What Does NCOL Mean In R?

What is Apply function in R?

Apply functions are a family of functions in base R which allow you to repetitively perform an action on multiple chunks of data.

An apply function is essentially a loop, but run faster than loops and often require less code..

How do you number rows in R?

To Generate Row number to the dataframe in R we will be using seq.int() function. Seq.int() function along with nrow() is used to generate row number to the dataframe in R. We can also use row_number() function to generate row index.

What is mutate in R?

In R programming, the mutate function is used to create a new variable from a data set. In order to use the function, we need to install the dplyr package, which is an add-on to R that includes a host of cool functions for selecting, filtering, grouping, and arranging data.

What does Names do in R?

names is a generic accessor function to the names attribute of an R object, typically a vector . The first form prints the names of the observations and the second sets the names. In this case, value must be a vector of character strings of the same length as x .

What does NROW mean in R?

The nrow R function returns the number of rows that are present in a data frame or matrix. Above, you can find the R code for the usage of nrow in R.

What does data frame do in R?

Data Frames The function data. frame() creates data frames, tightly coupled collections of variables which share many of the properties of matrices and of lists, used as the fundamental data structure by most of R’s modeling software.

What is difference between Lapply and Sapply?

If the programmers want the output to be a data frame or a vector, then sapply function is used whereas if a programmer wants the output to be a list then lapply is used. There is one more function known as vapply which is preferred over sapply, as vapply allows the programmer to specify the output type.

How do I view a dataset in R?

Here is how to locate the data set and load it into R. Command library loads the package MASS (for Modern Applied Statistics with S) into memory. Command data() will list all the datasets in loaded packages. The command data(phones) will load the data set phones into memory.

What does str () mean in R?

str does not stand for string, it stands for structure: str(…) displays the internal structure of a given R object.

How do you subset in R?

So, to recap, here are 5 ways we can subset a data frame in R:Subset using brackets by extracting the rows and columns we want.Subset using brackets by omitting the rows and columns we don’t want.Subset using brackets in combination with the which() function and the %in% operator.Subset using the subset() function.More items…•

Is apply faster than for loop R?

The apply functions (apply, sapply, lapply etc.) are marginally faster than a regular for loop, but still do their looping in R, rather than dropping down to the lower level of C code. … Essentially, this means calling a function that runs its loops in C rather than R code.

What is Mapply?

mapply is a multivariate version of sapply . mapply applies FUN to the first elements of each … argument, the second elements, the third elements, and so on. Arguments are recycled if necessary.

What is factor R?

Conceptually, factors are variables in R which take on a limited number of different values; such variables are often refered to as categorical variables. Factors in R are stored as a vector of integer values with a corresponding set of character values to use when the factor is displayed. …

How do you edit data in R?

Entering and editing data by hand In the R Commander, you can click the Data set button to select a data set, and then click the Edit data set button.

What does head () do in R?

Returns the first or last parts of a vector, matrix, table, data frame or function. Since head() and tail() are generic functions, they may also have been extended to other classes.