Programming Articles - Page 1768 of 3363

Labelling of points on a scatterplot helps us to identify the pair of observations. For example, if we are plotting weight and height of people then we can label it with person’s name, therefore, we will be able to understand which pair of points belong to which person. This can be done by using text function after creating the scatterplot with plot function.Examplex

We can join vectors by columns using cbind and it does not matter whether these vectors are of same length or not. If the vectors are of same length then all the values of both the vectors are printed but if the length of these vectors are different then the values of the smaller vector gets repeated. But we might not want to repeat the values/elements of the smaller vector and it is possible by setting the length of the smaller vector to the length of larger vector, this will create NA values in the smaller at places where the ... Read More

Mostly, we merge the data frames by columns because column names are considered prominent in data sets but it is also possible to merge two data frames by using rows. Merging by rows is likely to result in more uncleaned data as compared to the merging by columns. This can be done with the help of merge function and its by argument.ExampleConsider the below data frames −df1

We often create subsets of data in R to perform calculations based on smaller objectives of a whole objective in data analysis projects. Sometimes this subsetting is conditional on strings instead of numeric values. We can also create a subset of data.table on the basis of substring of row values for a column by using grep function.ExampleConsider the below data.table object −x1

We can create multiple plots using par(mfrow) on a single plot window in R. It might be possible that all of these plots are different or same as well. Irrespective of the type of plots, we can give a common title to all the plots. This can be a situation where we want to show, say, scatterplots, and histograms of few variables but the object of our analysis is fixed. To write a common title between plots in the plot window we can use mtext and adjust the title position by changing line argument.Exampleset.seed(100) x1

Sometimes we want to extract a sub-string from a big string and that sub-string lies after a particular character. For example, a string could be “Learning.Computer.Science.is.not.difficult-Author” and we want to extract the word Author from it. This can be done with the help of gsub function.Examplesx1

We know that a factor variable has many levels but it might be possible that the factor levels we have are not in the form as needed. For example, if we want to have capital letters as a factor level but the original data has small letters of English alphabets. In this situation we can rename those factor levels by using mutate of dplyr package.ExampleConsider the below data frame −City

We know that a factor variable has many levels but it might be possible that the factor levels we have are not in the form as needed. For example, if we want to have capital letters as a factor level but the original data has small letters of English alphabets. In this situation we can convert those factor levels by using mutate of dplyr package.ExampleConsider the below data frame −x

Generally, when we add a new column to an existing R data frame that column is added at the end of the columns but we might need it at the front. This totally depends on our ease of use, familiarity with variables, and their need. We can add a new column at the front of an existing R data frame by using cbind function.ExampleConsider the below data frame −ID

A matrix has only numeric values and sometimes these values are either incorrectly entered or we might want to replace some of the values in a matrix based on some conditions. For example, if we have few fives in a matrix then we might want to replace all fives to an another number which is greater than 5 or less than 5.ExampleConsider the below matrix −set.seed(123) M