Server Side Programming Articles - Page 1446 of 2650

To convert a date or date vector to POSIXct, we can use as.POSIXct function but we also need to pass the appropriate date format inside the function. For example, if we have a date "2020-11-14" then it can be converted to POSIXct by using as.POSIXct("2020-11-14", format="%Y-%m-%d").Example1Live Demo> date1 as.POSIXct(date1, format="%Y-%m-%d")Output[1] "2020-04-01 IST"Example2Live Demo> date2 date2Output[1] "2020-02-12" "2020-06-01" "2020-04-01" "2020-05-01" "2020-01-21" [6] "2020-01-21" "2020-06-01" "2020-04-27" "2020-05-11" "2020-06-01" [11] "2020-01-21" "2020-03-31" "2020-05-01" "2020-02-12" "2020-01-21" [16] "2020-05-01" "2020-03-31" "2020-04-01" "2020-05-01" "2020-01-21" [21] "2020-05-01" "2020-04-11" "2020-05-11" "2020-04-01" "2020-03-31" [26] "2020-04-11" "2020-04-01" "2020-03-31" "2020-04-01" "2020-04-11" [31] "2020-05-11" "2020-06-01" "2020-03-31" "2020-04-27" "2020-01-21" [36] "2020-01-21" "2020-04-01" "2020-06-01" ... Read More

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

If we have missing data in our data frame then some of them can be replaced if we have enough information about the characteristic of the case for which the information is missing. But if that information is not available and we do not find any suitable way to replace the missing values then complete.cases function can be used with the columns that has missing values.ExampleConsider the below data frame:Live Demo> set.seed(19991) > x1 x2 x3 x4 x5 df1 df1Output x1 x2 x3 ... Read More

Sometimes we want to created repeated values, this is helpful in different scenarios such as measuring an effect of a constant on multiple variables. The list values can be also replicated for similar purpose of analysis. The replication of list of a list can be created by using rep function. For example, if we have a list called x and we want to create five times replicated list of this list then we can use the code rep(list(x), 5).Example1Live Demo> List1 List1Output$x1 [1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 ... Read More

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 More

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:

The two most easy ways to create an empty plot using ggplot2 are using geom_blank function and also adding the theme_bw along with the geom_blank. The geom_blank will create an empty plot with white gridlines and grey background, on the other hand, addition of theme_bw will create the empty plot with grey gridlines and white background.ExampleConsider the below data frame:Live Demo> set.seed(151) > x y df dfOutput      x         y 1  -0.05153895 0.3139643 2   0.76573738 0.1816184 3  -0.14673959 0.8201743 4  -0.11318581 1.6005576 5  -0.39551140 0.6770630 6  0.78227595 0.7446956 7  -1.39747811 0.7004385 8  -1.01883832 1.2728014 ... Read More

The Kruskal-Wallis test is the non-parametric analogue of one-way analysis of variance. The non-parametric tests are used in situations when the assumptions of parametric tests are not met. If we find significant difference in Kruskal-Wallis then post hoc tests are done to find where the difference exists. For this purpose, we can perform dunn test. The function of dunn test can be accessed through FSA package.Example1Loading FSA package:> library(FSA)Consider the below data frame:Live Demo> x1 y1 df1 df1Output  x1 y1 1 E 1.1191117 2 D 1.1276032 3 D 1.5610692 4 E 1.1585054 5 E 1.0239322 6 C ... Read More

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

The list elements of two lists cannot be added directly but we can do this addition by unlisting the elements. To do this, we would need to use lapply function. For example, if we have two lists defined as x and y then the sum of the elements in these lists can be calculated as follows:Examplelapply(seq_along(x), function(i) unlist(x[i])+unlist(y[i]))Example1Live Demo> x1 x1Output[[1]] [1] 0 3 0 1 2 0 1 0 1 3 3 0 0 0 1 1 0 1 0 1 1 0 2 0 0 6 1 2 1 1 1 1 2 1 1 0 0 [38] ... Read More