Question

http://www.un.org/Depts/DGACM/index_russian.htm

Ordinates for Probability Plotting

Description:

     Generates the sequence of probability points ‘(1:m - a)/(m +
     (1-a)-a)’ where ‘m’ is either ‘n’, if ‘length(n)==1’, or
     ‘length(n)’.

Usage:

     ppoints(n, a = ifelse(n <= 10, 3/8, 1/2))
...

我曾试图在<代码>python上复制这一功能,我有两点怀疑。

1- The first m in (1:m - a)/(m + (1-a)-a) is persistent an integer: int(n) (e:the integer of >?

2- The second m in the sameality is NOT an integer if length (n)==1 (它承担<代码>n和 a integer (length(n))其他用途。

3- The n in a = 如果else(n <= 10, 3/8, 1/2) is the real number n if length(n)==1 and the integer >codelength(n) otherwise.

描述中根本没有阐明这一点,我非常赞赏有人能够证实情况确实如此。

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最初张贴在https://stats.stackchange.com/。因为我希望得到与<代码>ppoints功能有关的静态人员的投入。自我迁出后,我写到以下职能之后,复制了<代码>ppoints,载于python。我对此进行了测试,而且这两种结果似乎都回过头来,但如果有人能够澄清上述要点,因为职能说明根本不明确。

def ppoints(vector): Mimics R s function ppoints . m_range = int(vector[0]) if len(vector)==1 else len(vector) n = vector[0] if len(vector)==1 else len(vector) a = 3./8. if n <= 10 else 1./2 m_value = n if len(vector)==1 else m_range pp_list = [((m+1)-a)/(m_value+(1-a)-a) for m in range(m_range)] return pp_list

Answer 1

我将怀着:壮志执行:

import numpy as np
def ppoints(n, a):
    """ numpy analogue or `R` s `ppoints` function
        see details at http://stat.ethz.ch/R-manual/R-patched/library/stats/html/ppoints.html 
        :param n: array type or number"""
    try:
        n = np.float(len(n))
    except TypeError:
        n = np.float(n)
    return (np.arange(n) + 1 - a)/(n + 1 - 2*a)

样本产出:

>>> ppoints(5, 1./2)
array([ 0.1,  0.3,  0.5,  0.7,  0.9])
>>> ppoints(5, 1./4)
array([ 0.13636364,  0.31818182,  0.5       ,  0.68181818,  0.86363636])
>>> n = 10
>>> a = 3./8. if n <= 10 else 1./2
>>> ppoints(n, a)
array([ 0.06097561,  0.15853659,  0.25609756,  0.35365854,  0.45121951,
        0.54878049,  0.64634146,  0.74390244,  0.84146341,  0.93902439])

人们可以使用用于测试实施情况。

Answer 2

R 帮助指(测试):

ppoints <- function(n) {
  if (is.array(n)) {
    m <- as.numeric(length(n))
  } else {
    m <- as.numeric(n)
  }
  a = if (m <= 10) 3/8 else 1/2
  return((seq_len(m)  - a) / (m + 1 - 2*a))
}

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