Server Side Programming Articles

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How to add regression residuals to data frame in R?

Nizamuddin Siddiqui
Nizamuddin Siddiqui
Updated on 11-Mar-2026 4K+ Views

To add regression residuals to data frame in R, we can follow the below steps −First of all, create a data frame.Then, use lm function to create the regression model and find the residuals using resid function and adding them to the data frame with $ operator.Create the data frameLet's create a data frame as shown below −x

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How to truncate character vector with three dots after n characters in R?

Nizamuddin Siddiqui
Nizamuddin Siddiqui
Updated on 11-Mar-2026 294 Views

To truncate character vector with three dots after n characters can be done with the help of str_trunc function of stringr package. For example, if we have a character vector say x and each value containing 10 characters then truncating those values with three dots after 5 characters can be done by using the command str_trunc(x, 8).Example1> x1 x1Output[1] "rstuvwxyz" "rstuvwxyz" "abcbefgh" "rstuvwxyz" "ijklmnopq" "ijklmnopq" [7] "ijklmnopq" "rstuvwxyz" "rstuvwxyz" "rstuvwxyz" "rstuvwxyz" "abcbefgh" [13] "rstuvwxyz" "abcbefgh" "abcbefgh" "ijklmnopq" "ijklmnopq" "ijklmnopq" [19] "ijklmnopq" "rstuvwxyz" "rstuvwxyz" "abcbefgh" "abcbefgh" "ijklmnopq" [25] "ijklmnopq" "ijklmnopq" "rstuvwxyz" "rstuvwxyz" "rstuvwxyz" "rstuvwxyz" [31] "rstuvwxyz" "abcbefgh" "abcbefgh" "rstuvwxyz" "rstuvwxyz" "abcbefgh" ...

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How to get the colour name from colour code in R?

Nizamuddin Siddiqui
Nizamuddin Siddiqui
Updated on 11-Mar-2026 654 Views

To get the color name from color code, we can use the color_id function of plotrix package. If we have a vector of colour codes say x then the colour name can be found by using the command sapply(x, color.id).Example> x xOutput[1] "#FF0000" "#FF1F00" "#FF3D00" "#FF5C00" "#FF7A00" "#FF9900" "#FFB800" [8] "#FFD600" "#FFF500" "#EBFF00" "#CCFF00" "#ADFF00" "#8FFF00" "#70FF00" [15] "#52FF00" "#33FF00" "#14FF00" "#00FF0A" "#00FF29" "#00FF47" "#00FF66" [22] "#00FF85" "#00FFA3" "#00FFC2" "#00FFE0" "#00FFFF" "#00E0FF" "#00C2FF" [29] "#00A3FF" "#0085FF" "#0066FF" "#0047FF" "#0029FF" "#000AFF" "#1400FF" [36] "#3300FF" "#5200FF" "#7000FF" "#8F00FF" "#AD00FF" "#CC00FF" "#EB00FF" [43] "#FF00F5" "#FF00D6" "#FF00B8" "#FF0099" "#FF007A" "#FF005C" "#FF003D" [50] "#FF001F"Loading plotrix ...

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How to sort a vector in R based on manual position of elements?

Nizamuddin Siddiqui
Nizamuddin Siddiqui
Updated on 11-Mar-2026 704 Views

To sort a vector based on manual position of elements, we can use order function along with the factor function. The factor function will help us to arrange the vector elements in the order we want by defining the levels as vector elements and order function will order them. Check out the below examples to understand how it works.Example1> x1 x1Output[1] 0 1 0 0 1 2 1 2 3 1 2 2 2 4 3 1 4 1 0 1 1 3 3 0 0 4 4 2 4 2 4 2 0 4 0 1 1 [38] 4 ...

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How to format all decimal places in an R vector and data frame?

Nizamuddin Siddiqui
Nizamuddin Siddiqui
Updated on 11-Mar-2026 4K+ Views

To format all decimal places in an R vector and data frame, we can use formattable function of formattable package where we can specify the number of digits after decimal places. For example, if we have a numerical vector say x then the values in x can be formatted to have only 2 decimal places by using the command formattable(x,format="f",digits=2).Example1Loading formattable package −library(formattable)x1

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How to create a date vector with randomization in R?

Nizamuddin Siddiqui
Nizamuddin Siddiqui
Updated on 11-Mar-2026 296 Views

To create a date vector with randomization, we can use sample function but the dates need to be read with as.Date function. For example, if we have 2 dates say 2021-01-01 and 2021-02-02 then a vector with randomization of these three dates can be created by using the command −sample(c(as.Date("2021-01-01"),as.Date("2021-02-02")),100,replace=TRUE)Example1Date1

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How to find the count of a particular character in a string vector in R?

Nizamuddin Siddiqui
Nizamuddin Siddiqui
Updated on 11-Mar-2026 235 Views

To find the count of a particular character in a string vector we can use nchar function along with gsub. For example, if we have a vector called x that contains string such India, Russia, Indonesia then we can find the number of times character i occurred then we can use the command nchar(gsub("[^i]","",x)) and the output will be 1 1 1 because first I’s in India and Indonesia will not be considered as they are in uppercase.Example1x1

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Find shortest safe route in a path with landmines in C++

sudhir sharma
sudhir sharma
Updated on 11-Mar-2026 982 Views

In this problem, we are given a matrix mat[][]. It defines a path with landmines which are marked as 0. Our task is to Find shortest safe route in a path with landmines.While traversing through the safe path, we need to avoid walking adjacent cells of the landmine (left, right, above and bottom) for being unsafe.All valid moves while traversing the path are −- Left : mat[i][j] => mat[i-1][j] - Right : mat[i][j] => mat[i+1][j] - Top : mat[i][j] => mat[i][j - 1] - Bottom : mat[i][j] => mat[i][j + 1]Let’s take an example to understand the problem, Inputmat[][] = ...

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How to find the frequency table for factor columns in an R data frame?

Nizamuddin Siddiqui
Nizamuddin Siddiqui
Updated on 11-Mar-2026 852 Views

If we have factor columns in an R data frame then we want to find the frequency of each factor level for all the factor columns. This can be done with the help of sapply function with table function. For example, if we have a data frame called df that contains some factor columns then the frequency table for factor columns can be created by using the command sapply(df, table).Example1Consider the below data frame −> x1 x2 df1 df1Output   x1 x2 1  D  a 2  D  b 3  D  c 4  D  b 5  D  c 6  C  a 7 ...

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How to convert an old data frame to new data frame in R?

Nizamuddin Siddiqui
Nizamuddin Siddiqui
Updated on 11-Mar-2026 619 Views

To convert an old data frame to a new data frame, we can simply set the new name. For example, if we have a data frame called df and want to convert it to a new one let’s say df_new then it can be done as df_new x1 x2 df1 df1Output x1 x2 1 8 6 2 4 9 3 3 2 4 3 5 5 7 4 6 4 8 7 8 6 8 12 12 9 8 6 10 ...

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