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Articles by Nizamuddin Siddiqui
Page 67 of 196
How to find the frequency vector elements that exists in another vector in R?
If a vector value exists in another vector then we might want to find the frequency/count for such values in the other vector. For example, if we have two vectors say x and y, and some of the values in y exists in x as well. Therefore, we can find the frequency of values in x for y values can be found by using the command colSums(outer(x,y,"==")).Examplex1
Read MoreHow to create a subset using character column with multiple matches in R?
Subsetting is one of the most important aspects of data analysis. One such situation could be subsetting the character column based on multiple values. For example, if a character column of an R data frame has 5 categories then we might want to extract only 2 or 3 or 4 values then it can be done by using the filter function of dplyr package with str_detect function of stringr package.Consider the below data frame −ExampleGroup
Read MoreHow to create a single data frame from data frames stored in a list with row names in R?
If we have multiples data frames of same size stored in a list and we believe that these data frames have similar characteristic then we can create a single data frame. This can be done with the help of do.call. For example, if we have a list defined with the name List containing data frames with equal number of rows with their names then a single data frame can be created do.call(rbind,unname(List)).Exampledf1
Read MoreHow to collapse data frame rows in R by summing using dplyr?
To collapse data frame rows by summing using dplyr package, we can use summarise_all function of dplyr package. For example, if we have a data frame called df that has a categorical column say Group and one numerical column then collapsing of rows by summing can be done by using the command −df%>%group_by(Group)%>%summarise_all(funs(sum))Consider the below data frame −ExampleGroup
Read MoreHow to change the legend shape using ggplot2 in R?
By default, the shape of legend is circular but we can change it by using the guides function of ggplot2 package. For example, if we have a data frame with two numerical columns say x and y, and one categorical column Group then the scatterplot between x and y for different color values of categories in categorical column Group having different shape of legends can be created by using the below command −ggplot(df, aes(x, y, color=Group))+geom_point()+guides(colour=guide_legend(override.aes=list(shape=0)))Here, we can change the shape argument value to any value between starting from 0 to 25.Consider the below data frame −Examplex
Read MoreHow to convert columns of an R data frame into a single vector?
Sometimes all the columns in a data frame have similar data characteristics representing a particular variable. For example, having a data frame containing five columns each with heights of people. To convert this type of data frame into a vector we can use as.vector function along with the as.matrix function. The as.matrix will read the data frame columns so that the array of values can be created.Example1y1
Read MoreHow to select positive values in an R data frame column?
We know that positive values are greater thandf1$x[which(df1$x>0)]Example1set.seed(254) x
Read MoreHow to save a plot in pdf in R?
To save a plot in pdf, we can use the pdf function in base R. For example, if we want to save a plot with the name PDF then it can be done using the below command −pdf("PDF.pdf")After this we can create the plot and use dev.off().Examplepdf("pdfExample.pdf") plot(1:10)OutputExampledev.off()OutputTo check where it is saved, find the working directory using getwd().
Read MoreHow to create the stacked bar plot using ggplot2 in R with labels on the plot?
The creation of stacked bar plot using ggplot2 can be done with the help of position="stack" argument inside geom_bar function. If we want to create the stacked bar plot then geom_text function will be used with the same position argument and the aes to define the labels as shown in the below example.Exampledf
Read MoreHow to find the extremes of a data frame column in R if infinity exists in the column?
To find the extremes of a data frame column that is numeric can be done with the help of min and max function but if we want to get the same in single line code then range function can be used. If there are some infinity values in the column then range.default function will be used as shown in the below example.Exampley1
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