The Gamma distribution in R Programming Language is defined as a two-parameter family of continuous probability distributions which is used in exponential distribution, Erlang distribution, and chi-squared distribution. This article is about the implementation of functions of the gamma distribution.
dgamma() Function
The dgamma() function is used to create a gamma density plot which is basically used due to exponential and normal distribution factors.
Syntax:
dgamma(x_dgamma, shape)
Parameters:
- x_dgamma: defines gamma function
- shape: gamma density of input values
- Returns: Plot dgamma values
Example :
# R program to plot gamma distribution # Specify x-values for gamma function x_dgamma <- seq (0, 2, by = 0.04)
# Apply dgamma function y_dgamma <- dgamma (x_dgamma, shape = 6)
# Plot dgamma values plot (y_dgamma)
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Output :
pgamma() Function
The pgamma() function is used in the cumulative distribution function (CDF) of the gamma distribution.
Syntax: pgamma(x_pgamma, shape)
Parameters:
- x_pgamma: defines gamma function
- shape: gamma density of input values
- Returns: Plot pgamma values
# Specify x-values for gamma function x_pgamma <- seq (0, 2, by = 0.04)
# Apply pgamma function y_pgamma <- pgamma (x_pgamma, shape = 6)
# Plot pgamma values plot (y_pgamma)
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Output:
qgamma() Function
It is known as the gamma quantile function of the gamma distribution and is used to plot qgamma distribution.
Syntax: qgamma(x_qgamma, shape)
Parameters:
- x_qgamma: defines gamma function
- shape: gamma density of input values
- Returns: Plot qgamma values with gamma density
# R program to plot gamma distribution # Specify x-values for gamma function x_qgamma <- seq (0, 1, by = 0.03)
# Apply qgamma function y_qgamma <- qgamma (x_qgamma, shape = 6)
# Plot qgamma values plot (y_qgamma)
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Output:
rgamma() Function
This function is basically used for generating random numbers in gamma distribution.
Syntax:
rgamma(N, shape)
Parameters:
- N: gamma distributed values
- shape: gamma density of input values
- Returns: Plot rgamma values with gamma density
# R program to plot gamma distribution # Set seed for reproducibility set.seed (1200)
# Specify sample size N <- 800 # Draw N gamma distributed values y_rgamma <- rgamma (N, shape = 5)
# Print values to RStudio console y_rgamma # Plot of randomly drawn gamma density hist (y_rgamma, breaks = 500,
main = "" )
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Output: