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R Programming Articles
Page 146 of 174
How to display star/asterisk sign (*) inside a base R plot?
To display characters inside a base R plot we can simply use text function with expression and if we want to display an asterisk then we need to put the asterisk within double quotes. For example, if we want to display three stars then only expression(paste("***"))) should be used. Check out the below examples to understand how it works.Example1> plot(1:10,type="n") > text(8,9,expression(paste(Sig.^"***")))OutputExample2> plot(1:10,type="n") > text(5,6,expression(paste(Less_Sig.^"**")))OutputExample3> plot(1:10,type="n") > text(2,3,expression(paste(Very_Less_Sig.^"**")))Output
Read MoreHow to make the axes widths in a plot wider than default in base R?
The axes widths are generally very thin in plots but we can make them wider. This will be useful if we want to highlight the axes labels for reasons such as getting attention of the viewer on axes labels etc. To increase the width of the axes in a base R plot, we can use axis function and set the lwd argument.Example> x hist(x) > axis(side=1,lwd=4)Output:Example> axis(side=2,lwd=4)Output:
Read MoreHow to remove border of bars from histogram in base R?
By default, a histogram drawn in base R has black color borders around bars. We might want to remove these black borders to make the histogram visually smooth. This can be done by using lty argument with the hist function. For example, if we have a vector x and we want to create a histogram of x without border of bars then we can use the argument as hist(x,lty="blank").Example> x hist(x)Output:Creating histogram of x without border of bars:Example> hist(x,lty="blank")Output:
Read MoreHow to create an S4 object in R?
To create an S4 object, we can use setClass function where we will pass the object name, column names, and the type of the data that will be stored in the columns. For example, if we want to create an S4 with name data and two numerical columns called by x and y then we can use setClass("data", representation(x1="numeric", x2="numeric")).Example1> setClass("data1", representation(x1="numeric", x2="numeric")) > data1 data1OutputAn object of class "data1" Slot "x1": [1] -0.586187627 0.853689097 -0.602612795 -2.194235741 -1.318522292 [6] -0.984882420 0.273584140 0.364691611 1.025472248 1.198547297 [11] -0.709282551 -0.001441127 -0.201348012 1.296811172 1.520093861 [16] 2.071031215 0.472877022 0.616211695 0.642165615 -0.122773000 Slot "x2": [1] ...
Read MoreHow to create a histogram with main title in the outer margin of plot window in base R?
The main title of a histogram in base R can be inserted by using title function and if we want to have it in the outer margin then outer argument must be set to TRUE. If the outer argument does not fulfil our requirement then we can use par function to adjust the outer margin area and create the histogram. Check out the below example to understand how it works.Example> x hist(x) > title('Normal Distribution',outer=TRUE)OutputExample> par(oma=c(0,0,2,0)) > hist(x) > title('Normal Distribution',outer=TRUE)Output
Read MoreHow to find the group-wise median in an R data.table object?
When the assumptions of parametric analysis are not satisfied then we move on to non-parametric analysis and non-parametric analysis often deals with the calculation of median because the data is not normally distributed. If we want to find the group-wise median and the data is stored in a data.table object then lapply function can be used as shown in the below examples.ExampleLoading data.table package:> library(data.table)Consider the below data.table object:Example> Group x1 x2 x3 x4 dt1 dt1OutputGroup x1 x2 x3 x4 1: B 0.515370827 6.174187 542.9350 50.28300 2: B 0.522858146 6.976872 510.5568 49.71331 3: A 1.055456751 3.192242 476.7693 48.88280 4: A ...
Read MoreHow to create a horizontal bar plot using barplot function in R?
To create a bar plot in base R, we can directly use barplot function but the table of frequencies should be passed inside this function. If we want to create the barplot in horizontal manner then horiz=TRUE argument must be added. For example, if we have a vector x that contains repeating values then the horizontal bar plot of x can be created by using barplot(table(x),horiz=TRUE).Example1> x barplot(table(x),horiz=TRUE)OutputExample2> y barplot(table(y),horiz=TRUE)OutputExample3> z barplot(table(z),horiz=TRUE)Output
Read MoreHow to create a subset of a data frame in R without using column names?
The subsetting of a data frame can be done by using column names as well as column number. Also, we can subset by subsequent as well as non-subsequent column numbers. For example, if we have a data frame df that contains column x, y, z then we can make a subset of x and z by using df[, c(1, 3)].ExampleConsider the below data frame:> set.seed(191) > x1 x2 x3 x4 df1 df1Output x1 x2 x3 ...
Read MoreHow to create a line that passes through specified points in an R plot?
To create a line that passes through specified points, we first need to create the plot then using plot function then xspline function can be used to join the points with straight lines. The xspline function is specifically designed to draw curves and hence it can be also used to join points in a plot as shown in the below examples.Example1> plot(rpois(10,5)) > xspline(c(4,3,1),c(7,5,2))Output:Example2> plot(rnorm(10)) > xspline(c(4,3,1),c(0.3,-0.5,-1.5))Output:
Read MoreHow to create two 3d plots at a time in R?
The rgl package is specifically designed to create real-time interactive 3D plots and we can create two 3d plots using plot3d function of this package. Also, these plots can be viewed in the R console at a single point of time with the help of open3d() function.ExampleLoading rgl package:Example> library(rgl) > x y z plot3d(x,y,z)OutputExample> open3d() wgl 12 > plot3d(x,y,z,col=rainbow(5))Output
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