Server Side Programming Articles - Page 1622 of 2646

In general, the line chart is drawn to view the trend of something and we might also have some threshold point for that trend, for example, if blood pressure is plotted then we might want to show 60 mm Hg as well because this is the lowest acceptable value for blood pressure recommended by doctors. Therefore, it can be plotted as a vertical line if we want to plot blood pressures of a person. Similarly, there can be many situations where we can use a vertical line to visualize the threshold value. This can be achieved in ggplot2 with the ... Read More

If all the columns in an R data frame are numeric then it makes sense to find the mean for each of the columns. This calculation will help us to view how different the values of means are for each of the columns but to make sure that they are significantly different, we will need to run a hypothesis test. To find the column means of a data frame or a matrix we can use colMeans function.ExampleConsider the below data frame − Live Demoset.seed(9) x1

The analysis of variance technique helps us to identify whether there exists a significant mean difference in more than two variables or not. To detect this difference, we either use F-statistic value or p-value. If the F-statistic value is greater than the critical value of F or if p-value is less than the level of significance then we say that at least one of the means is significantly different from the rest. To extract the p-value and F-statistic value, we can make use of summary function of the ANOVA model.Example Live Demoset.seed(123) Group

Sometimes the levels of a factor are not correctly recorded, for example, recording male with M in some places and with Mal in some places hence there are two levels for level male. Therefore, the number of levels increases if the factor levels are incorrectly recorded and we need to fix this issue because the analysis using these factor levels will be wrong. To convert the incorrect factor levels into the appropriate ones, we can use list function to define those levels.Example 1 Live DemoF

If two columns are of a form such that one column contains the name of the vector values and another column having the values of a vector then we might want to convert them into a vector. To do this, we can simply read the vectors with their data type and structure them with structure function.Example 1 Live Demox1

When we use aggregate function to find maximum or any other value, the output of the aggregation does not provide all the columns that corresponds to the maximum value. Therefore, we need to merge the data frame obtained by using aggregate with the original data frame. In this way, we will get only those rows that are common between the new data frame and the original one.ExampleConsider the below data frame − Live Demoset.seed(99) x1

A point chart is usually drawn to see the relationship between two continuous variables and it is also called scatterplot but if the independent variable is categorical then we simply call it a point chart. Often, we want to join or connect the points of a point chart to visually represent the variation of categories of the independent variable and make it a line chart. This can be done by setting stat_summary argument geom to line and setting group = 1 in aes.ExampleConsider the below data frame − Live DemoClass

The value NULL is used to represent an object especially a list of length zero. If a list contains NULL then we might want to replace it with another value or remove it from the list if we do not have any replacement for it. To remove the NULL value from a list, we can use the negation of sapply with is.NULL.Examples Live Demox

In our daily life, we might want to know what was the date before some number of days. This is also required in professional life, especially in those professions where we work on projects and have tight deadlines. To find the date before a certain number of days we can just use subtraction sign after reading the date with as.Date.Examplesas.Date("2001-01-01")-30 [1] "2000-12-02" as.Date("2020-06-30")-30 [1] "2020-05-31" as.Date("2020-06-30")-50 [1] "2020-05-11" as.Date("2020-06-30")-100 [1] "2020-03-22" as.Date("2020-06-30")-120 [1] "2020-03-02" as.Date("2020-06-30")-15 [1] "2020-06-15" as.Date("2020-06-30")-45 [1] "2020-05-16" as.Date("2020-06-30")-40 [1] "2020-05-21" as.Date("2020-12-25")-20 [1] "2020-12-05" as.Date("2020-12-25")-300 [1] "2020-02-29" as.Date("2020-12-25")-125 [1] "2020-08-22" as.Date("2020-12-25")-80 [1] "2020-10-06"We can also use / to ... Read More

The permutation is the combination with orders. For example, if we want to create a key for lock with a sequence of numbers then it must be order in some direction, otherwise, it will be difficult to remember and easy to unlock. We can find the permutation of some numbers or characters by using permn function of combinat package.Loading the combinat package −library(combinat)Examples that create list of permutations −permn(LETTERS[1:4]) [[1]] [1] "A" "B" "C" "D" [[2]] [1] "A" "B" "D" "C" [[3]] [1] "A" "D" "B" "C" [[4]] [1] "D" "A" "B" "C" [[5]] [1] "D" "A" "C" "B" [[6]] ... Read More