نوشته های محمدحسین ملک‌پور

Model-based vs Instance-based Learning

محمدحسین ملک‌پور — Sun, 02 May 2021 19:23:41 +0430

In instance-based learning there are normally no parameters to tune, the system is normally hard coded with priors in form of fixed weights or some algorithms like tree search based algorithms. Such a system normally does what is known as lazy learning by absorbing the training data instances and using those data instances for inference.For example, in scale invariant feature transform (SIFT), the recognition pipeline is hard coded. All it does during learning is to index descriptors into an indexing data structure such as a kd-tree together with some geometric information. That information is then directly used during inference to recognize instances of objects.Thus instance-based learning is just about storing the training data instances. Though the training data itself can be preprocessed in many ways and stored in memory.In model-based learning, we are talking more about reinforcement learning (RL). In model-based RL an agent builds a model of the environment in which it exists so that it can use that model to infer which actions to take in that environment that lead to desired outcomes in order to achieve a given goal.Model-based learning can also be seen as the opposite of instance-based learning. In model-based learning there are parameters to tune. These parameters with optimal settings are supposed to model the problem as accurately as possible thus learning is not simply about memorization but rather more about searching for those optimal parameters.

مقایسه 6 کتابخانه معروف پایتون NLP

محمدحسین ملک‌پور — Sun, 02 Feb 2020 17:09:18 +0330

General overviewNLTK (Natural Language Toolkit) is used for such tasks as tokenization, lemmatization, stemming, parsing, POS tagging, etc. This library has tools for almost all NLP tasks.Spacy is the main competitor of the NLTK. These two libraries can be used for the same tasks.Scikit-learn provides a large library for machine learning. The tools for text preprocessing are also presented here.Gensim is the package for topic and vector space modeling, document similarity.The general mission of the Pattern library is to serve as the web mining module. So, it supports NLP only as a side task.Polyglot is the yet another python package for NLP. It is not very popular but also can be used for a wide range of the NLP tasks.

10 نکته و ترفند پایتون برای برنامه‌نویسان مبتدی

محمدحسین ملک‌پور — Mon, 21 Oct 2019 02:19:57 +0330

Python is an interpreted, object-oriented, high-level programming language with dynamic semantics.In-Place Swapping Of Two Numbers | تعویض دو عدد در یک خطورودی:x, y = 10, 20 print(x, y) x, y = y, x print(x, y)خروجی:10 2020 10(اعداد از راست به چپ خوانده شود)Reversing a string in Python | معکوس کردن یک رشتهورودی:a = "Virgool" print("Reverse is", a[::-1])خروجی:Reverse is loogriVCreate a single string from all the elements in list | ساختن یک رشته از اعضای یک لیستورودی:a = ["Vir", "go", "ol"] print(" ".join(a))خروجی:VirgoolChaining Of Comparison Operators | تغییر اپراتورهای مقایسه‌ایورودی:n = 10 result = 1 < n < 20 print(result) result = 1 > n <= 9 print(result)خروجی:TrueFalsePrint The File Path Of Imported Modules | یافتن مسیر نصب فایل ماژول‌های استفاده شدهورودی:import os; import socket; print(os) print(socket)خروجی:Use Of Enums In Python | استفاده از داده شمارشیورودی:class MyName: x, y, z = range(3) obj = MyName() print(obj.x) print(obj.y) print(obj.z)خروجی:012Return Multiple Values From Functions | بازگرداندن مقادیر متعدد توسط تابعورودی:def x(): return 1, 2, 3, 4 a, b, c, d = x() print(a, b, c, d)خروجی:1 2 3 4 (اعداد از راست به چپ خوانده شود)Find The Most Frequent Value In a List | یافتن بیشترین ارزش در لیستورودی:test = [1, 2, 3, 4, 2, 2, 3, 1, 4, 4, 4] print(max(set(test), key = test.count))خروجی:4Check The Memory Usage Of An Object | یافتن مقدار حافظه استفاده شده توسط یک شیورودی:import sys x = 1 print(sys.getsizeof(x))خروجی:28Print string N times | چاپ متعدد یک رشتهورودی:n = 2; a ="Virgool" print(a * n);خروجی:VirgoolVirgool