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This example demonstrate about How to resize Image in Android App.Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to res/layout/activity_main.xml. Step 3 − Add the following code to src/MainActivity.javapackage app.tutorialspoint.com.sample ; import android.app.Activity ; import android.content.Intent ; import android.graphics.Bitmap ; import android.net.Uri ; import android.provider.MediaStore ; import android.support.v7.app.AppCompatActivity ; import android.os.Bundle ; import android.view.View ; import android.widget.ImageView ; import java.io.IOException ; ... Read More
The main difference between require and library is that require was designed to use inside functions and library is used to load packages. If a package is not available then library throws an error on the other hand require gives a warning message.Using library> library(xyz) Error in library(xyz) : there is no package called ‘xyz’Using requirerequire(xyz) Loading required package: xyz Warning message: In library(package, lib.loc = lib.loc, character.only = TRUE, logical.return = TRUE, : there is no package called ‘xyz’Here we can see that the library shows an error and require gives a warning message, since warnings are mostly avoided ... Read More
The error “could not find function” occurs due to the following reasons −Function name is incorrect. Always remember that function names are case sensitive in R.The package that contains the function was not installed. We have to install packages in R once before using any function contained by them. It can be done as install.packages("package_name")The package was not loaded before using the function. To use the function that is contained in a package we need to load the package and it can be done as library("package_name").Version of R is older where the function you are using does not exist.If you ... Read More
An inner join return only the rows in which the left table have matching keys in the right table and an outer join returns all rows from both tables, join records from the left which have matching keys in the right table. This can be done by using merge function.ExampleInner Join> df1 = data.frame(CustomerId = c(1:5), Product = c(rep("Biscuit", 3), rep("Cream", 2))) > df1 CustomerId Product 1 1 Biscuit 2 2 Biscuit 3 3 Biscuit 4 4 Cream 5 5 Cream > df2 = data.frame(CustomerId = c(2, 5, 6), City = c(rep("Chicago", 2), rep("NewYorkCity", 1))) > df2 CustomerId City ... Read More
The use of set.seed is to make sure that we get the same results for randomization. If we randomly select some observations for any task in R or in any statistical software it results in different values all the time and this happens because of randomization. If we want to keep the values that are produced at first random selection then we can do this by storing them in an object after randomization or we can fix the randomization procedure so that we get the same results all the time.ExampleRandomization without set.seed> sample(1:10) [1] 4 10 5 3 1 6 ... Read More
This can be done by using list function.Example> df1
We can do this by using filter and grepl function of dplyr package.ExampleConsider the mtcars data set.> data(mtcars) > head(mtcars) 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 ... Read More
This can be done by using theme argument in ggplot2Example> df df x y 1 long text label a -0.8080940 2 long text label b 0.2164785 3 long text label c 0.4694148 4 long text label d 0.7878956 5 long text label e -0.1836776 6 long text label f 0.7916155 7 long text label g 1.3170755 8 long text label h 0.4002917 9 long text label i 0.6890988 10 long text label j 0.6077572Plot is created as follows −> library(ggplot2) > ggplot(df, aes(x=x, y=y)) + geom_point() + theme(text = element_text(size=20), axis.text.x = element_text(angle=90, hjust=1))
The easiest way to do it is by using select_if function of dplyr package but we can also do it through lapply.Using dplyr> df df X1 X2 X3 X4 X5 1 1 11 21 a k 2 2 12 22 b l 3 3 13 23 c m 4 4 14 24 d n 5 5 15 25 e o 6 6 16 26 f p 7 7 17 27 g q 8 8 18 28 h r 9 9 19 29 i s 10 10 20 30 j t >library("dplyr") > select_if(df, is.numeric) X1 X2 X3 1 1 11 21 2 2 12 22 3 3 13 23 4 4 14 24 5 5 15 25 6 6 16 26 7 7 17 27 8 8 18 28 9 9 19 29 10 10 20 30Using lapply> numeric_only df[ , numeric_only] X1 X2 X3 1 1 11 21 2 2 12 22 3 3 13 23 4 4 14 24 5 5 15 25 6 6 16 26 7 7 17 27 8 8 18 28 9 9 19 29 10 10 20 30
We can do this by setting the column to NULLExample> library(data.table) > df data_table data_table[, x:=NULL] > data_table numbers 1: 1 2: 2 3: 3 4: 4 5: 5 6: 6 7: 7 8: 8 9: 9 10: 10To delete two columns> df Data_table Data_table numbers 1: 0 2: 1 3: 2 4: 3 5: 4 6: 5 7: 6 8: 7 9: 8 10: 9