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Articles by Nizamuddin Siddiqui
Page 61 of 196
How to create reverse of a number in R?
To create reverse of a number, we can use stri_reverse function of stringi package. For example, if we have a vector called x that contain some numbers then the reverse of these numbers will be generated by using the command stri_reverse(x). But the output will be in character form, if we want to have numeric values then as.numeric function can be used.library(stringi)Examplex1
Read MoreHow to convert a character data frame to numeric data frame in R?
Sometimes numerical values are recorded as character values and we need to convert them to numeric type before starting our analysis. This is also possible for a whole data frame in R. Therefore, we can use sapply function to convert the columns of the data frame to numeric type and save the output in a data frame by reading it with as.data.frame.Example1Consider the below data frame −x
Read MoreHow to create bins for a continuous vector in R?
To create the bins for a continuous vector, we can use cut function and store the bins in a data frame along with the original vector. The values in the cut function must be passed based on the range of the vector values, otherwise, there will be NA’s in the bin values. For example, if we have a vector that contains 0.55 and we do not use 0 in the cut function then the first bin will be NA. Check out the below examples to understand how to properly do it.Example1x1
Read MoreHow to convert matrix rows into a list in R?
Depending on our objective, a matrix rows might be needed to converted into a list that means each row will be an element of the list. This can be done by using the function as.list but firstly we need to convert the matrix into data frame after transposing. For example, if we have a matrix called M then it’s rows will be converted to a list using the command writtem below −as.list(data.frame(t(M)))Example1M1
Read MoreHow to find the mean of multiple columns based on a character column in R?
If we have a character column that means we are more likely to have duplicated values in that column hence finding the mean of numerical columns based on the values in character column cannot be done directly. For this purpose, we can use aggregate function as shown in the below examples.Example1Consider the below data frame −set.seed(214) x1
Read MoreHow to create a line chart with mean and standard deviation using ggplot2 in R?
Sometimes we have mean and standard deviation given for groups or factors, these are generally obtained from previous research studies and is referred to as the secondary data. In this case. the line chart with mean and standard deviation using ggplot2 can be created by defining the minimum and maximum inside geom_error function of ggplot2 package, where the difference between mean and standard deviation defines the standard deviation if the minimum is set as mean minus one standard deviation and the maximum is set as mean plus one standard deviation.ExampleConsider the below data frame −Group
Read MoreHow to find the sum by distinct column for factor levels in an R data frame?
If the data frame contains a factor column and some numerical columns then we might want to find the sum of numerical columns for the factor levels. For this purpose, we can use aggregate function. For example, if we have a data frame df that contains a factor column defined by Group and some numerical columns then the sum by distinct column for factor levels can be calculated by using aggregate(.~Group,data=df,sum)Example1Class
Read MoreHow to replace missing values with row means in an R data frame?
If we have similar characteristics in each column of an R data frame then we can replace the missing values with row means. To replace the missing values with row means we can use the na.aggregate function of zoo package but we would need to use the transposed version of the data frame as na.aggregate works for column means.Example1Consider the below data frame −x1
Read MoreHow to create a random sample of week days in R?
To create a vector of weekdays we can use the command weekdays(Sys.Date()+0:6) and if we want to create a random sample of week days then sample function can be used along with the weekdays command. For example, if we want to create a random sample of 20 days then it can be done as sample(weekdays(Sys.Date()+0:6),20,replace=TRUE).ExamplesExample1
Read MoreHow to check if a variable contains number greater than 1 in an R data frame?
The variables in an R data frame are referred to as the columns of the data frame. Sometimes we have a threshold value for a particular column and we need to check whether all the values in that column are greater than or less than the threshold. For this purpose, we can make use of ifelse function as shown in the below examples.Example1y
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