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Articles by Gireesha Devara
Page 3 of 18
How to wrap python object in C/C++?
To wrap existing C or C++ functionality in Python, there are number of options available, which are: Manual wrapping using PyMethodDef and Py_InitModule, SWIG, Pyrex, ctypes, SIP, Boost.Python, and pybind1. Using the SWIG Module Let’s take a C function and then tune it to python using SWIG. The SWIG stands for “Simple Wrapper Interface Generator”, and it is capable of wrapping C in a large variety of languages like python, PHP, TCL etc. Example Consider simple factorial function fact() in example.c file. /* File : example.c */ #include // calculate factorial int fact(int n) ...
Read MoreHow to create Python objects based on an XML file?
XML (Extensible Markup Language), which is a markup−language that is used to structure, store, and transfer data between systems. At some point we need to read/write the XML data using the Python language. By using the untangle library we can create Python objects based on an XML file. The untangle is a small Python library which converts an XML document to a Python object. The untangle has a very simple API. We just need to call the parse() function to get a Python object. Syntax untangle.parse(filename, **parser_features) Parameters Filename: it can be a XML string, a XML filename, ...
Read MoreIs there any Python object inspector?
In python there is no built−in or normal function that acts as an object inspector. But we can use functions like type(), help(), dir(), vars() or modules like inspect are used to find the attributes, properties and methods of any object. Also we have other functions like id(), getattr(), hasattr(), globals(), locals(), callable() are useful in looking inside an object to know its attributes and methods. Here we will inspect the objects using some built−in functions. Before that we will create a simple python class and its objects, to refer throughout this article. Following is the syntax to defing ...
Read MoreHow to prevent loops going into infinite mode in Python?
In python the while loop needs to be controlled by making some provision inside the body of the loop to drive the condition mentioned in the beginning to false. This is usually done by keeping count of iterations. If the while loop condition never evaluates to False, then we will have an infinite loop, which is a loop that never stops automatically, in this case we need to interrupt externally. count=0 while condition: stmt1 stmt2 . . count=count+1 Example Let’s take an example and ...
Read MoreHow to convert float to integer in Python?
In python there are two number data types: integers and floats. In general integers do not have any decimal points and base value is 10 (i.e., Decimal). Whereas floats have decimal points. Python provides some built−in methods to convert floats to integers. In this article we will discuss some of them. Using the int() function The int() function converts the floating point numbers to integers, by removing the decimals and remains only the integer part. Also the int() function does not round the float values like 49.8 up to 50. Example In the example the data after the decimal ...
Read MoreHow to convert an integer to a character in Python?
To convert an integer to a character in Python, we can use the chr() method. The chr() is a Python built−in method that returns a character from an integer. The method takes an integer value and returns a unicode character corresponding to that integer. Syntax char(number) Parameter The method takes a single integer between the range of 0 to 1, 114, 111. Return Value A unicode character of the corresponding integer argument. And it will raies a ValueError if we pass an out of range value (i, e. range(0x110000)). Also it will raise TypeError − for a non−integer argument. ...
Read MoreNegative transformation of an image using Python and OpenCV
An image with reversed brightness is referred a negative image, in which the light parts of the image appear dark and the darker parts appear lighter. The negative transformation of a colored image (RGB image) will be reversed, with red areas appearing cyan, greens appearing magenta, and blues appearing yellow. In Medical Imaging, Remote Sensing, and some other applications negative transformation is widely used. It also helps to find the details from the darker regions of the image. The negative transformation function is − As we know that an 8-bit image has a max intensity value is 255, therefore ...
Read MoreGet video duration using OpenCV Python
OpenCV is an Open Source Computer Vision Library in python. It provides numerous functions to perform various Image and video processing operations. The library uses the Numpy module to represent all the video frames and images as a ndarray type. It needs the numpy library, we need to make sure that the numpy module is also installed in our python interpreter. In this article, we will see different ways to get the duration of a video using the python OpenCV module. The OpenCV provides a VideoCapture.get() method to get the specified property of a video by passing one of the ...
Read MoreDraw a triangle with centroid using OpenCV
The centroid is also called the geometric center; it is defined as the center point of the object. Whereas the centroid of a triangle is defined as the point of intersection of all three medians of a triangle. Calculating the Centroid of a triangle: Let’s consider an ABC triangle, the three vertices of the triangle are A(x1, y1), B(x2, y2), and C(x3, y3). Then the centroid of a triangle can be calculated by taking the average of the x and y coordinates of all three vertices. centroid of a triangle = ((x1+x2+x3)/3 , (y1+y2+y3)/3 ) In ...
Read MoreDrawing a cross on an image with OpenCV
OpenCV is an Open Source Computer Vision Library in python. It provides numerous functions to perform various Image and video processing operations. The library uses the Numpy module to represent all the video frames and images as a ndarray type. It needs the numpy library, we need to make sure that the numpy module is also installed in our python interpreter. In this article, we will see different ways to draw a cross on an image using OpenCV Python. Let’s observe the input-output scenario to understand how to draw a cross on an image. Input Output Scenarios Assuming we have ...
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