tutorials | CodeMistic</title>
<script data-ad-client="ca-pub-5352867889640158" async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
<!-- Google Tag Manager -->
<script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
})(window,document,'script','dataLayer','GTM-MCNC43J');</script>
<!-- End Google Tag Manager -->
<!-- Global site tag (gtag.js) - Google Analytics -->
<script async src="https://www.googletagmanager.com/gtag/js?id=G-YPTQSLH0XW"></script>
<script>
window.dataLayer = window.dataLayer || [];
function gtag(){dataLayer.push(arguments);}
gtag('js', new Date());
gtag('config', 'G-YPTQSLH0XW');
</script>
<!-- Favicon -->
<link rel="icon" type="img/png" href="../favicon.png"/>
<!-- FONT AWESOME -->
<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.13.1/css/all.css"
integrity="sha384-xxzQGERXS00kBmZW/6qxqJPyxW3UR0BPsL4c8ILaIWXva5kFi7TxkIIaMiKtqV1Q" crossorigin="anonymous"/>
<!-- FONTS -->
<link href="https://fonts.googleapis.com/css2?family=Kalam:wght@700&family=Ubuntu&family=Varela+Round&display=swap"
rel="stylesheet"/>
<!-- Bootstrap -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity=""
crossorigin="anonymous"/>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity=""
crossorigin="anonymous"/>
<!-- CSS -->
<link rel="stylesheet" href="../lang_styles.css"/>
</head>
<body>
<!-- Google Tag Manager (noscript) -->
<noscript><iframe src="https://www.googletagmanager.com/ns.html?id=GTM-MCNC43J"
height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript>
<!-- End Google Tag Manager (noscript) -->
<!-- NAVIGATION BAR -->
<nav class="navbar fixed-top navbar-expand-xl navbar-dark">
<a class="navbar-brand" href="../index.html">CODEMISTIC</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav ml-auto">
<li class="nav-item">
<a class="nav-link" href="../index.html">Home</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button"
data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Tutorials
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="../cpp.html">C++</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="../python.html">Python</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="../java.html">Java</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="../dsa.html">Data Structure and Algorithms</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="../tutorials.html">All Tutorials</a>
</div>
</li>
<li class="nav-item">
<a class="nav-link" href="../events.html">Events</a>
</li>
<li class="nav-item">
<a class="nav-link" href="../teen-code.html">Teen-Code</a>
</li>
<li class="nav-item">
<a class="nav-link" href="../campus.html">Campus Programme</a>
</li>
<!-- <li class="nav-item">
<a class="nav-link" href="https://docs.google.com/forms/d/e/1FAIpQLSc2O28YJpxQc6kh2tKpI_Lf5MwfwGXVnhMs0g5EEXobJ4Beeg/viewform?usp=sf_link" target="_blank">Contribute</a>
</li> -->
<li class="nav-item">
<a class="nav-link" href="../register.html">Join Our Community</a>
</li>
</ul>
</div>
</nav>
<!-- Accordion -->
<section class="lbar">
<div class="lang-img col-md-2">
<img src="../logo/python.png" alt="python" class="imghome" >
</div>
<ul id="accordion" class="accordion ml-5">
<li class=" collape in">
<div class="link">Python Introduction<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse">
<li>
<a href="start-python.html " class="closed">Getting Started</a>
</li>
<li>
<a href="keyword-and-identifiers-python.html" class="closed">Keyword and Identifiers</a>
</li>
<li>
<a href="statements-and-comments-python.html" class="closed">Statements & Comments</a>
</li>
<li>
<a href="variables-python.html" class="closed">Python Variables</a>
</li>
<li>
<a href="datatypes-python.html" class="closed">Python Datatypes</a>
</li>
<li>
<a href="type-conversion-python.html" class="closed">Python Type Conversion</a>
</li>
<li>
<a href="input-output-import-python.html" class="closed">Python I/O and import</a>
</li>
<li>
<a href="operators-python.html" class="closed">Python Operators</a>
</li>
<li>
<a href="namespace-python.html" class="closed">Python Namespace</a>
</li>
</ul>
</li>
<li>
<div class="link">Flow Control<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse">
<li>
<a href="if-else-python.html" class="closed">Getting if...else</a>
</li>
<li>
<a href="keyword-for-loop-python.html" class="closed">Python for Loop</a>
</li>
<li>
<a href="while-loop-python.html" class="closed">Python while Loop</a>
</li>
<li>
<a href="break-and-continue-python.html" class="closed">Python break and continue</a>
</li>
<li>
<a href="pass-python.html" class="closed">Python Pass</a>
</li>
</ul>
</li>
<li>
<div class="link">Python Function<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse">
<li>
<a href="functions-python.html" class="closed">Getting Functions</a>
</li>
<li>
<a href="keyword-and-arguments-python.html" class="closed">Keyword and Arguments</a>
</li>
<li>
<a href="recursion-python.html" class="closed">Python Recursions</a>
</li>
<li>
<a href="anonymous-python.html" class="closed">Anonymous Function</a>
</li>
<li>
<a href="global-local-and-nonlocal-python.html" class="closed">Global, Local and Nonlocal</a>
</li>
<li>
<a href="modules-python.html" class="closed">Python Modules</a>
</li>
<li>
<a href="package-python.html" class="closed">Python Packages</a>
</li>
</ul>
</li>
<li>
<div class="link">Python Data Types<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse">
<li>
<a href="numbers-python.html" class="closed">Python Numbers</a>
</li>
<li>
<a href="list-python.html" class="closed">Python List</a>
</li>
<li>
<a href="tuple-python.html" class="closed">Python Tuple</a>
</li>
<li>
<a href="string-python.html" class="closed">Python String</a>
</li>
<li>
<a href="set-python.html" class="closed">Python Set</a>
</li>
<li>
<a href="dictionary-python.html" class="closed">Python Dictionary</a>
</li>
</ul>
</li>
<li>
<div class="link">Python File Handeling<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse">
<li>
<a href="file-operation-python.html" class="closed">Python File Operation</a>
</li>
<li>
<a href="directory-and-file-management-python.html" class="closed">Python Directory</a>
</li>
<li>
<a href="exception-python.html" class="closed">Python Exception</a>
</li>
<li>
<a href="exception-handling-python.html" class="closed">Python Exception Handling</a>
</li>
<li>
<a href="user-defined-exception-python.html" class="closed">Python User-defined Exception</a>
</li>
</ul>
</li>
<li>
<div class="link">Python Object and Class<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse">
<li>
<a href="oop-python.html" class="closed">Python OOP</a>
</li>
<li>
<a href="class-python.html" class="closed">Python Class</a>
</li>
<li>
<a href="inheritance-python.html" class="closed">Python Inheritance</a>
</li>
<li>
<a href="multiple-inheritance-python.html" class="closed">Multiple Inheritance</a>
</li>
<li>
<a href="operator-overloading-python.html" class="closed">Operator Overloading</a>
</li>
</ul>
</li>
<li>
<div class="link">Python Advance Topics<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse show">
<li>
<a href="iterator-python.html" class="opened">Python Iterator</a>
</li>
<li>
<a href="generator-python.html" class="closed">Python Generator</a>
</li>
<li>
<a href="closure-python.html" class="closed">Python Closure</a>
</li>
<li>
<a href="decorator-python.html" class="closed">Python Decorators</a>
</li>
<li>
<a href="properties-python.html" class="closed">Python Properties</a>
</li>
<li>
<a href="regex-python.html" class="closed">Python RegEx</a>
</li>
</ul>
</li>
<li>
<div class="link">Python Date and Time<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse">
<li>
<a href="datetime-python.html" class="closed">Python datetime Module</a>
</li>
<li>
<a href="datetime.strftime()-python.html" class="closed">Python datetime.strftime()</a>
</li>
<li>
<a href="datetime.strptime()-python.html" class="closed">Python datetime.strptime()</a>
</li>
<li>
<a href="current-date-and-time-python.html" class="closed">Current Date and Time</a>
</li>
<li>
<a href="get-current-time-python.html" class="closed">Get current time</a>
</li>
<li>
<a href="timestamp-to-datetime-python.html" class="closed">Timestamp to datetime</a>
</li>
<li>
<a href="time-module-python.html" class="closed">Python Time Module</a>
</li>
<li>
<a href="time.sleep-python.html" class="closed">Python time.sleep</a>
</li>
</ul>
</li>
</ul>
</section>
<br>
<section class="para">
<!-- <div class="but mt-4">
<button class="btn btn-md btn-primary "><a href="../dsa.html"><i
class="fas fa-arrow-left "></i> Back to Index</a></button>
</div> -->
<!-- breadcrumb -->
<nav class="bdcrumb" id="bdcrumb" aria-label="breadcrumb">
<ul class="breadcrumb">
<li class="breadcrumb-item"><a href="../tutorials.html"><i class="fas fa-home"></i></a></li>
<li class="breadcrumb-item"><a href="../python.html#languages">Python Index</a></li>
<li class="breadcrumb-item active" aria-current="page">Python Iterators</li>
</ul>
</nav>
<!-- breadcrumb ending -->
<!-- HEADING -->
<br>
<div class="wrapper">
<h3>Python Iterators</h3>
<hr>
<p>An <b>iterator</b> may be defined as an object that contains countable number of values.<br>
In other words an <b>iterator</b>is an object through which we can traverse all the given values.<br>
In python, techically an <b>iterator</b> is an object which consists of <b>__iter__()</b> and <b>__next__()</b> methods.</p>
<h5>The iter() method</h5>
<p>As we know, list,tuples,dictionaries,sets are iterable objects.All these objects have their <b>iter()</b> method which is used to get an iterator.<br>Lwt's take an example of a <b>list</b>.</p>
<b>Example:</b>
<pre><code>list1 = ["january", "february", "march"]
iterator1 = iter(list1)
print(next(iterator1))
print(next(iterator1))
print(next(iterator1))
</code></pre>
<b>Output:</b>
<pre><code>january
february
march
</code></pre>
<p>In the above code, we create a list named <b>list1</b> in which we used <b>iter()</b> method to access all the elements.</p>
<p><b>Note:</b>Strings are also iterable objects.It will work same as list worked above.</p>
<h5>Using loop through an Iterator</h5>
<p>We can also use loop to iterate through the iterable objects.<br>
For example,take <b>for</b> loop in to iterate through objects.</p>
<b>Example:</b>
<pre><code>list1 = ["january", "february", "march"]
for var in list1:
print(var)
</code></pre>
<b>Output:</b>
<pre><code>january
february
march</code></pre>
<p>We can also use loops in tuple,dictionaries ,sets as well as strings.</p>
<h5>Creation of Iterators</h5>
<p>For craetion of an <b>bject/class</b> as an iterator, we have to use 2 methods here:</p>
<ol><li><b>__iter__()</b></li>
<li><b>__next__()</b></li></ol>
<p>The above methods should be implemented to the objects.</p>
<p><b>__iter__() method-</b> This method is helps us to perform the operations but it will always return the iterator object itself.</p><br>
<p><b>__next__() method-</b> This method allows us to do operations and it will return the next item in the sequence.</p><br>
<b>Example:</b>
<pre><code>class Multiple:
def __iter__(self):
self.num = 10
return self
def __next__(self):
var = self.num
self.num *= 10
return var
nclass = Multiple()
iterator = iter(nclass)
print(next(iterator))
print(next(iterator))
print(next(iterator))
print(next(iterator))
print(next(iterator))
</code></pre>
<b>Output:</b>
<pre><code>10
100
1000
10000
100000
</code></pre>
<h5>StopIteration statement</h5>
<p>This statement is used to stop the iteration at a particular condition. It will prevent the iteration to go on forever.<br>
In the __next__() method, we can add a terminating condition to raise an error if the iteration is done a specified number of times.<br></p>
<b>Syntax:</b>
<pre><code>def __next__(self):
if <b>condition</b>:
code
else:
raise <b>StopIteration</b> #The <b>raise</b> keyword is used to raise an exception.
</code></pre>
<b>Example:</b>
<pre><code>class Multiple:
def __iter__(self):
self.num = 10
return self
def __next__(self):
if self.num <=100000: #condition
var = self.num
self.num *= 10
return var
else:
raise <b>StopIteration</b>
numclass = Multiple()
iterator = iter(numclass)
for var in iterator:
print(var)
</code></pre>
<b>Output:</b>
<pre><code>10
100
1000
10000
100000
1000000
</code></pre>
<p>In the above code, we used the statement <b>StopIteration</b> to prevent our loop to run forever.</p>
</div>
<div class="but text-right">
<button class="btn btn-primary pull-right"><a href="generator-python.html">Next Topic <i
class="fas fa-arrow-right "></i><br/>Python Generator</a></button>
</div><br>
</section>
<!-- footer -->
<footer >
<div class="row footer" >
<div class="logo">
<img src="../image.png" alt="" class="f-img">
<h5>LEARN CODE DISCUSS</h5>
</div>
<div class="footer-column ">
<ul class="footer-ul">
<li class="foot-header"><strong>CodeMistic</strong></li>
<li class="f-li"><a href="../index.html" class="f-links">Home</a></li>
<li class="f-li"><a href="../team.html" class="f-links">Our Team</a></li>
<li class="f-li"><a href="../terms-and-conditions.html" class="f-links">Terms of Service</a></li>
<li class="f-li"><a href="../privacy-policy.html" class="f-links">Privacy Policy</a></li>
</ul>
</div>
<div class="footer-column ">
<ul class="footer-ul ">
<li class="foot-header"><strong>LEARN</strong></li>
<li class="f-li"><a href="../cpp.html" class="f-links">C++</a></li>
<li class="f-li"><a href="../java.html" class="f-links">Java</a></li>
<li class="f-li"><a href="../python.html" class="f-links">Python</a></li>
<li class="f-li"><a href="../dsa.html" class="f-links">DSA</a></li>
</ul>
</div>
<div class="footer-column ">
<ul class="footer-ul ">
<li class="foot-header"><strong>CONTRIBUTE</strong></li>
<li class="f-li"><a href="https://docs.google.com/forms/d/e/1FAIpQLSduxk_aP9M1lqUAebQJwRXiVm2ukmdgv3T7gjBpOsr_gdeOcQ/viewform?usp=sf_link" class="f-links" target="_blank">Write an Article/Blog</a></li>
<li class="f-li"><a href="https://docs.google.com/forms/d/e/1FAIpQLSc2O28YJpxQc6kh2tKpI_Lf5MwfwGXVnhMs0g5EEXobJ4Beeg/viewform?usp=sf_link" class="f-links" target="_blank">Internships</a></li>
<li class="f-li"><a href="https://docs.google.com/forms/d/e/1FAIpQLSe9nr_Aw0fGIqm3_xWhqEzTr3UWdOFz-pvKpQvkAsosORYq9w/viewform?usp=sf_link" class="f-links" target="_blank">Videos</a></li>
<li class="f-li"><a href="https://docs.google.com/forms/d/e/1FAIpQLScOW3hJjxxwzPYL4u51oboc4T1aDtIUEIRa20hKPKu4UlcZAA/viewform?usp=sf_link" class="f-links" target="_blank">Donations/Funds</a></li>
</ul>
</div>
</div>
<div class="footer-links" style="text-align: center;">
<!-- <h7>Connect With Us</h7><br><br> -->
<a href="https://www.facebook.com/codemistic " target="_blank "><i class="icons fa-2x fab fa-facebook "
style="color:#3b5998; "></i></a>
<a href="https://www.instagram.com/codemistic " target="_blank "><i class="icons fa-2x fab fa-instagram "
style="color:#e95950; "></i></a>
<a href="https://www.twitter.com/codemistic " target="_blank "><i class="icons fa-2x fab fa-twitter "
style="color:#8accf5; "></i></a>
<a href="https://www.linkedin.com/company/codemistic " target="_blank "><i
class="icons fa-2x fab fa-linkedin " style="color:#88b3ee; "></i></a>
<a href="https://t.me/codemistic " target="_blank "><i class="icons fa-2x fab fa-telegram "
style="color:#65adda; "></i></a>
<a href="https://www.youtube.com/channel/UCS1Iv_kkgQGDwoXtvrlwlag " target="_blank "><i
class="icons fa-2x fab fa-youtube " style="color:red; "></i></a>
<p class="foot mt-3">© Copyright : <strong>CodeMistic</strong> All Rights Reserved.</p>
</div>
</footer>
<!-- CSS Scripts -->
<script src="https://code.jquery.com/jquery-3.5.1.slim.min.js "
integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj "
crossorigin="anonymous "></script>
<script src="https://cdn.jsdelivr.net/npm/popper.js@1.16.0/dist/umd/popper.min.js "
integrity="sha384-Q6E9RHvbIyZFJoft+2mJbHaEWldlvI9IOYy5n3zV9zzTtmI3UksdQRVvoxMfooAo "
crossorigin="anonymous "></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/js/bootstrap.min.js "
integrity="sha384-OgVRvuATP1z7JjHLkuOU7Xw704+h835Lr+6QL9UvYjZE3Ipu6Tp75j7Bh/kR0JKI "
crossorigin="anonymous "></script>
<script src='https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js'></script>
<script src='../side.js'></script>
</body>
</html>