## How do I filter a row by value in R?

In this tutorial, we introduce how to filter a data frame rows using the dplyr package:

- Filter rows by logical criteria: my_data %>% filter(Sepal.
- Select n random rows: my_data %>% sample_n(10)
- Select a random fraction of rows: my_data %>% sample_frac(10)
- Select top n rows by values: my_data %>% top_n(10, Sepal.

**How do I select a row from a matrix in R?**

Similar to vectors, you can use the square brackets [ ] to select one or multiple elements from a matrix. Whereas vectors have one dimension, matrices have two dimensions. You should therefore use a comma to separate the rows you want to select from the columns.

### How do you get a column from a matrix in R?

R – Get Specific Column of Matrix To get a specific column of a matrix, specify the column number preceded by a comma, in square brackets, after the matrix variable name. This expression returns the required row as a vector.

**How do I select a column based on condition in R?**

Select Data Frame Columns in R

- pull(): Extract column values as a vector.
- select(): Extract one or multiple columns as a data table.
- select_if(): Select columns based on a particular condition.
- Helper functions – starts_with(), ends_with(), contains(), matches(), one_of(): Select columns/variables based on their names.

#### How do I select a column with condition in R?

**How do I filter all columns in R?**

Filtering across multiple columns

- filter_all() will filter all columns based on your further instructions.
- filter_if() requires a function that returns a boolean to indicate which columns to filter on.
- filter_at() requires you to specify columns inside a vars() argument for which the filtering will be done.

## How do I filter multiple values in a column in R?

In this, first, pass your dataframe object to the filter function, then in the condition parameter write the column name in which you want to filter multiple values then put the %in% operator, and then pass a vector containing all the string values which you want in the result.

**How do I add a column to a matrix in R?**

Adding Column To A Matrix For adding a column to a Matrix in we use cbind() function. To know more about cbind() function simply type? cbind() or help(cbind) in R. It will display documentation of cbind() function in R documentation as shown below.

### How do I remove a column from a matrix in R?

Just use the command S <- S[,-2] to remove the second column. Similarly to delete a row, for example, to delete the second row use S <- S[-2,] .

**How to filter a single column of a matrix in R?**

To filter a single column of a matrix in R if the matrix has column names, we can simply use single square brackets but this will result in a vector without the column name. If we want to use the column name then column name or column number needs to be passed with drop=FALSE argument as shown in the below examples.

#### How to use filter() method in R?

The filter () method in R can be applied to both grouped and ungrouped data. The expressions include comparison operators (==, >, >=), logical operators (&, |, !, xor ()), range operators (between (), near ()) as well as NA value check against the column values. The subset dataframe has to be retained in a separate variable.

**How do I select the last 3 columns in a matrix?**

The following command will select the first row of the matrix above. And this will select the last three. The result will be a matrix in both cases. If you want to use column names to select columns then you would be best off converting it to a dataframe with Or, you could use the subset command. Show activity on this post.

## How to filter by multiple values with multiple conditions in R?

Generally when filtering by single variable and having multiple conditions will involve the “or” operator. Going forward you will see how the variety of filter operator combinations in R can change when we look at filtering by multiple values with single or multiple conditions.

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