Esempio: generazione di numeri casuali

Funzioni > Statistica > Distribuzioni di probabilità > Esempio: generazione di numeri casuali

Creare vettori di numeri casuali rispettivamente con distribuzione uniforme, distribuzione normale o distribuzione esponenziale in un intervallo.

Distribuzione uniforme

1. Chiamare la funzione runif per generare n_set numeri casuali distribuiti uniformemente tra numeri bassi e alti.

2. Utilizzare la funzione hist per generare un istogramma dell'insieme uniforme con n_bins barre e quindi calcolare la media dell'insieme.

3. Tracciare l'istogramma e mostrare la media prevista per l'insieme di dati:

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Per ottenere una nuova serie di numeri casuali, nel gruppo Controlli della scheda Calcolo fare clic su Calcola. Ogni volta che si esegue un nuovo calcolo, viene utilizzato un nuovo valore seed per generare numeri casuali.

Distribuzione normale

1. Chiamare la funzione rnorm per generare n_set numeri casuali con distribuzione normale, media μ e deviazione standard σ.

2. Utilizzare le funzioni floor, ceil, min e max per calcolare gli intervalli minimo e massimo dell'insieme di dati e quindi calcolare la larghezza di ogni barra:

3. Impostare la scala orizzontale per il grafico:

4. Chiamare la funzione dnorm per calcolare la distribuzione normale F prevista per l'insieme di dati e quindi tracciare un istogramma dell'insieme normale con n_bins barre.

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Distribuzione esponenziale

1. Chiamare la funzione rexp per generare un insieme di numeri casuali con distribuzione esponenziale con tasso r.

2. Chiamare la funzione dexp per calcolare la distribuzione esponenziale F prevista per l'insieme di dati e quindi tracciare un istogramma dell'insieme esponenziale con n_bins barre.

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3. Chiamare le funzioni pexp e qexp per calcolare rispettivamente la distribuzione cumulativa di probabilità per il valore x e la distribuzione cumulativa di probabilità inversa per il valore p e per tracciarne i grafici.

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Il primo argomento della funzione qexp è la probabilità e deve essere minore di 1, da cui la divisione di int per 100.

Argomenti correlati

Distribuzione uniforme

Distribuzione normale

Distribuzione esponenziale

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