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Articles by Nizamuddin Siddiqui
Page 47 of 196
How to minus one column from another in an R matrix?
To minus one column from another in an R matrix, we first need to read the matrix as a data frame using as.data.frame then find minus the columns using minus sign and accessing the column of the data frame. To understand how it can be done look at the steps in below examples.ExampleConsider the below data frame −M1
Read MoreHow to convert negative values in a matrix to 0 in R?
To convert negative values in a matrix to 0, we can use pmax function. For example, if we have a matrix called M that contains some negative and some positive and zero values then the negative values in M can be converted to 0 by using the command pmax(M,0).ExampleConsider the below data frame −M1
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 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 ...
Read MoreHow to get the colour name from colour code in R?
To get the color name from color code, we can use the color_id function of plotrix package. If we have a vector of colour codes say x then the colour name can be found by using the command sapply(x, color.id).Example> x xOutput[1] "#FF0000" "#FF1F00" "#FF3D00" "#FF5C00" "#FF7A00" "#FF9900" "#FFB800" [8] "#FFD600" "#FFF500" "#EBFF00" "#CCFF00" "#ADFF00" "#8FFF00" "#70FF00" [15] "#52FF00" "#33FF00" "#14FF00" "#00FF0A" "#00FF29" "#00FF47" "#00FF66" [22] "#00FF85" "#00FFA3" "#00FFC2" "#00FFE0" "#00FFFF" "#00E0FF" "#00C2FF" [29] "#00A3FF" "#0085FF" "#0066FF" "#0047FF" "#0029FF" "#000AFF" "#1400FF" [36] "#3300FF" "#5200FF" "#7000FF" "#8F00FF" "#AD00FF" "#CC00FF" "#EB00FF" [43] "#FF00F5" "#FF00D6" "#FF00B8" "#FF0099" "#FF007A" "#FF005C" "#FF003D" [50] "#FF001F"Loading plotrix ...
Read MoreHow to find the significant correlation in an R data frame?
To find the significant correlation in an R data frame, we would need to find the matrix of p-values for the correlation test. This can be done by using the function rcorr of Hmisc package and read the output as matrix. For example, if we have a data frame called df then the correlation matrix with p-values can be found by using rcorr(as.matrix(df)).Example1Consider the below data frame −> x1 x2 x3 df1 df1Output x1 x2 x3 1 -0.96730523 -1.73067540 -0.01974065 2 0.08564529 -0.05200856 0.76356487 3 -0.33694783 ...
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 change row values based on column values in an R data frame?
Changing row values based on column values means that we want to change the row values for a particular column if the column values satisfy a certain condition. For example, if we have a data frame called df that contains a column say x and we want to set all the values in x to 5 if they are greater than 5 then it can be done as df[df$x>5, ] x1 x2 df1 df1Output x1 x2 1 3 10 2 3 3 3 1 8 4 2 4 5 1 7 6 1 4 ...
Read MoreHow to create boxplot of vectors having different lengths in R?
If we have multiple vectors of different lengths then the boxplot for such vectors can be created by creating a single data frame using those vectors with a categorical column showing the name of the vectors and a numerical column having the corresponding values. Then boxplot function will be used as shown in the below example.ExampleConsider the below vector x and y and create the data frame using them −> x y df dfOutput X Grp 1 4 x 2 2 x 3 1 x 4 2 x 5 0 x 6 2 x ...
Read MoreHow to sort a vector in R based on manual position of elements?
To sort a vector based on manual position of elements, we can use order function along with the factor function. The factor function will help us to arrange the vector elements in the order we want by defining the levels as vector elements and order function will order them. Check out the below examples to understand how it works.Example1> x1 x1Output[1] 0 1 0 0 1 2 1 2 3 1 2 2 2 4 3 1 4 1 0 1 1 3 3 0 0 4 4 2 4 2 4 2 0 4 0 1 1 [38] 4 ...
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