Hướng dẫn python exponential distribution
Hàm exp(x) trong Python trả về ex. Nội dung chính Nội dung chính
Cú phápCú pháp của exp() trong Python: Ghi chú: Hàm này không có thể truy cập trực tiếp, vì thế chúng ta cần import math module và sau đó chúng ta cần gọi hàm này bởi sử dụng đối tượng math. Các tham số:
Ví dụ sau minh họa cách sử dụng của hàm exp() trong Python. import math print ("math.exp(-45) : ", math.exp(-45)) print ("math.exp(10.15) : ", math.exp(10.15)) print ("math.exp(100) : ", math.exp(100)) print ("math.exp(math.pi) : ", math.exp(math.pi)) Chạy chương trình Python trên sẽ cho kết quả: math.exp(-45) : 2.8625185805493937e-20 math.exp(10.15) : 25591.102206689702 math.exp(100) : 2.6881171418161356e+43 math.exp(math.pi) : 23.140692632779267 The exponential distribution is a probability distribution that is used to model the time we must wait until a certain event occurs. If a random variable X follows an exponential distribution, then the cumulative distribution function of X can be written as: F(x; λ) = 1 – e-λx where:
This tutorial explains how to use the exponential distribution in Python. How to Generate an Exponential DistributionYou can use the expon.rvs(scale, size) function from the SciPy library in Python to generate random values from an exponential distribution with a specific rate parameter and sample size: from scipy.stats import expon #generate random values from exponential distribution with rate=40 and sample size=10 expon.rvs(scale=40, size=10) array([116.5368323 , 67.23514699, 12.00399043, 40.74580584, 34.60922432, 2.68266663, 22.70459831, 97.66661811, 6.64272914, 46.15547298]) Note: You can find the complete documentation for the SciPy library here. How to Calculate Probabilities Using an Exponential DistributionSuppose the mean number of minutes between eruptions for a certain geyser is 40 minutes. What is the probability that we’ll have to wait less than 50 minutes for an eruption? To solve this, we need to first calculate the rate parameter:
We can plug in λ = .025 and x = 50 to the formula for the CDF:
The probability that we’ll have to wait less than 50 minutes for the next eruption is 0.7135. We can use the expon.cdf() function from SciPy to solve this problem in Python: from scipy.stats import expon #calculate probability that x is less than 50 when mean rate is 40 expon.cdf(x=50, scale=40) 0.7134952031398099 The probability that we’ll have to wait less than 50 minutes for the next eruption is 0.7135. This matches the value that we calculated by hand. How to Plot an Exponential DistributionYou can use the following syntax to plot an exponential distribution with a given rate parameter: from scipy.stats import expon import matplotlib.pyplot as plt #generate exponential distribution with sample size 10000 x = expon.rvs(scale=40, size=10000) #create plot of exponential distribution plt.hist(x, density=True, edgecolor='black') Additional ResourcesThe following tutorials explain how to use other common distributions in Python: How to Use the Poisson Distribution in Python Draw samples from an exponential distribution. Nội dung chính
Its probability density function is \[f(x; \frac{1}{\beta}) = \frac{1}{\beta} \exp(-\frac{x}{\beta}),\] for The exponential distribution is a continuous analogue of the geometric distribution. It describes many common situations, such as the size of raindrops measured over many rainstorms [1], or the time between page requests to Wikipedia [2]. Note New code should use the The scale parameter, \(\beta = 1/\lambda\). Must be non-negative. sizeint or tuple of ints, optionalOutput shape. If the given shape is, e.g., Drawn samples from the parameterized exponential distribution. References 1Peyton Z. Peebles Jr., “Probability, Random Variables and Random Signal Principles”, 4th ed, 2001, p. 57. 2Wikipedia, “Poisson process”, https://en.wikipedia.org/wiki/Poisson_process Wikipedia, “Exponential distribution”, https://en.wikipedia.org/wiki/Exponential_distribution I think you are actually asking about a regression problem, which is what Praveen was suggesting. You have a bog standard exponential decay that arrives at the y-axis at about y=0.27. Its equation is therefore
Here's the plot. Notice that I save the output values for subsequent use. Now I can calculate the nonlinear
regression of the exponential decay values, contaminated with noise, on the independent variable, which is what
The bonus is that, not only does Here's how to calculate the residuals. Notice that each residual is the
difference between the data value and the value estimated from
If you wanted to further 'test that my function is indeed going through the data points' then I would suggest looking for patterns in the residuals. But discussions like this might be beyond what's welcomed on stackoverflow: Q-Q and P-P plots, plots of residuals vs View Discussion Improve Article Save Article View Discussion Improve Article Save Article With the help of numpy.random.exponential() method, we can get the random samples from exponential distribution and returns the numpy array of random samples by using this method. exponential distribution
Example #1 : In this example we can see that by using numpy.random.exponential() method, we are able to get the random samples of exponential distribution and return the samples of numpy array. Python3
Output : Example #2 : Python3
Output : How do you generate a random number from exponential distribution in Python?exponential() in Python. With the help of numpy. random. exponential() method, we can get the random samples from exponential distribution and returns the numpy array of random samples by using this method. How do you generate a random number from an exponential distribution?So, one strategy we might use to generate a 1000 numbers following an exponential distribution with a mean of 5 is:. Generate a Y ∼ U ( 0 , 1 ) random number. ... . Then, use the inverse of Y = F ( x ) to get a random number X = F − 1 ( y ) whose distribution function is . ... . Repeat steps 1 and 2 one thousand times.. What is scale in Numpy random exponential?numpy.random.exponential(scale=1.0, size=None) Exponential distribution. Its probability density function is. for x > 0 and 0 elsewhere. is the scale parameter, which is the inverse of the rate parameter. How do you fit an exponential distribution in Python?The solution is to fit using an exponential function where `b` is constrained to 0 (or whatever value you know it to be). ```python def monoExpZeroB(x, m, t): return m * np. exp(-t * x) # perform the fit using the function where B is 0 p0 = (2000, . 1) # start with values near those we expect paramsB, cv = scipy. |