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R Programming Articles
Page 25 of 174
How to find the proportion of each value for a cross tab obtained from a data frame in R?
To find the proportion of each value for a cross tab obtained from a data frame, we can use prop.table function. Suppose we have a data frame called df that contains three columns, two categorical say C1 and C2 and one numerical say Y then the cross tab will be created by using the command xtabs(Y~.,df). Now the proportion of each value can be found by using prop.table(xtabs(Y~.,df),1).Example1Consider the below data frame −f1
Read MoreHow to create data frame using nested list elements in R?
To create data frame using nested list elements, we would need to unlist the list elements and store them in a matrix then read as a data frame using data.frame function. For example, if we have a nested called LIST then the data frame can be created by using the command −data.frame(matrix(unlist(LIST),ncol=”No of columns we want”,byrow=F))Check out the below example to understand how it works.ExamplenestedList
Read MoreHow to deal with Error: stat_count() can only have an x or y aesthetic in R?
To deal with Error: stat_count() can only have an x or y aesthetic, we need to pass the stat="identity" argument inside geom_bar function. Since we do not pass the count for bars and a bar graph can only contain only count variable, hence stat="identity" is needed so that geom_bar considers only one variable in aes for counting. Check out the below example to understand the difference.ExampleConsider the below data frame −factor
Read MoreHow to check if a time series is stationary in R?
To check if a time series is stationary, we can use Dickey-Fuller test using adf.test function of tseries package. For example, if we have a time series object say TimeData then to check whether this time series is stationary or not we can use the command adf.test(TimeData).Example1x1
Read MoreHow to apply multiple AND conditions to a data frame in R?
To apply multiple conditions to a data frame, we can use double and sign that is &&. For example, if we have a data frame called df that contains three columns say x, y, z and we want to add a value to all columns if first element in z equals to 5 then it can be done by using the command −if(df$x && df$y && df$y == 5){ df$x = df$x+10 df$y = df$y+10 df$z = df$z+10 }Example1Consider the below data frame −x1
Read MoreHow to create multiple bar plots for varying categories with same width bars using ggplot2 in R?
To create multiple bar plots for varying categories with same width bars using ggplot2, we would need to play with width argument inside geom_bar function to match the width of the bars in each bar plot. The best way to do this would be setting the larger ones to 0.25 and the shorter ones to 0.50.ExampleConsider the below data frame −x1
Read MoreHow to find the high leverage values for a regression model in R?
To find the high leverage values for a regression model, we first need to find the predicted values or hat values that can be found by using hatvalues function and then define the condition for high leverage and extract them. For example if we have a regression model say M then the hat values can be found by using the command hatvalues(M), now to find the high leverage values that are greater than 0.05 can be found by using the below code −which(hatvalues(M)>0.05)Example1Consider the below data frame −x1
Read MoreHow to add a variable description in R?
To add a variable description in R, we can use comment function and if we want to have a look at the description then structure call of the data frame will be used. For example, if we have a data frame say df that contains a column x then we can describe x by using the command comment(df$x)
Read MoreHow to randomly sample rows from an R data frame using sample_n?
To randomly sample rows from an R data frame using sample_n, we can directly pass the sample size inside sample_n function of dplyr package. For example, if we have data frame called df then to create a random sample of 5 rows in df can be done by using the command −df%>%sample_n(5)Example1Consider the below data frame −x1
Read MoreHow to convert a list to JSON in R?
To convert a list to JSON, we can use toJSON function of jsonlite package. For example, if we have a list called LIST then it can be converted to a JSON by using the command toJSON(LIST,pretty=TRUE,auto_unbox=TRUE). We need to make sure that the package jsonlite is loaded in R environment otherwise the command won’t work.ExampleList
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