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Articles by Nizamuddin Siddiqui
Page 43 of 196
How to delete a row from an R data frame if any value in the row is greater than n?
To delete a row from an R data frame if any value in the row is greater than n can be done by using the subsetting with single square brackets and negation operator. We will subset the values that are greater than n and then take the negation of the subset as shown in the below given examples.Example 1Following snippet creates a sample data frame −x1
Read MoreHow to find the sum product of two matrix by row in R?
To find the sum product of two matrix by row in R, we can use rowSums function by passing the multiplication of the matrices.For example, if we have two matrices say Matrix1 and Matrix2 then, the sum product of these two matrices by row can be found by using the following command −rowSums(Matrix1*Matrix2)Example 1Following snippet creates a matrix −M1
Read MoreHow to multiply each value in a column by a constant in R?
To multiply each value in a column by a constant, we can use multiplication sign *.For example, if we have a data frame called df that contains a column say x. Now, if we want to multiply each value in x with 10 then we can use the below mentioned command −df$x
Read MoreHow to deal with error invalid xlim value in base R plot?
The error invalid xlim value occurs when we incorrectly provide the xlim values, these values are not used in sequence, we just need to provide first and the last value. For Example, if we want to create a point chart of 1 to 5 with xlim having values between -5 to 15 then we can use the command as follows −plot(1:5, xlim=c(-5:15))ExampleAdd the following code to the above command −plot(1:10) OutputIf you execute the above given command, it generates the following Output −Add the following code to the above snippet −plot(1:10) plot(1:10, xlim=c(-15:15)) Error in plot.window(...) : invalid 'xlim' value ...
Read MoreExtract string vector elements up to a fixed number of characters in R.
To extract string vector elements up to a fixed number of characters in R, we can use substring function of base R.For Example, if we have a vector of strings say X that contains 100 string values and we want to find the first five character of each value then we can use the command as given below −substring(X,1,5)Example 1Following snippet creates a sample data frame −x1
Read MoreHow to create histogram for discrete column in an R data frame?
To create histogram for discrete column in an R data frame, we can use geom_bar function of ggplot2 package and set the width to 1 also passing same column for x and y in aes.For example, if we have a data frame called df that contains a discrete column say x then the histogram for data in x can be created by using the below given command −ggplot(df,aes(x,x))+geom_bar(stat="identity",width=1)ExampleFollowing snippet creates a sample data frame −x
Read MoreHow to display X-axis tick marks as minimum and maximum only without their values using plotly in R?
To display X-axis tick marks as minimum and maximum only without their values using plotly, we can use layout function of plot_ly package where we can pass the values for minimum and maximum using xaxis argument and the text using ticktext argument as shown in the below example.ExampleFollowing snippet creates a sample data frame −x
Read MoreHow to find the intersection of elements in a string vector in R?
If we have a string vector that contains more than one element then there might exists some common values in all the elements. If we want to find those values then intersect function can be used along strsplit function and Reduce function.Check out the below Examples to understand how it can be done.Example 1>x1=c("Data science is an interdisciplinary field that uses scientific methods, processes, algorithms and systems to extract knowledge and insights from structured and unstructured data, and apply knowledge and actionable insights from data across a broad range of application domains.", "Data science is the domain of study that ...
Read MoreHow to find the sum of values based on two groups if missing values are present in R?
To find the sum of values based on two groups if missing values are present, we can use group_by and summarise function of dplyr package.For example, if we have a data frame called df that contains a numerical column say Num and two grouping columns say Grp1 and Grp2 then, the sum of values in Num based on Grp1 and Grp2 if missing values are present in df can be found by using the below mentioned command −df%>%group_by(Grp1, Grp2)%>%summarise(Sum=sum(Num, na.rm=TRUE))Example 1Following snippet creates a sample data frame −grp1
Read MoreHow to deal with error “var(x) : Calling var(x) on a factor x is defunct.” in R?
The error “Calling var(x) on a factor x is defunct” occurs when we try to apply a numerical function on factor data.For example, if we have a factor column in a data frame then applying numerical functions on that column would result in the above error. To deal with this problem, we can use as.numeric function along with the numerical function as shown in the below examples.Example 1Following snippet creates a sample data frame −x
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