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Articles by Nizamuddin Siddiqui
Page 92 of 196
How to extract axes labels for the plot drawn using ggplot2 in R?
When we create a plot using ggplot2, the axes labels are automatically generated for both the axes. We might want to use those axes labels for report writing or some other purpose, therefore, extraction of those labels for a plot created by using ggplot2 package can be found by using the ggplot_build function as shown in the below example but we need to save the plot in an object.Consider the below data frame −Example Live Demox
Read MoreHow to change the default type of points for scatterplot using ggplot2 in R?
To change the defaults for ggplot2 geoms, we need to use update_geom_defaults function. If we want to change the shape of points for scatterplot, we can use the below syntax −update_geom_defaults("point",list(shape=”point_shape_number”))The point shape number ranges from 0 to 25. We can change that according to our need.Consider the below data frame −Example Live Demox
Read MoreHow to create boxplot for list elements using ggplot2 in R?
If list elements are of equal size having numerical values then the boxplot for each element can be created by using ggplot2 but before creating the boxplot we would need to convert the list to a data frame. The conversion of list elements to a data frame will be done by unlisting of elements and creating two columns, one for categories and one for response variable. Check out the below example to understand how it works.Consider the below list −Example Live DemoList
Read MoreHow to create boxplot for a list object in base R?
A list object can contain multiple elements of data, also the size of the data may vary. If a list object has numerical vectors then the boxplot for each of the elements can be created simply by using boxplot function. For example, if we have a list object called LIST that contains five numerical vectors then the boxplot for each of the vectors can be created by using the command boxplot(LIST)Example Live DemoList
Read MoreHow to change the first value for each group in data.table object in R?
To change the first value for each group in data.table object, we can use single square brackets for accessing and changing the value to desired value. For example, if we have a data.table object called DT that contains a group column defined by Class and a numerical column defined by Response then the first value of Response for each Class can be set to say 5 by using the command DT[,Response:=c(2,Response[-]),by=Class]Consider the below data.table object −Examplelibrary(data.table) Group
Read MoreHow to create a plot of binomial distribution in R?
A binomial distribution is based on the distribution of success and failure, the other two parameters of binomial distribution are the sample size and the probability of success. To create a plot of binomial distribution, we first need to define the density of the binomial distribution using dbinom function. The plotting can be done by using plot function with success and the density as shown in the below examples.Examplex
Read MoreHow to remove duplicate rows in an R data frame if exists in two columns?
If two values are repeated in a column that means there are many same values in that column but if those values are repeated in column as well as rows then they are called duplicated rows in two columns. To remove duplicate rows in an R data frame if exists in two columns, we can use duplicated function as shown in the below examples.Consider the below data frame −Example Live Demox1
Read MoreHow to display negative labels below bars in barplot using ggplot2 in R?
Be default, the labels on the plot are represented without sign in a barplot that is created by using ggplot2 but we might want to display the sign of the labels especially in cases where we have some negative values. This can be done with the help of geom_text function of ggplot2 package as shown in the below example.Consider the below data frame −Example Live Demox
Read MoreHow to add a row to a frame from another data frame in R?
Sometimes we want to add new data to original data frame in situations such as we need more data for analysis, looking for comparison between small size and large size data, or some data is missing in the original data and hence need more to be added from other data sets. One such thing would be adding a new to an existing data frame from another data frame. It can be done with the help of rbind function as shown in the below example.Consider the below data frames df1 and df2 −Example Live Demox
Read MoreHow to deal with missing column for row names when converting data frame to data.table object in R?
To deal with missing column of row names when converting data frame in R to data.table object, we need to use keep.rownames argument while converting the data frame. For example, if we have a data frame called df that needs to be converted to a data.table object without missing row names then we can use the below command −data.table(df,keep.rownames=TRUE)Examplelibrary(data.table) head(mtcars)Output mpg cyl disp hp drat wt qsec vs am gear carb Mazda RX4 21.0 6 160 110 3.90 2.620 16.46 0 1 4 4 Mazda RX4 Wag 21.0 6 160 110 3.90 2.875 17.02 0 1 4 4 Datsun 710 22.8 4 108 93 3.85 2.320 18.61 1 1 4 1 Hornet 4 Drive 21.4 6 258 110 3.08 3.215 19.44 1 0 3 1 Hornet Sportabout 18.7 8 360 175 3.15 3.440 17.02 0 0 3 2 Valiant 18.1 6 225 105 2.76 3.460 20.22 1 0 3 1Examplemtcars_data_table
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