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Articles by Nizamuddin Siddiqui
Page 75 of 196
How to visualize a data frame that contains missing values in R?
If a data frame contains missing value then visualising it in base R is not easily possible but we can make use of visdat package for this purpose. The vis_dat function of visdat package helps to visualize any data frame even if it contains missing values. For example, if a data frame df contains missing value then it can be visualized as vis_dat(df).Example1Consider the below data frame −> x1 x2 x3 df1 df1Output x1 x2 x3 1 1 23 10 2 1 23 NA 3 NA NA 10 4 NA NA 10 5 1 24 NA 6 2 22 NA ...
Read MoreHow to create a plot title with unicode characters using ggplot2 in R?
If we want to use unicode characters in the title for a plot created with the help of ggplot2 package then the ggtitle function will be used combined with functions called expression and paste. Using the expression and paste functions, we can write unicode characters for the title of the plot. Check out the below examples to understand how it works.ExampleConsider the below data frame −> x y df dfOutput x y 1 3.4501307 6.354644 2 2.1561511 5.349282 3 4.5018653 6.080046 4 2.5512959 5.957558 5 3.6818738 5.749713 6 ...
Read MoreWhat are levels in a column of a data frame in R?
Most people get confused about levels and characters in R, especially the newbies. The difference is that levels specifically define the factor levels of a factor column and the characters are simple the character column that is not a factor or is not used as a factor but can be converted to a factor.ExampleConsider the below data frame −> x1 x2 df1 df1Outputx1 x2 1 B B 2 B A 3 D D 4 D C 5 C A 6 D C 7 A D 8 D B 9 D C 10 B B 11 C B 12 D A ...
Read MoreWhat is the difference between ls() command and objects() command in R?
They are actually no difference between the two commands as they give the same result that is the number of objects in the current workspace. If we have five different type of objects say a data frame, a matrix, a list, a data.table object, and a vector then both the commands will give the names of these objects.ExampleConsider the below objects −> x1 x2 df1 df1Outputx1 x2 1 A A 2 D A 3 C D 4 A A 5 B C 6 B D 7 D D 8 D C 9 B D 10 B A 11 D B ...
Read MoreHow to detach a package in R?
To detach a package in R, we can simply use the detach function. But we need to remember that once the package will be detached there is no way to use any of the functions of that particular package. We make this mistake if we forget about detachment. For example, if we detach ggplot2 package using detach function detach(package:ggplot2, unload=TRUE) and again run the ggplot or qplot function then there will be an error.ExampleConsider the below data frame −> x y df dfOutputx y 1 -0.09124881 0.8106691 2 -0.20521435 -1.0067072 3 -1.07904498 1.3867400 4 1.34461945 -1.4676405 5 -0.21731862 0.5801624 6 ...
Read MoreHow to find the p-value using F statistic in R?
The F statistic has two degrees of freedom, one for the numerator and one for the denominator and the F distribution is a right-tailed distribution. Therefore, we need to use the F-statistic, the degrees of freedoms, and the lower.tail=FALSE argument with pf function to find the p-value for a F statistic.Examples> pf(5, 1, 99, lower.tail=F) > pf(5, 1, 24, lower.tail=F) > pf(5, 1, 239, lower.tail=F) > pf(5, 5, 239, lower.tail=F) > pf(5, 5, 49, lower.tail=F) > pf(12, 5, 49, lower.tail=F) > pf(120, 5, 49, lower.tail=F) > pf(120, 1, 49, lower.tail=F) > pf(120, 1, 149, lower.tail=F) > pf(3, 1, 149, lower.tail=F) ...
Read MoreHow to find the column names and row names from a matrix in R?
The rownames and colnames functions are used to define the corresponding names of a matrix and if we want to extract those names then the same function will be used. For example, if we have a matrix called M that has row names and column names then these names can be found by using rownames(M) and colnames(M).Example> M1 M1Output[, 1] [, 2] [, 3] [, 4] [, 5] [, 6] [, 7] [, 8] [, 9] [, 10] [1, ] 1 11 21 31 41 51 61 71 81 91 [2, ] 2 12 22 32 42 52 62 72 ...
Read MoreHow to create boxplot for matrix columns in R?
To create a boxplot for data frame columns we can simply use boxplot function but it cannot be done directly for matrix columns. If we want to create boxplot for matrix columns then we need to convert the matrix into data frame and then use the boxplot function. For example, if we have a matrix called M then the boxplot for columns in M can be created by using boxplot(as.data.frame(M)).Example> M MOutput[,1] [,2] [,3] [,4] [,5] [1,] 1.688556 1.697216 1.9469573 1.873956 2.010246 [2,] 1.655357 1.927145 2.0937415 2.273638 1.966972 [3,] 1.886917 1.182852 2.0291452 2.507944 2.338664 [4,] 2.013053 1.995526 1.8122830 2.531708 2.483359 [5,] 1.812015 1.950053 1.8902859 2.453222 2.123253 [6,] 1.781764 1.786285 2.3384120 2.275382 2.509708 [7,] 1.836378 1.192781 1.5382031 2.012324 2.290340 [8,] 2.061482 1.705481 2.5542404 1.958202 1.991252 [9,] 2.162214 1.958862 1.8096081 1.810033 1.856942 [10,] 1.897020 1.614834 2.3407207 2.199068 1.807968 [11,] 2.491147 2.317192 2.4486029 2.131722 1.947841 [12,] 1.860307 1.932982 2.2034280 1.982581 2.720482 [13,] 1.814205 2.214286 1.6917036 1.854341 2.150684 [14,] 1.224437 1.800944 1.7600398 1.503382 2.775012 [15,] 2.309462 2.534766 1.5111472 2.058761 1.823550 [16,] 2.190564 1.588298 1.8854163 1.694651 1.939035 [17,] 2.521611 2.339012 2.2959581 2.501148 1.951673 [18,] 1.808799 2.314207 1.8704730 1.937851 1.877917 [19,] 2.476626 1.806194 2.7111663 2.156506 1.521197 [20,] 1.819725 1.633549 1.9438948 2.213533 2.247944 [21,] 2.412117 1.797531 2.5320892 1.889267 2.586912 [22,] 1.679395 2.276218 1.6120445 1.648766 1.889033 [23,] 2.286285 2.221312 0.9408758 1.896072 1.996449 [24,] 2.274975 2.398884 2.0146319 1.814092 2.350100 [25,] 2.106620 1.640401 1.6416454 2.452356 1.638885 [26,] 1.556329 1.706762 1.8324196 2.348518 1.593293 [27,] 2.171867 1.707615 1.9667116 2.191344 1.595531 [28,] 1.796751 2.753674 2.1741976 1.623239 2.399018 [29,] 2.635992 2.180735 2.2114669 2.258419 2.277367 [30,] 1.874671 2.113165 2.3653358 2.231705 1.919449Example> boxplot(as.data.frame(M))Output
Read MoreHow to identify the difference between Kolmogorov Smirnov test and Chi Square Goodness of fit test in R?
The Chi Square Goodness of fit test is used to test whether the distribution of nominal variables is same or not as well as for other distribution matches and on the other hand the Kolmogorov Smirnov test is only used to test to the goodness of fit for a continuous data. The difference is not about the programming tool, it is a concept of statistics.Example> x xOutput[1] 0.078716115 -0.682154062 0.655436957 -1.169616157 -0.688543382 [6] 0.646087104 0.472429834 2.277750805 0.963105637 0.414918478 [11] 0.575005958 -1.286604138 -1.026756390 2.692769261 -0.835433410 [16] 0.007544065 0.925296720 1.058978610 0.906392907 0.973050503Example> ks.test(x, pnorm) One-sample Kolmogorov-Smirnov test data: x D ...
Read MoreHow to find the sum of division in R if zero exists in the vectors?
To find the sum of division if zero exists in the vectors, we need to assign NA to zeros in both the vectors and then use the sum function with na.rm set to TRUE. For example, if we have two vectors x and y that contains some zeros then we can divide x by y using the below commands −x[x==0] y yOutput[1] 1 5 3 1 9 1 3 8 9 0 1 7 3 2 3 3 2 9 3 1 9 5 5 2 5 4 4 7 4 5 9 1 9 9 4 2 3 [38] ...
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