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Programming Articles
Page 2123 of 2547
How to find the row wise sum for n number of columns in R?
To find the row wise sum of n number of columns can be found by using the rowSums function along with subsetting of the columns with single square brackets.For example, if we have a data frame called df that contains five columns and we want to find the row sums for last three columns then we can use the following command −df$Sum_3
Read MoreHow to extract the maximum value from named vector in R?
To extract the maximum value from named vector in R, we can use which.max function.For example, if we have a vector called X which is a named vector then we can use the following command to find the maximum value in X.X[which.max(X)]Check out the below examples to understand how it works.Example 1Following snippet creates a vector −x1
Read MoreHow to reduce the space between Y-axis value and ticks using ggplot2 in R?
To reduce the space between axis value and ticks using ggplot2, we can use theme function of ggplot2 package with margin set to 0.For example, if we have a data frame called df that contains two columns say x and y then the scatterplot between x and y with reduced space between Y-axis value and ticks can be created by using the following command −ggplot(df,aes(x,y))+geom_point()+theme(axis.text.y=element_text(margin=margin(r=0)))ExampleFollowing snippet creates a sample data frame −x
Read MoreHow to display fraction in a plot title using ggplot2 in R?
To display fraction in a plot title using ggplot2 in R, we can use frac function inside ggtitle function of ggplot2 package. Generally, fraction is displayed as X/Y but frac function helps to create the fraction in over form.Check out the below example to understand how over form of fraction can be displayed in a plot title using ggplot2.ExampleFollowing snippet creates a sample data frame −x
Read MoreHow to find the sequence of correlation between variables in an R data frame or matrix?
To find the sequence of correlation between variables in an R data frame or matrix, we can use correlate and stretch function from corrr package.For example, if we have a data frame called df then we can find the sequence of correlation between variables in df by using the below given command −df%>% correlate() %>% stretch() %>% arrange(r)Example 1Following snippet creates a sample data frame −x1% + arrange(r) Correlation method: 'pearson' Missing treated using: 'pairwise.complete.obs' # A tibble: 25 x 3OutputIf you execute all the above given snippets as a single program, it generates the following output − ...
Read MoreHow to create a matrix with vectors as elements in R?
To create a matrix with vectors as elements in R, we can create arrays because an array contains matrices with vectors as elements.Check out the below given examples of arrays and vectors extracted by the arrays to understand how matrices stored in an array represent vectors as elements.Example 1Following snippet creates arrays consisting of matrices −Array
Read MoreHow to create a vertical line in a time series plot in base R?
To create a time series plot, we can use simply apply plot function on time series object and if we want to create a vertical line on that plot then abline function will be used with v argument.For example, if we have a time series object called T and we want to create a time series plot of T with vertical line at point 5 then we can use the below given command after creating the plot −abline(v=5)ExampleTo create a vertical line in a time series plot in base R, use the following code −x
Read MoreHow to convert matrices stored in a list into vectors in R?
A list may contain vectors, data frames, matrices, lists etc. If a list contains matrices and we want to convert those matrices into vectors then lapply function can be used along with as.vector function.For example, if we have a list called LIST that contains matrices then we can convert those matrices into data frames by using the below given command − lapply(LIST,function(x) as.vector(x))ExampleFollowing snippet creates the matrices −M1
Read MoreHow to create a column with ratio of two columns in R?
To create a new column with ratio of two columns in an R data frame, we can use division sign.For example, if we have a data frame called df that contains two columns say X and Y and we want to create a new column with ratio of X and Y then we can use the below given command −df$Ratio_X_Y
Read MoreHow to find the number of times a variable changes its sign in an R data frame column?
To find the number of times a variable changes its sign in an R data frame column, we can use sign function with diff and sum function.For example, if we have a data frame called df that contains a column say C then, we can find the number of times C changes its sign by using the following command −sum(diff(sign(df$C))!=0)Example 1Following snippet creates a sample data frame −x
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