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R Programming Articles
Page 20 of 174
How to preserve data frame structure after applying a function in R?
When we apply a function using apply family, by default the output is not in the form of a data frame. If we want to preserve the original data frame structure then we need to set the application of the apply family by setting it to the original data frame with single brackets and no arguments as shown in the below examples.Example1Consider the below data frame −> df1 df1Output x1 x2 1 4 2 2 6 2 3 5 2 4 2 1 5 8 4 6 7 2 7 5 3 8 ...
Read MoreHow to convert a binary matrix to logical matrix in R?
A binary matrix contains values such as Yes or NO, 1 or 0, or any other two values that represents opposite mostly and the globally accepted logical values are FALSE and TRUE. Therefore, to convert a binary matrix to logical matrix, we can use ifelse function and convert the one category of binary variable to appropriate logical value and for the rest returns the left-out value. This is a very easy task in R, check out the below examples to understand how it can be done.Example1> M1 M1Output[, 1] [, 2] [1, ] "No" "Yes" [2, ] "No" "No" [3, ...
Read MoreHow to subset a data frame based on a vector values in R?
If we have a vector and a data frame, and the data frame has a column that contains the values similar as in the vector then we can create a subset of the data frame based on that vector. This can be done with the help of single square brackets and %in% operator. The %in% operator will help us to find the values in the data frame column that matches with the vector values. Check out the below examples to understand how it works.Example1Consider the below data frame df1 and vector v1 −> x1 x2 df1 df1Outputx1 x2 1 2 ...
Read MoreHow to find the unique rows in an R data frame?
A unique row in an R data frame means that all the elements in that row are not repeated with the same combination in the whole data frame. In simple words, we can say that if we have a data frame called df that contains 3 columns and 5 rows then all the values in a particular row are not repeated for any other row. The search of this type of rows might be required when we have a lot of duplicate rows in our data set. To do this, we can use group_by_all function of dplyr package as shown ...
Read MoreHow to find the row and column index of a character value in an R data frame?
To find the row and column index for a numerical value in an R data frame we use which function and if the value is character then the same function will be used but we need to pass the value appropriately. For example, if we have a data frame called df that contains a value say Data then we can find the row and column index of Data by using the command as which(df=="Data", arr.ind=TRUE).Example1Consider the below data frame −> x1 x2 df1 df1Output x1 x2 1 Female 5 2 Female 5 3 Female 6 4 Female 6 ...
Read MoreHow to change the legend title in ggplot2 in R?
In ggplot2, by default the legend title is the title of the grouping column of the data frame. If we want to change that title then scale_color_discrete function. For example, if we have a data frame called df that contains two numerical columns x and y and one grouping column say group then the scatterplot with a different legend title can be created by using the below command −ggplot(df, aes(x, y, color=group))+geom_point()+scale_color_discrete("Gender")ExampleConsider the below data frame −> x y grp df dfOutput x y grp 1 -2.27846496 0.8121008 Male ...
Read MoreHow to split month and year from 6-digit numbers in an R data frame column?
Sometimes we get data that is not in the form to proceed with the analysis and one such situation is dates stored in 6-digit numbers as 202105 that represents fifth month of year 2021 instead of date format as 2021/05. Therefore, we need to split the date and extract the month and year from the number. This can be done easily with the help of transform function as shown in the below examples.Example1Consider the below data frame −> Date Response1 df1 df1Output Date Response1 1 202103 0.946367628 2 202103 1.241718518 3 202101 -0.657920816 4 202103 -0.809622853 5 ...
Read MoreHow to create bar plot with log values using ggplot2 in R?
To create the bar plot using ggplot2, we simply need to use geom_bar function and if we want to have the log scale of y variable then it can be set with aes under geom_bar. For example, if we have a data frame called df that contains a categorical column x and a numerical column y then the bar plot with log of y can be created by using the below command −ggplot(df, aes(x, y))+geom_bar(stat="identity", aes(y=log(y)))ExampleConsider the below data frame −> x y df dfOutput x y 1 S1 53347 2 S2 84208 3 S3 12140 4 S4 ...
Read MoreHow to filter single column of a matrix with column name 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.Example1> M1 colnames(M1) M1Output V1 V2 V3 V4 [1, ] 0 0 1 0 [2, ] 1 1 1 1 [3, ] 0 0 0 0 [4, ] 0 1 1 0 [5, ] 1 1 1 1 ...
Read MoreHow to find the row sum for each column by row name in an R matrix?
To find the row sum for each column by row name, we can use rowsum function. For example, if we have a matrix called M then the row sums for each column with row names can be calculated by using the command rowsum(M, row.names(M)).Example1> M1 rownames(M1) colnames(M1) M1Output V1 V2 Male 3 6 Female 6 5 Female 7 3 Female 2 5 Female 5 3 Female 4 4 Female 1 4 Female 4 4 Female 7 5 Male 2 5 Female 5 5 Male 7 1 Female 5 6 Male 6 5 Female 3 ...
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