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Articles by Nizamuddin Siddiqui
Page 80 of 196
How to replace $ sign combined with some specific values in an R data frame?
Sometimes we get very dirty data and that is the reason data analysis is a difficult task. Most of the data scientists look for clean data but it is almost impossible due to data warehouses often just focus on the data availability instead of the quality of data. One of the head scratching situations is getting an unnecessary value placed at different position in a random manner, $ sign is also a that type of value. We can remove this from an R data frame by using lapply function.ExampleConsider the below data frame:> x y df1 df1Outputx y 1 C ...
Read MoreHow to name a data frame column with a vector value that has the same name in R?
To change the column name of a data frame in R, we can use setNames function. For example, if we have a data frame called df that contains column x and we want to change it to value “Ratings” which is stored in a vector called x then we can use the code df x y yOutput x 1 3 2 8 3 3 4 9 5 5 6 5 7 10 8 2 9 6 10 6 11 3 12 5 13 9 14 1 15 1 16 6 17 2 18 6 19 10 20 6Changing x in y to Ratings:Example> y yOutputRatings 1 3 2 8 3 3 4 9 5 5 6 5 7 10 8 2 9 6 10 6 11 3 12 5 13 9 14 1 15 1 16 6 17 2 18 6 19 10 20 6Let’s have a look at another example:Example> S df_Salary df_SalaryOutput S 1 31827 2 24697 3 45790 4 45345 5 22294 6 30749 7 37721 8 33535 9 45941 10 24028 11 48927 12 33818 13 49152 14 43334 15 20294 16 29664 17 23358 18 20475 19 39355 20 40386Changing S in df_Salary to Salary:Example> df_Salary df_SalaryOutputSalary 1 31827 2 24697 3 45790 4 45345 5 22294 6 30749 7 37721 8 33535 9 45941 10 24028 11 48927 12 33818 13 49152 14 43334 15 20294 16 29664 17 23358 18 20475 19 39355 20 40386
Read MoreHow to create a matrix using vector generated with rep function in R?
Matrix can be only generated if we pass an even number of elements for it. If we want to create a matrix using vector generated with rep function then the length of this vector must be divisible by 2. For example, if we have a vector x that is created with rep function and it’s length is 20 then the matrix say M of size 10x2 using that vector can be constructed by using matrix(x, ncol=2).Example 1> x M1 M1Output[, 1] [, 2] [1, ] 10 10 [2, ] 4 4 [3, ] 7 7 [4, ] 3 3 [5, ...
Read MoreHow to replace missing values in a column with corresponding values in other column of an R data frame?
Often, we get missing data for analysis and we need to replace those missing values with something. Sometimes, we might want to replace them with the corresponding values in other column especially in situations when both the columns depict similar characteristics. This type of replacement can be easily done with the help of mutate function of dplyr package as shown in the below examples.Example1Consider the below data frame:> set.seed(214) > x1 x2 df1 df1Output x1 x2 1 4 75 2 8 24 3 5 38 4 4 38 5 7 NA 6 6 24 7 10 75 8 4 75 9 ...
Read MoreHow to remove multiple rows from an R data frame using dplyr package?
Sometimes we get unnecessary information in our data set that needs to be removed, this information could be a single case, multiple cases, whole variable or any other thing that is not helpful in achieving our analytical objective, hence we want to remove it. If we want to remove such type of rows from an R data frame with the help of dplyr package then anti_join function can be used.ExampleConsider the below data frame:> set.seed(2514) > x1 x2 df1 df1Output x1 x2 1 5.567262 4.998607 2 5.343063 4.931962 3 2.211267 5.034461 ...
Read MoreHow to create normal quantile-quantile plot for a logarithmic model in R?
How to create normal quantile-quantile plot for a logarithmic model in R?A logarithmic model is the type of model in which we take the log of the dependent variable and then create the linear model in R. If we want to create the normal quantile-quantile plot for a logarithmic model then plot function can be used with the model object name and which = 2 argument must be introduced to get the desired plot.Example1> x1 x1Output[1] 4.735737 3.631521 5.522580 5.538314 5.580952 4.341072 4.736899 2.455681 [9] 4.042295 5.534034 4.717607 6.146558 4.466849 5.444437 5.390151 4.491595 [17] 4.227620 4.223362 5.452378 5.690660 5.321716 5.269895 ...
Read MoreHow to set the diagonal elements of a matrix to 1 in R?
First thing we need to understand is diagonal elements are useful only if we have a square matrix, otherwise it would not make sense to set diagonal elements, this is known to almost all mathematicians but some freshman might get confused because we can create diagonal in a non-square matrix which should not be called a diagonal. In R, we can set the diagonal elements of a matrix to 1 by using diag function.Example1> M1 M1Output [, 1] [, 2] [, 3] [, 4] [, 5] [1, ] 1 6 11 16 21 [2, ...
Read MoreHow to create a barplot with gaps on Y-axis scale in R?
If we want to have gaps on Y-axis scale in a barplot then it cannot be done in base R. For this purpose, we can make use of gap.barplot function of plotrix package. The gap.barplot function is very handy, we just need to pass the vector for which we want to create the barplot and the gap values simply by using gap argument.Loading plotrix package:> library(plotrix)Example1> x xOutput[1] 2 6 5 4 7 2 5 2 5 2 8 6 8 13 3 5 7 7 5 6> gap.barplot(x, gap=c(2, 4)) ylim 0 11Warning message:In gap.barplot(x, gap = c(2, 4)) ...
Read MoreHow to fix the coefficient of an independent variable in R?
While doing the analysis we might know the variation in an independent variable or we might want to understand how other independent variables behave if we fix a certain variable. Therefore, we can fix the coefficient of an independent variable while creating the model and this can be done by using offset function with the coefficient of the variable for which we want to fix the value of the coefficient.ExampleConsider the below data frame:> set.seed(854) > x1 x2 y1 df1 df1Output x1 x2 y1 ...
Read MoreHow to create a point chart with point size increment based on the position of the point in R?
The cex argument is used to increase or decrease the point size in a point chart created in base R. If we want to create a point chart with points of size in increment manner then we can pass a vector of the same size as the vector for which we want to create the point chart. For example, if we have a vector x that contains 10 elements then cex will be set as cex=1:10.Example1> x plot(x, cex=1:10, xlim=c(1, 12), ylim=c(-2, 12))Output:ExampleLet’s have a look at another example:> y plot(y, cex=1:10, xlim=c(1, 12), ylim=c(-1, 12))Output:
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