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Articles by Nizamuddin Siddiqui
Page 104 of 196
How to find the maximum using aggregate and get the output with all the columns in R?
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 −set.seed(99) x1
Read MoreHow to convert two columns of an R data frame to a named vector?
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 1x1
Read MoreHow to collapse factor levels in an R data frame?
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 1F
Read MoreHow to extract the p-value and F-statistic from aov output in R?
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.Exampleset.seed(123) Group
Read MoreHow to create a line chart using ggplot2 with a vertical line in R?
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 MoreHow to check if two data frames same or not in R?
Two data frames can be same if the column names, row names and all the values in the data frame are exactly same. We might to check this for data frames that we expect to be same, for example, if we have two data sets each one of have same number of rows, same number of columns, same data type for each of the columns, and the data view shows that values are same then it is worth checking whether the complete data sets are same or not. To do this checking in R, we can use identical function.Examplesdf1
Read MoreHow to initialize a data frame with variable names in R?
There are many ways to initialize a data frame in R but initializing with matrix is the best among them because creating the data frame with matrix help us to avoid entering the wrong number of columns and the wrong number of rows. After initializing the matrix, we can simply use as.data.frame to convert the matrix into a data frame and that’s it.Examplesdf1
Read MoreHow to increase the width of the lines in the boxplot created by using ggplot2 in R?
When we create a boxplot using ggplot2, the default width of the lines in the boxplot is very thin and we might want to increase that width to make the visibility of the edges of the boxplot clearer. This will help viewers to understand the edges of the boxplot in just a single shot. We can do this by using lwd argument of geom_boxplot function of ggplto2 package.ExampleConsider the below data frame −> ID Count df head(df, 20)Output ID Count 1 S1 20 2 S2 14 3 S3 17 4 S4 30 5 S1 17 6 S2 23 7 S3 36 ...
Read MoreHow to deal with missing values to calculate correlation matrix in R?
Often the data frames and matrices in R, we get have missing values and if we want to find the correlation matrix for those data frames and matrices, we stuck. It happens with almost everyone in Data Analysis but we can solve that problem by using na.omit while using the cor function to calculate the correlation matrix. Check out the examples below for that.ExampleConsider the below data frame −> x1 x2 x3 x4 df head(df, 20)Output x1 x2 x3 x4 1 2 2.6347839 4 2.577690 2 3 0.3082031 1 6.250998 3 1 0.3082031 3 7.786711 4 1 ...
Read MoreHow to create cumulative sum chart with count on Y-axis in R using ggplot2?
Cumulative sums are often used to display the running totals of values and these sums also help us to identify the overall total. In this way, we can analyze the variation in the running totals over time. To create the cumulative sum chart with count on Y-axis we can use stat_bin function of ggplot2 package.ExampleConsider the below data frame −> x df head(df, 20)Output x 1 1.755900133 2 1.185746239 3 0.821489888 4 1.358420721 5 2.719636441 6 2.885153151 7 1.131452570 8 0.302981998 9 0.433865254 10 2.373338327 11 0.428436149 12 1.835789725 13 2.600838211 14 2.108302471 15 1.164818373 16 1.547473189 17 ...
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