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How to replace NA values with zeros in an R data frame?
We can replace all NA values by using is.na functionExample> Data df df V1 V2 V3 V4 V5 V6 V7 V8 V9 V10 1 9 7 3 0 3 7 7 3 9 9 2 9 2 3 0 2 0 1 4 6 7 3 5 0 9 2 4 8 8 7 NA 5 4 7 3 1 2 6 NA 7 1 1 8 5 3 2 9 6 4 7 0 5 6 1 6 8 5 6 5 3 9 6 0 7 0 7 8 3 4 NA NA 0 2 4 2 NA 8 6 9 9 9 4 0 6 1 7 NA 9 5 5 NA 8 1 NA 0 9 9 3 10 1 1 0 7 1 1 4 1 2 1Replacing NA’s by 0’s> df[is.na(df)] df V1 V2 V3 V4 V5 V6 V7 V8 V9 V10 1 9 7 3 0 3 7 7 3 9 9 2 9 2 3 0 2 0 1 4 6 7 3 5 0 9 2 4 8 8 7 0 5 4 7 3 1 2 6 0 7 1 1 8 5 3 2 9 6 4 7 0 5 6 1 6 8 5 6 5 3 9 6 0 7 0 7 8 3 4 0 0 0 2 4 2 0 8 6 9 9 9 4 0 6 1 7 0 9 5 5 0 8 1 0 0 9 9 3 10 1 1 0 7 1 1 4 1 2 1
Read MoreHow to drop data frame columns in R by using column name?
Columns of a data frame can be dropped by creating an object of columns that we want to drop or an object of columns that we want to keep.Example> df keeps df[keeps] Var3 Var4 1 21 31 2 22 32 3 23 33 4 24 34 5 25 35 6 26 36 7 27 37 8 28 38 9 29 39 10 30 40
Read MoreHow to extract p-value and R-squared from a linear regression in R?
We can use regression model object name with $r.squared to find the R-squared and a user defined function to extract the p-value.ExampleExtracting R-Squared> x y LinearRegression summary(LinearRegression)$r.squared [1] 0.2814271Extracting p-value> Regressionp
Read MoreHow to sort a data frame in R by multiple columns together?
We can sort a data frame by multiple columns using order function.ExampleConsider the below data frame −> df df x1 x2 x3 x4 1 Hi A 4 9 2 Med B 7 5 3 Hi D 5 7 4 Low C 3 4Let’s say we want to sort the data frame by column x4 in descending order then by column x1 in ascending order.It can be done follows −> df[with(df, order(-x4, x1)), ] x1 x2 x3 x4 1 Hi A 4 9 3 Hi D 5 7 2 Med B 7 5 4 Low C 3 4We can do ...
Read MoreC++ Program to Compute the Area of a Triangle Using Determinants
In this section we will see how to find the area of a triangle in 2D coordinate space using matrix determinants. In this case we are considering the space is 2D. So we are putting each points in the matrix. Putting x values at the first column, y into the second and taking 1 as the third column. Then find the determinant of them. The area of the triangle will be half of the determinant value. If the determinant is negative, then simply take the absolute value of it.$$Area\:=\:absolute\:of\begin{pmatrix}\frac{1}{2} \begin{vmatrix} x_1\:\:y_1\:\:1 \ x_2\:\:y_2\:\:1 \ x_3\:\:y_3\:\:1 \end{vmatrix} \end{pmatrix}$$Here we are assuming ...
Read MoreMathematical Functions in Python - Special Functions and Constants
In this article, we will learn about special functions and constants available in the math module in the Python Standard Library.Here we will discuss some constants like −pieinfNantauAnd some functions likeGammaIsinfIsnanisfinite()erf()Let's discuss constants and their respective values −pi3.141592…..e2.718281…...inf6.283185…...nantauNow let’s discuss some special functions and their implementation −Gamma − return the value of gamma(n)Isinf − checks whether the value of the function is infinity or not.Isnan − check whether the return value is a number or not.Isfinite − return True if the value is neither an infinity or a nan false otherwiseErf − returns the error function of x.Now let;’s take ...
Read MorePrint system time in C++ (3 different ways)
There are different ways by which system day, date and time can be printed in Human Readable Form.First wayUsing time() − It is used to find the current calendar time and have arithmetic data type that store timelocaltime() − It is used to fill the structure with date and timeasctime() − It converts Local time into Human Readable FormatDay Month Date hour:month:second YearExample#include #include // used to work with date and time using namespace std; int main() { time_t t; // t passed as argument in function time() struct tm * tt; // decalring variable for localtime() ...
Read MoreList Methods in Python - in, not in, len(), min(), max()
In this article, we will learn about various types of list methods available to us in Python 3.x. Or earlier. These operators allow us to perform the basic operations on the list content.In & Not in operators“in” operator − This operator is used to check whether an element is present in the passed list or not. Returns true if the element is present in the list otherwise returns false.“not in” operator − This operator is used to check whether an element is not present in the passed list or not. Returns true if the element is not present in the ...
Read MoreIterate over a dictionary in Python
In this article, we will learn about iteration/traversal of a dictionary in Python 3.x. Or earlier.A dictionary is an unordered sequence of key-value pairs. Indices can be of any immutable type and are called keys. This is also specified within curly braces.Method 1 − Using iterables directlyExampledict_inp = {'t':'u', 't':'o', 'r':'i', 'a':'l', 's':'p', 'o':'i', 'n':'t'} # Iterate over the string for value in dict_inp: print(value, end='')OutputtrasonMethod 2 − Using iterables for values of the dictionaryExampledict_inp = {'t':'u', 't':'o', 'r':'i', 'a':'l', 's':'p', 'o':'i', 'n':'t'} # Iterate over the string for value in dict_inp.values(): print(value, end='')OutputoilpitMethod 3 − ...
Read MoreMeasure execution time of small Python code snippets (timeit)
The Timer class and other convenience functions in timeit module of Python's standard library are designed to provide a mechanism to measure time taken by small bits of Python code to execute. The module has a command line interface and the functions can be called from within program as well.Easiest way to measure time of execution is by using following convenience functiontimeit()This function returns object of Timer class. It mainly requires two parameters.stmt − a string containing valid Python statement whose execution time is to be measured.setup − a string containing Python statement which will be executed once, primarily to ...
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