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Articles on Trending Technologies
Technical articles with clear explanations and examples
How to extract columns having at least one non-duplicate in R?
To extract columns from an R data frame having at least one non-duplicate, we can use Filter function.For Example, if we have a data frame called df that contains some columns having duplicate values and columns that do not contains at least one non-duplicate then we can extract columns having at least one non-duplicate by using the below command −Filter(var,df)Example 1Following snippet creates a sample data frame −x1
Read MoreCreate bar plot for grouped data of two columns in base R.
To create bar plot for grouped data in base R, we can create the table for both the columns and then use beside argument of barplot function to create the bar plot. To differentiate between the bars, we need to set legend argument to TRUE as well. To understand how it can be done check out the below Example.ExampleFollowing snippet creates a sample data frame −G
Read MoreGet a matrix as Output if a condition for a single value is met in R.
If we want to check a condition and the Output based on that condition needs to be a matrix then we can use if else function in R.For Example, if we have a value say V = 5 and we want to get matrix M1 if V is equal to 5 and matrix M2 if V is not equal to 5 then we can use the below command −if (V == 5) M1 else M2ExampleFollowing snippet creates a sample matrices −M1
Read MoreWhat is Implementation of LR Parsing Tables?
LR Parsing Tables are a two-dimensional array in which each entry represents an Action or goto entry. A programming language grammar having a large number of productions has a large number of states or items, i.e., I0, I1 … … In.So, due to more states, more Actions & goto entries will be filled, which requires a lot of memory. So, a two-dimensional array is not sufficient to store so many action entries, because each entry requires at least 8 bits to encode.So, we have to use more efficient encoding than a two-dimensional array for encoding, Action & goto field.For example, ...
Read MoreConsider the ambiguous grammar.\\nE → E + E\\nE → E * E\\nE → (E)\\nE → id\\n(a) Construct LR (0) items for above grammar.\\n(b) Construct SLR parsing table for grammar.\\n(c) Parse the input string id + id * id.
Problem Statement Consider the ambiguous grammar.E → E + EE → E * EE → (E)E → id(a) Construct LR (0) items for above grammar.(b) Construct SLR parsing table for grammar.(c) Parse the input string id + id * id. SolutionStep1− Construct Augmented Grammar(0) E′ → S(1) E → E + E(2) E → E ∗ E(3) E → (E)(4) E → idStep2− Find closure & goto functions to construct LR (0) items.Closure (E′ → ∙ E) =Applying goto on I9∵ goto cannot be applied on I9, ...
Read MoreHow to create normal probability plot in R with confidence interval bands?
To create normal probability plot in R with confidence interval bands, we can use qqPlot function of QTLRel package. We simply need to pass the vector name that contains normal distribution values inside qqPlot function or directly introduce the vector inside the function as shown in the below given examples.Example 1Use the following code to create normal probability plot −library("QTLRel") qqPlot(rnorm(10))OutputIf you execute the above given snippet, it generates the following Output −Example 2Add the following code to the above snippet to create normal probability plot −qqPlot(rnorm(500)) OutputIf you execute the above given snippet, it generates the following Output −Example ...
Read MoreCreate a matrix for odd number of elements by filling the last element with NA in R.
We can find the total number of elements for a matrix with the help of prod and dim function as shown in the below Examples. To create a matrix for odd number of elements by filling the last element with NA, we can use byrow argument.For Example, if we have a vector called V that contains 19 elements then we can create a matrix called M having 20 elements NA as the last element by using the below command −M
Read MoreHow to create an ID column in R based on categories?
If we have a categorical column in an R data frame then it can be used to create an ID column where each category will have its own ID defined on the basis of categories in the categorical column.For this purpose, we would need to read the categorical column with as.factor and as.numeric function as shown in the below examples.Example 1Following snippet creates a sample data frame −Group
Read MoreRotate a matrix by 90 degree without using any extra space in C++
We are given a 2-D array that will be used to form a matrix pattern. The task is to rotate a matrix by 90 degrees in an anti-clockwise direction such that the first row becomes the first column, second row becomes second column and third becomes third column and the challenge is that we don’t have to use any extra space.Let us see various input output scenarios for this −Input −int arr[row_col_size][row_col_size] = { { 5, 1, 4}, { 9, 16, 12 }, { 2, 8, 9}}Output −Rotation of a matrix by 90 degree without using any extra space ...
Read MoreHow to create a scatterplot with larger distance between facets in R?
By default, the distance/space between facets created by using ggplot2 is very less and it becomes a little uneasy for viewers to separately read the facets. Therefore, to deal with this problem we can increase the space between facets and it can be done with the help of theme function as shown in the example below.ExampleFollowing snippet creates a sample data frame &miuns;x
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