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Articles by Nizamuddin Siddiqui
Page 83 of 196
How to extract a data frame's column value based on a column value of another data frame in R?
In data analysis, we encounter many problems with a lot of variations among them. One such problem is we have some information in a place that needs to be checked through a different place and these places can be data frames. Therefore, we can to find a data frame’s column value based on a column value of another data frame. In R, we can easily do it with the help of which function.Examplex2
Read MoreHow to find the position of minimum value in a vector that contains integers as strings in R?
If integer vector is read as strings and we want to find the position of the minimum value in that vector then we need to use as.numeric along with the vector to read it as a numeric vector then use which function for finding the position of the minimum value. For example, if we have a vector x that contains first ten integers as strings then to find the position of the minimum we can use which(as.numeric(x)==min(as.numeric(x))).Example1x1
Read MoreHow to convert a list into an array in R?
To convert a list into an array then firstly we need to unlist the list elements and then use the array function. For example, if we have a list defined as List then it can be converted into an array using the command array(unlist(List)). Suppose the list contain the elements as shown below −1 2 3 4 5 1 2 3 4 5 1 2 3 4 5If we convert this list into an array then the output will be 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5.Example1List1
Read MoreHow to check in R whether a matrix element is present in another matrix or not?
We can use %in% to check whether a matrix element is present in another matrix or not. For example, suppose we have two matrices defined as − M1 1 2 3 1 2 3 1 2 3 M2 1 2 3 4 5 6 7 8 9Then M1%in%M2 will return −[1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUEBut M2%in%M1 will return −[1] TRUE FALSE FALSE TRUE FALSE FALSE TRUE FALSE FALSEExample1M1
Read MoreHow to combine two factor vectors to create one in R?
To combine two factor vectors, we can extract the unique levels of both the vectors then combine those levels. This can be done by using unique function. Also, we can set the levels of the original vectors to the combination of the levels, in this way, we can complete both the vectors with missing levels. Check out the examples below to understand how it works.Example1x1
Read MoreHow to find minimum value in a numerical vector which is written as a character vector in R?
To find the minimum value of a numeric vector we can directly use min function but if the values are read with double-inverted commas then min function does not work. In this case, we will have to use as.numeric with the vector name so that it can be converted to numeric form before finding the minimum value. For example, if we have a character vector that contains 1, 2, 3, and 4 then the minimum can be found as min(as.numeric(x)).Example1x1
Read MoreHow to repeat a random sample in R?
The random sample can be repeated by using replicate function in R. For example, if we have a vector that contains 1, 2, 3, 4, 5 and we want to repeat this random sample five times then replicate(5, x) can be used and the output will be matrix of the below form:[, 1] [, 2] [, 3] [, 4] [, 5] [1, ] 1 1 1 1 1 [2, ] 2 2 2 2 2 [3, ] 3 3 3 3 3 [4, ] 4 4 4 4 4 [5, ] 5 5 5 5 5Example 1> x1 x1Output[1] 1 ...
Read MoreHow to create a vector with lowercase as well as uppercase letters in R?
To create a vector with lowercase we can use the word letters and for uppercase the word LETTERS is used in R. If we want to create a vector with both type of letters then both of these words can be combined using c function and if want to create a vector with randomly sampled values of lowercase and uppercase letters then sample function can be used.Examples> x1 x1Output[1] "A" "B" "C" "D" "a" "b" "c" "d"Example> x2 x2Output[1] "A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N" "O" "P" "Q" "R" "S" [20] "T" ...
Read MoreHow to find the cumulative sums by using two factor columns in an R data frame?
Generally, cumulative sums are calculated for a single variable and in some cases based on a single categorical variable, there are very few situations when we want to do it for two categorical variables. If we want to find it for two categorical variables then we need to convert the data frame to a data.table object and use the cumsum function to define the column with cumulative sums.ExampleConsider the below data frame:> set.seed(1361) > Factor1 Factor2 Response df1 df1OutputFactor1 Factor2 Response 1 A T2 9 2 B T1 8 3 B T1 2 4 A T2 3 5 B T1 ...
Read MoreHow to set the legends using ggplot2 on top-right side in R?
The default position of legend in a plot created by using ggplot2 is right hand side but we can change the position by using theme function that has legend.position argument and legend.justification argument. To set the legend on top-right side we can use legend.position="top" and legend.justification="right".ExampleConsider the below data frame:Consider the below data frame:> x freq df dfOutputx freq 1 Mango 212 2 Guava 220 3 Pomegranate 218Loading ggplot2 package and creating bar chart with legend:> library(ggplot2) > ggplot(df, aes(x, freq, fill=x))+geom_bar(stat="identity")Output:Creating the bar chart with legend on top-right hand side of the chart:Example> ggplot(df, aes(x, freq, fill=x))+geom_bar(stat="identity")+theme(legend.position="top", legend.justification="right")Output:
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