尝试使用R fitdistr {MASS}拟合伽马分布时出错 [英] Errors while trying to fit gamma distribution with R fitdistr{MASS}

问题描述

我在R中的fitdistr {MASS}函数有问题.我有这个向量:

I have a problem with fitdistr{MASS} function in R. I have this vector:

a <- c(26,73,84,115,123,132,159,207,240,241,254,268,272,282,300,302,329,346,359,367,375,378, 384,452,475,495,503,531,543,563,594,609,671,687,691,716,757,821,829,885,893,968,1053,1081,1083,1150,1205,1262,1270,1351,1385,1498,1546,1565,1635,1671,1706,1820,1829,1855,1873,1914,2030,2066,2240,2413,2421,2521,2586,2727,2797,2850,2989,3110,3166,3383,3443,3512,3515,3531,4068,4527,5006,5065,5481,6046,7003,7245,7477,8738,9197,16370,17605,25318,58524)

并且我想使用以下命令将伽马分布适合数据:

and I want to fit a gamma distribution to the data with a command:

fitted.gamma <- fitdistr(a, "gamma")

但是我有这样的错误:

Error in optim(x = c(26, 73, 84, 115, 123, 132, 159, 207, 240, 241, 254,  : 
non-finite finite-difference value [1]
In addition: Warning messages:
1: In densfun(x, parm[1], parm[2], ...) : NaNs produced
2: In densfun(x, parm[1], parm[2], ...) : NaNs produced
3: In densfun(x, parm[1], parm[2], ...) : NaNs produced
4: In densfun(x, parm[1], parm[2], ...) : NaNs produced

所以我尝试初始化参数:

So I tried with initializing the parameters:

(fitted.gamma <- fitdistr(a, "gamma", start=list(1,1)))

创建了fit.gamma对象，但在打印时会产生错误:

The object fitted.gamma is created but when printed, creates an error:

Error in dn[[2L]] : subscript out of bounds

您知道发生了什么吗，或者可能还知道其他一些R函数可以通过MLE拟合单变量分布?

Do you know what is happening or maybe know some other R functions to fit univariate distributions by MLE?

在此先感谢您的帮助或答复.

Thanks in advance for any help or response.

库巴

推荐答案

总是先绘制内容，缩放比例远远不够.

Always plot your stuff first, you scaling is far offfffffff.

library(MASS)
a <- c(26,73,84,115,123,132,159,207,240,241,254,268,272,282,300,302,329,346,359,367,375,378, 384,452,475,495,503,531,543,563,594,609,671,687,691,716,757,821,829,885,893,968,1053,1081,1083,1150,1205,1262,1270,1351,1385,1498,1546,1565,1635,1671,1706,1820,1829,1855,1873,1914,2030,2066,2240,2413,2421,2521,2586,2727,2797,2850,2989,3110,3166,3383,3443,3512,3515,3531,4068,4527,5006,5065,5481,6046,7003,7245,7477,8738,9197,16370,17605,25318,58524)
## Ooops, rater wide
plot(hist(a))
fitdistr(a/10000,"gamma") # gives warnings
# No warnings
fitted.gamma <- fitdistr(a/10000, dgamma,  start=list(shape = 1, rate = 0.1),lower=0.001)

现在您可以决定如何进行缩放

Now you can decide what to do with the scaling

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