Hypertechblog

Rational Number or Rational Mothod in ruby or Rational operation Rational Number is always comes with paired integer Number(1 ,2 ,3 .... && -1, -2, .....) x/y (where y>0). Rational (1) => (1/1) Rational (2, 5) =>(2/5) Rational(4, -8) => (-1/2) 5.to_r =>(5/1) 2/3r => (2/3) Rational into Numeric rational*numeric -> numeric (perfoms multiplecation) Rational(1, 3)  * Rational(2, 3)   => (2/9) Rational(200)   * Rational(1)      => (200/1) Rational(-5, 4) * Rational(-4, 5)  => (1/1) Rational(9, 4)  * 4                => (9/1) Rational(20, 9) * 9.8              => 21.77777777777778 rat ** numeric => numeric (Performs exponentiation) Rational(3)    ** Rational(3)    => (27/1) Rational(10)   ** -2             => (1/100) Rational(10)   ** -2.0           => 0.01 Rational(-4)   ** Rational(1,2)  => (1.2246063538223773e-16+2.0i) Rational(1, 2) ** 0              => (1/1) Rational(2,

Difference Between select and collect Select & collect select return array of hash of all field into a table Example user.select(:id) // it will return all fields with id user.all.collect(&:id) // it will array of id's

Difference Between pluck and collect Pluck Pluck takes less time then collect because when we use collect we have to execute two queries for collecting record Example-  When have a user table and we have to collect all id's User.all.collect(&:id) // when we use collect we are running two query internally                                        first user.all and then we collect id's User.pluck(:id) // Here we are running only one query that's why it take less time Pluck also take more than one parameter at a time but collect can not Example- user.pluck(:id, :name) // it will return array of id and name user.collect(&:id , &:name) // it will give an error