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Articles by Nizamuddin Siddiqui
Page 90 of 196
How to find the column number of minimum values in each row for a data frame in R?
To find the column number of minimum values in each row for a data frame, we can use apply function but if we want to return the output in tabular form then matrix function should be used. For example, if we have a data frame df then our problem can be solved by using the code: as.matrix(apply(df, 1, which.min)).ExampleConsider the below data frame:> set.seed(37) > x1 x2 x3 x4 x5 df1 df1Outputx1 x2 x3 x4 x5 1 1 2 4 9 3 2 0 5 8 10 4 3 1 3 8 6 1 4 1 5 5 8 1 ...
Read MoreHow to find the sum of corresponding elements in multiple vectors even if they contain NA's in R?
If we have multiple vectors then the sum of the corresponding elements can be found by using rowSums functions and the vectors can be combined by using cbind so that R can easily read the corresponding elements. But if there are NA values in one or more vectors then we also need to add na.rm=TRUE argument.Exampleset.seed(100) x1
Read MoreHow to find the rank of a matrix in R?
The rank of a matrix is defined as the maximum number of linearly independent vectors in rows or columns. If we have a matrix with dimensions R x C, having R number of rows and C number of columns, and if R is less than C then the rank of the matrix would be R. To find the rank of a matrix in R, we can use rankMatrix function in Matrix package.Loading Matrix package −library(Matrix)ExampleM1
Read MoreHow to check whether a data frame exists or not in R?
Sometimes we keep writing codes in the programming console and suddenly we need to use something that was used in the upper side of programming console then recalling it becomes a little ambiguous if we forget about it. In this case, we might want to check whether something exists or not and that something could be a data frame in R programming. For this purpose, we can use the below syntax −Syntaxexists("data_frame_name")&&is.data.frame(get("data_frame_name "))Consider the below data frame −Exampleset.seed(101) x1
Read MoreHow to create a subset based on levels of a character column in R?
In R programming, mostly the columns with string values can be either represented by character data type or factor data type. For example, if we have a column Group with four unique values as A, B, C, and D then it can be of character or factor with four levels. If we want to take the subset of these columns then subset function can be used. Check out the example below.Consider the below data frame −Exampleset.seed(888) Grp
Read MoreHow to visualize two categorical variables together in R?
The categorical variables can be easily visualized with the help of mosaic plot. In a mosaic plot, we can have one or more categorical variables and the plot is created based on the frequency of each category in the variables. To create a mosaic plot in base R, we can use mosaicplot function. The categories that have higher frequencies are displayed by a bigger size box and the categories that have less frequency are displayed by smaller size box.Consider the below data frame −Examplex1
Read MoreHow to set a level of a factor column in an R data frame to NA?
In data analysis, we often face inappropriate data and hence the data analysis becomes difficult. An example of inappropriate data is reading missing values with a different value by naming them as Missing or Not Available. It can be done by using below syntax −Syntaxlevels(“data_frame_name”$”Column_name”)[levels(“data_frame_name”$”Column_name”=="Missing"]
Read MoreHow to plot values with log scales on x and y axis or on a single axis in R?
We can plot numerical values in R with many scales and that includes log scale as well. Also, it is possible to plot the values with log scales on both the axes. In base R, the best way to do this is defining the axes values with decimal representation as shown in the below examples with well-defined log.Consider the below vector −Exampleset.seed(555) x
Read MoreHow to repeat a column of a data frame and join it with another data frame in R by rows?
Suppose we have a data frame df1 that contains 5 columns and another data frame df2 that contains only column but the data type of the columns in both the data frames is same. Now we might want to add the column of the second data frame starting at the end of the rows of the first data frame by creating the same number of columns as in first data frame. This might be required by researchers to understand the impact of an external variable on the result of the analysis and it can be done with the help of ...
Read MoreHow to find the position of one or more values in a vector into another vector that contains same values in R?
Finding the position of one of more values that are common in two vectors can be easily done with the help of match function. The match function will match the values in first and second vector then return the index or position of these common values in second vector.Exampleset.seed(145) x1
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