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Articles by Nizamuddin Siddiqui
Page 57 of 196
How to find unique matrices in a list in R?
A list can contain many types of elements such as vectors, matrices, data frames etc. If we have matrices in a list then to find unique matrices in that list, we can simply use unique function. For example, if we have a list called LIST that contains matrices having some duplicate matrices then unique matrices can be extracted by using unique(LIST).Example1list(M1=matrix(1:25, ncol=5), M2=matrix(1:25, ncol=5), M3=matrix(1:25, ncol=5), M4=matrix(rpois(25, 5), ncol=5)) List1Output$M1 [, 1] [, 2] [, 3] [, 4] [, 5] [1, ] 1 6 11 16 21 [2, ] 2 7 12 17 22 [3, ] 3 8 13 18 ...
Read MoreHow to find mean and standard deviation from frequency table in R?
To find the mean and standard deviation from frequency table, we would need to apply the formula for mean and standard deviation for frequency data. For example, if we have a data frame called df that contains a column x for units and frequency for counts then the mean and standard deviation can be calculated as −Mean = sum(df$x*df$frequency)/sum(df$frequency) SD = sqrt(sum((df$x−Mean)**2*df$frequency)/(sum(df$frequency)−1)) respectively.Example1x
Read MoreHow to export data frame in R to excel?
To export data frame in R to excel can be done with the help of write.xlsx function of xlsx package. We would need to pass the data frame name, the file name and the sheet name in which we want to save the data frame. For example, if we have a data frame called df with file name Excel_df and on sheet1 then the data frame will be saved by using the below command −write.xlsx(df, file="Excel_df.xlsx", sheetName = "Sheet1")Consider the below data frame −Examplex
Read MoreHow to plot matrix columns as lines in base R?
To plot matrix columns as lines in base R, we can use matplot function but we need to read the matrix as a data frame using as.data.frame function and for creating lines the type argument will be used. For example, if we have a matrix called M then the columns of M can be plotted as lines using the command matplot(as.data.frame(M),type="l").Consider the below data frame −ExampleM
Read MoreHow to save a csv and read using fread in R?
To save a csv file, we can use write.csv function in R and if we want to read it using fread then fread function will be used with the name of the csv file. The benefit of reading the csv file with fread function is that there will be a variable added to the original csv file which contains the id as integers starting from 1 to the length of column values.Consider the below data frame −Examplex
Read MoreHow to hide NA values in an R matrix?
The hiding of NA values does not mean removal of NA values. If we have some NA values in an R matrix then we can hide them using blanks with double quotes. For example, suppose we have a matrix called M that contains some NA values then M can be printed by hiding NA value using print.table(M,na.print="")ExampleM1
Read MoreHow to fill NA values with previous values in an R data frame column?
To fill NA values with next and previous values, we can use na.locf function of zoo package with fromLast = TRUE. This is the situation of a column as shown below −x 0 NA NA 1 1 NA 0 1The output after filling NA values with next and previous values will be −x 0 0 0 1 1 1 0 1Consider the below data frame −Examplex1
Read MoreHow to define the breaks for a histogram using ggplot2 in R?
To manually define the breaks for a histogram using ggplot2, we can use breaks argument in the geom_histogram function. While creating the number of breaks we must be careful about the starting point and the difference between values for breaks. This will define the number of bars for histogram so it should be taken seriously and should be according to the distribution of the data.Consider the below data frame −Examplex
Read MoreHow to create group names for consecutively duplicate values in an R data frame column?
The grouping of values can be done in many ways and one such way is if we have duplicate values or unique values then the group can be set based on that. If all the values are unique then there is no sense for grouping but if we have varying values then the grouping can be done. For this purpose, we can use rleid function as shown in the below examples.Example1Consider the below data frame −> x df1 df1Output x 1 2 2 1 3 2 4 2 5 1 6 0 ...
Read MoreHow to use pnorm function on data frame columns in R?
The pnorm function is used to find the probability for a normally distributed random variable. Probabilities such as less than mean, greater than mean, or probability between left- and right-hand side of the mean. If we want to use pnorm function on data frame columns then apply function can help us.Consider the below data frame −Examplex1
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