Nizamuddin Siddiqui has Published 2307 Articles

How to create random sample based on group columns of a data.table in R?

Nizamuddin Siddiqui

Nizamuddin Siddiqui

Updated on 08-Sep-2020 13:38:21

753 Views

Random sampling helps us to reduce the biasedness in the analysis. If we have data in groups then we might want to find a random sample based on groups. For example, if we have a data frame with a group variable and each group contains ten values then we might ... Read More

How to subset unique values from a list in R?

Nizamuddin Siddiqui

Nizamuddin Siddiqui

Updated on 08-Sep-2020 13:29:48

328 Views

We know that a list in R can have multiple elements of different data types but they can be the same as well. Whether we have the same type of elements or different ones, we might want to subset the list with unique values, especially in situations where we believe ... Read More

How to use shapiro wilk test to check normality of an R data frame column?

Nizamuddin Siddiqui

Nizamuddin Siddiqui

Updated on 08-Sep-2020 13:26:26

529 Views

To apply shapiro wilk test for normality on vectors, we just simply name the vector inside shapiro.test function but if we want to do the same for an R data frame column then the column will have to specify the column in a proper way. For example, if the data ... Read More

How to find power of a matrix in R?

Nizamuddin Siddiqui

Nizamuddin Siddiqui

Updated on 08-Sep-2020 13:23:12

648 Views

The power of a matrix in R cannot be found directly because there is not function in base R for that. Therefore, for this purpose we can use %^% of expm package. Firstly, we will install the expm package then load it and use %^%. For example, suppose we have ... Read More

How to increase the size of points on a scatterplot if the points are drawn based on another sequence using ggplot2 in R?

Nizamuddin Siddiqui

Nizamuddin Siddiqui

Updated on 08-Sep-2020 13:04:56

474 Views

When we draw a scatterplot using ggplot2 with points based on a sequence of values then the size of the points might be very small for the small values. As a result, it becomes a little difficult to view the points. Therefore, we might want to increase the size of ... Read More

How to extract elements of a list that do not contain NULL in R?

Nizamuddin Siddiqui

Nizamuddin Siddiqui

Updated on 08-Sep-2020 13:01:20

489 Views

A list sometimes contains NULL elements along with other elements. Therefore, we might want to get rid of that NULL element so that we can use our list without any hustle. To do this, we can use lapply function with the following syntax −Syntax“List_name”[!unlist(lapply(“List_name”, is.null))]ExampleConsider the below list − Live Demox1Read More

How to subset one or more sub-elements of a list in R?

Nizamuddin Siddiqui

Nizamuddin Siddiqui

Updated on 08-Sep-2020 12:58:56

544 Views

A list contains different type of elements and each of the them can have varying elements. To subset these sub-elements we can use sapply function and use c to subset the number of corresponding sub-elements. For example, if we have a list that contains five elements and each of those ... Read More

How to create frequency table of data.table in R?

Nizamuddin Siddiqui

Nizamuddin Siddiqui

Updated on 08-Sep-2020 12:53:46

385 Views

If we have an data.table object or a data frame converted to a data.table and it has a factor column then we might want to create a frequency table that shows the number of values each factor has or the count of factor levels. This is a data summarization method ... Read More

How to convert the correlation matrix into a data frame with combination of variables and their correlations in R?

Nizamuddin Siddiqui

Nizamuddin Siddiqui

Updated on 08-Sep-2020 12:42:40

2K+ Views

The cor function in R helps us to find the correlation matrix from a data frame or a matrix but the output of it always a matrix as intended. We might want to convert that matrix into a data frame which consists of all combination of variables with their correlation ... Read More

How to find the difference between row values starting from bottom of an R data frame?

Nizamuddin Siddiqui

Nizamuddin Siddiqui

Updated on 08-Sep-2020 12:30:32

141 Views

If an R data frame contains all numerical columns and we want to find the difference between row values then we will lose first row of the data frame because that will not be subtracted from any row. This can be done by using head function and minus sign. It ... Read More

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