Sometimes when we read data in R, the missing values are recorded as blank spaces and it is difficult to replace them with any value. The reason behind this is we need to know how many spaces we have used in place of missing values. If we know that then assigning any value becomes easy.ExampleConsider the below data frame of vectors x and y.> x y df df x y 1 1 2 3 2 3 2 4 1 43 5 2 2 6 3 7 2 3 ... Read More

Correlation matrix helps us to determine the direction and strength of linear relationship among multiple variables at a time. Therefore, it becomes easy to decide which variables should be used in the linear model and which ones could be dropped. We can find the correlation matrix by simply using cor function with data frame name.ExampleConsider the below data frame of continuous variable −> set.seed(9) > x1 x2 x3 x4 x5 df df x1 x2 ... Read More

Ordering columns might be required when we want to manipulate the data. Manipulation can have several reasons such as cross verification, visualisation, etc. We should also be careful when we change anything in the original data because that might affect our processing. To change the order of columns we can use the single square brackets.ExampleConsider the below data frame −> set.seed(1) > Class Grade Score df df   Class Grade Score 1   a     A     68 2   b     B     39 3   c     C      1 4   ... Read More

There are different ways to express any chart. The more information we can provide in a chart, the better it is because a picture says thousand words. Since nobody likes to read a long-reports, we should have better reporting of charts. Therefore, we can add a chart title as well as chart sub-title in ggplot2 to help the readers.ExampleConsider the below data −> set.seed(1) > x table(x) x 2 3 4 5 6 7 8 9 11 1 3 4 2 4 2 2 1 1 > df library(ggplot2)Creating a simple bar chart −> ggplot(df, aes(x))+ + geom_bar()OutputCreating a ... Read More

There are times when duplicated rows in a data frame are required, mainly they are used to extend the data size instead of collecting the raw data. This saves our time but surely it will have some biasedness, which is not recommended. Even though it is not recommended but sometimes it becomes necessary, for example, if it is impossible to collect raw data then we can do it. If we do so then we must specify it in our analysis report. In R, we can use rep function with seq_len and nrows to create a data frame with repeated rows.ExampleConsider ... Read More

Sometimes subsetting of group wise maximum values is required while doing the data analysis and this subset of the data frame is used for comparative analysis. The main objective is to compare these maximums with each other or with a threshold value. In R, we can find the group wise maximum value by using group_by and slice functions in dplyr package.ExampleConsider the below data frame −> x y df head(df, 20) x y 1 S1 1 2 S1 2 3 S1 3 4 S1 4 5 ... Read More

The warning “removed n rows containing missing values” occurs when we incorrectly specify the range of the values for X-axis or Y-axis. We can this range in ggplot function using scale_x_continuous(limits=c(?, ?)) for x axis and scale_y_continuous(limits=c(?, ?)) for y axis. If the range will be larger than the actual data range then there will be no warning otherwise, we will get the warning for the number of missing values.ExampleConsider the below data frame −> set.seed(2) > x y df library(ggplot2)Creating the plot with Y-axis limits from 0 to 5−> ggplot(df, aes(x, y))+ + geom_point()+ + scale_y_continuous(limits=c(0, 5)) Warning message: ... Read More

It is very difficult to join points on a scatterplot with smooth lines if the scatteredness is high but we might want to look at the smoothness that cannot be understood by just looking at the points. It is also helpful to understand whether the model is linear or not. We can do this by plotting the model with loess using plot function.ExampleConsider the below data −> set.seed(3) > x y Model summary(Model) Call: loess(formula = y ~ x) Number of Observations: 10 Equivalent Number of Parameters: 4.77 Residual Standard Error: 8.608 Trace of smoother matrix: 5.27 (exact) Control ... Read More

The standard error of mean is the standard deviation divided by the square root of the sample size. The easiest way to find the standard error of mean is using the formula to find its value.Example> set.seed(1)We will find the standard errors for a normal random variable, sequence of numbers from one to hundred, a random sample, a binomial random variable, and uniform random variable using the same formula. And at the end, I will confirm whether we used the correct method or not for all types of variables we have considered here.> x x [1] -0.6264538 0.1836433 -0.8356286 ... Read More

The inverse of a matrix can be calculated in R with the help of solve function, most of the times people who don’t use R frequently mistakenly use inv function for this purpose but there is no function called inv in base R to find the inverse of a matrix.ExampleConsider the below matrices and their inverses −> M1 M1 M1    [, 1] [, 2] [1, ] 1 3 [2, ] 2 4 > solve(M1) [, 1] [, 2] [1, ] -2 1.5 [2, ] 1 -0.5 > M2 M2 ... Read More