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Articles by Nizamuddin Siddiqui
Page 17 of 196
How to extract the first row of each matrix stored in a list in R?
To extract the first row of each matrix stored in a list in R, we can use lapply function. For example, if we have a list called LIST that contains some matrices then we can find the first row of each matrix by using the command given below − lapply(LIST,'[',1,)Check out the below given example to understand how it can be done.ExampleFollowing snippet creates a list of matrices −M1
Read MoreHow to extract the outliers of a boxplot in R?
To extract the outliers of a boxplot, we can use out function along with the boxplot function. For example, if we have a vector called X which contains some outliers then we can extract those outliers by using the command given below − boxplot(df$X, plot=FALSE)$outThis command will not create a plot as plot is set to FALSE.ExampleFollowing snippet creates a sample data frame −df=data.frame(x=rlnorm(25)) dfThe following dataframe is created − x 1 0.5699270 2 3.5812629 3 0.3507882 4 0.1400328 5 0.7239948 6 2.5494114 7 3.1243611 8 5.3207739 9 0.1672539 10 7.6235529 11 0.4950263 12 1.1713592 13 1.6590328 14 ...
Read MoreHow to replace zero with previous value in an R data frame column?
To replace zero with previous value in an R data frame column, we can use na.locf function of zoo package but to apply this we first need to replace the zero values with NA.For example, if we have a data frame called df that contains a column say Rate then we can use the below commands to replace 0 values in Rate with previous value by using the below given commands − df$Rate[df$Rate==0]
Read MoreCreate scatterplot for two dependent variables and one independent variable in R.
To create scatterplot for two dependent variables and one independent variable, we can use geom_point function and geom_smooth function of ggplot2 package. Both of these functions will be used twice, where we can define the aesthetics of the plot for each dependent variable as shown in the Example below.ExampleFollowing snippet creates a sample data frame −x
Read MoreCreate line chart for mean covered with minimum and maximum in R.
To create line chart for mean covered with minimum and maximum in R, we first need to create columns for row means, row minimum, and row maximum after that geom_line function can be used along with geom_ribbon function of ggplot2 package as shown in the below example.ExampleFollowing snippet creates a sample dataframe.x
Read MoreHow to add two columns if both contains missing values in R?
If we want to add two columns of an R data frame and each of them contains missing values then the addition of columns can be done in one of the following ways −Adding both the column values if they are numeric.Returning numeric if one of the columns has missing value.Returning NA if both the columns have missing value.To this we can take help of apply function and ifelse function as shown in the below given examples.Example 1Following snippet creates a sample data frame −x1
Read MoreHow to take transpose of vectors stored in an R list?
We can take the transpose of vectors stored in an R list by using Map function with do.call. For example, if we have a list called LIST that contains say ten vectors then we can transpose these vectors by using the command given below − do.call(Map,c(f=c,LIST))Check out the below examples to understand how it works.Example 1To take transpose of vectors stored in an R list, use the command given below −List1
Read MoreHow to subset a matrix based on values in a particular column in R?
To subset a matrix based on values in a particular column, we can use single square brackets and provide the row and column values. The column values will be set for the columns that we want to subset and the row value will be set for the values of the column using which we want to subset the matrix.Check out the below example to understand how it works.ExampleFollowing snippet creates a matrix −M
Read MoreHow to highlight outliers in a boxplot in R?
To highlight outliers in a boxplot, we can create the boxplot with the help of Boxplot function of car package by defining the id.method.For example, if we have a vector called V then the boxplot of V with highlighted outliers can be created by using the below given command −Boxplot(~V,id.method="y")Example 1To highlight outliers in a boxplot, use the command given below −library(car) x
Read MoreHow to check if a string contains only one type of character in R?
If a string contains more than one character then all of them could be same or different. If we want to check if a string contains only one type of character, then stri_count_fixed function of stringi package will be used with nchar function.Check out the below given examples to understand how it can be done.Example 1Following snippet creates a sample data frame −Countries
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