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Server Side Programming Articles
Page 1158 of 2109
How to sort an R data frame column without losing row names?
When we sort a data frame column in R, the row names are lost but we might need them. Therefore, sorting without losing row names is required and it can be done with the help of order function. For example, if we have a data frame called df that has a column x then sorting of x without losing row names can be done by using the below command −df[order(df$x),,drop=FALSE]Consider the below data frame −Examplex1
Read MoreHow to extract first value from a list in R?
To extract first value from a list, we first need to access the element using double square brackets then the sub-element of each element will be accessed using single square brackets. For example, if we have a list called LIST containing five elements each having 10 elements then the first sub-element of the LIST will be selected by using LIST[[1]][1].ExampleList1
Read MoreHow to remove single quote from string column in an R data frame?
Sometimes column values in an R data frame have single quote associated with them and to perform the analysis we need to remove that quote. Therefore, to remove single quote from string column, we can use gsub function by defining the single quote and replacing it with blank(not space) as shown in the below examples.Consider the below data frame −Examplex1
Read MoreHow to sort matrix columns independently in increasing order in R?
To sort a matrix column independently in increasing order means that ordering each column of the data frame in increasing order, therefore, sorting of values in one column does not affect the sorting in other columns. This can be done with the help of apply function along with the sort function as shown in the below examples.ExampleM1
Read MoreHow to save an xtable file locally using R?
To save an xtable file locally, obviously we first need to create the xtable and then use the print function for saving the file. Therefore, we require xtable package loaded in R environment and the data set that we want to save as an xtable file. In the below example, we have used iris data in base R for this purpose. Take a look at the example to understand how it works.Loading xtable package −library(xtable)Considering iris data −Exampledata(iris) head(iris, 20)OutputSepal.Length Sepal.Width Petal.Length Petal.Width Species 1 5.1 3.5 1.4 ...
Read MoreHow to find the two factor interaction variables in an R data frame?
If we have a data frame called df that contains four columns say x, y, z, and a then the two factor interaction columns will be xy, xz, xa, yz, ya, za. To find how many two factor interaction variables can be created using data frame columns, we can make use of combn function as shown in the below examples.Consider the below data frame −Examplex1
Read MoreHow to convert a date to quarter and year in R?
Most of the times the date data is available only in date format and there is not information about the quarter of the year. The quarter of the year is required when we want compare the quarters or do some time series analysis. For the conversion of date into quarter and year can be done by using as.yearqtr function from zoo package as shown in the below examples.Examplelibrary(zoo) as.yearqtr("2021-01-19", format="%Y-%m-%d")Output[1] "2021 Q1"as.yearqtr("2021-04-19", format="%Y-%m-%d")[1] "2021 Q2"as.yearqtr(c("2021-04-19", "2020-05-24", "2020-11-09"), format="%Y-%m-%d")[1] "2021 Q2" "2020 Q2" "2020 Q4" Examplex1
Read MoreHow to extract the residuals and predicted values from linear model in R?
The residuals are the difference between actual values and the predicted values and the predicted values are the values predicted for the actual values by the linear model. To extract the residuals and predicted values from linear model, we need to use resid and predict function with the model object.Consider the below data frame −Examplex1
Read MoreHow to create a linear model with interaction term only in R?
To create a linear model with interaction term only, we can use the interaction variable while creating the model. For example, if we have a data frame called df that has two independent variables say V1 and V2 and one dependent variable Y then the linear model with interaction term only can be created as lm(Y~V1:V2,data=df).Consider the below data frame −Examplex1
Read MoreHow to find the groupwise number of positive and negative values in an R data frame?
To find the groupwise number of positive and negative values in an R data frame, we can use mutate function of dplyr package. For example, if we have a data frame called df with one categorical column x and one numerical column y then the number of positive and negative values for categorical column can be found by using the below command −df%>%group_by(x)%>%mutate(positive=sum(y>0),negative=sum(y
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