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R Programming Articles
Page 136 of 174
How to find the row means for each matrix stored in an R list?
To find the row mean of all matrices stored in an R list, we can use sapply function along with rowMeans function.For example, if we have a list called LIST that contains some matrices then the row means for each matrix can be found by using the following command −sapply(LIST,rowMeans)Check out the below example to understand how it works.ExampleFollowing snippet creates the matrices −M1
Read MoreHow to find the median of frequency data in R?
If we have frequency data then we first need to find the total data or complete data by repeating the values up to the frequency corresponding to each value after that we can apply median function on this complete data.For Example, if we have a data frame called df that contains two columns say X and Frequency then we can find the total data by using the following command −Total_data
Read MoreHow to find the sample size for t test in R?
To find the sample size for t test, we can use pwr.t.test function of pwr package, wherever we can pass the arguments for alternative hypothesis such as one-sided or two-sided, significance level, power of the test and difference for two samples.Check out the below examples to understand how it works.Example 1Consider the following code to find sample size for t test −library("pwr") pwr.t.test(power=0.80, d=1, sig.level=0.05, alternative="two.sided")OutputIf you execute the above given code, it generates the following Output for the two-sample t test power calculation − n = 16.71472 d = 1 sig.level = 0.05 power = 0.8 alternative ...
Read MoreHow to make duplicate factor levels unique in an R data frame?
The factor with duplicate levels represents grouping data but if we want to convert the grouping data into nominal data then duplicate values must be removed or converted into unique values. To make duplicate factor levels unique in an R data frame, we can use make.unique function.Check out the below Examples to understand how it works.Example 1Following snippet creates a sample data frame −Factor
Read MoreHow to divide each value in an R data frame by 100?
We sometimes need to perform mathematical operations on all values in the data set. One such operation could be dividing each value by 100.For example, if we have a data frame called df then we can divide each value in df by 100 by using the below command −df[,1:ncol(df)]/100ExampleFollowing snippet creates a sample data frame −x1
Read MoreHow to find the groupwise common value for a data.table object?
To find the groupwise common value for a data.table object, we can use Reduce function with intersect function.For example, if we have a data.table object called DT that contains a numerical column say Num and a categorical column say C where C exists at the first position then the groupwise common value can be found by using the command given below −Reduce(intersect,DT[,.(list(unique(Num))),C]$V1)ExampleConsider the below data.table object −Group
Read MoreFind the frequency of exclusive group combinations based on multiple categorical columns in R.
To find the frequency of exclusive group combinations in an R data frame, we can use count function of dplyr package along with ungroup function.For Example, if we have a data frame called df that contains four grouping columns say Grp1, Grp2, Grp3, and Grp4 then we can count the unique group combinations in df by using the below command −count(df,Grp1,Grp2,Grp3,Grp4)%%ungroup()Example 1Following snippet creates a sample data frame −Class1
Read MoreHow to display superscript for X-axis title in base R plot?
To display superscript for X-axis title in base R plot, we can use ^ sign inside mtext function before defining the plain text.For example, if we want to display X2 at position 5 on X-axis then it can be done by using the below command −mtext(expression(paste(plain("X")^plain("2"))), side=1, line=2, at=5, cex=1.2)ExampleConsider the following snippet −plot(1:10) OutputIf you execute the above given snippet, it generates the following Output −To display superscript for X-axis title in base R plot, add the following code to the above snippet −Exampleplot(1:10, xlab="")OutputIf you execute all the above given snippets as a single program, it generates the ...
Read MoreHow to change the order of independent variables for regression summary output in R?
To change the order of independent variables in regression Output, we can pass the variables in the sequence we want while creating the regression model.For example, if we want to have three independent variables and we want to display first at the last position then it can be done as follows −lm(DP1~ ind_var_3+ ind_var_2+ind_var_1,data=”data_frame_name”)ExampleFollowing snippet creates a sample dataframe −iv1
Read MoreHow to check matrix values equality with a vector values in R?
If we have a vector called V that contains five values and a matrix say M that contains five columns and we want to check whether first value in the vector is present in the first column of each row in the matrix and so on for each value in the vector then we can use the below command −t(t(M)==V)Example 1Consider the below matrix and vector −M1
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