ctrlchrt.py

Created on September 08, 2025
1.05 KB
X-Bar and R Control Chart
Source: HP 65 Stat Pac 2, 1975
from math import *
# control chart function
# run as a defined function
# HP 65 Stat Pac 2, 1975


def ctrlchart():
  #elements
  a2=[0,0,1.88,1.02,.73,.58,.48,.42,.37,.34,.31,.29,.27,.25,.24,.22,.21,.20,.19,.19,.18]
  d3=[0,0,0,0,0,0,0,.08,.14,.18,.22,.26,.28,.31,.33,.35,.36,.38,.39,.4,.41]
  d4=[0,0,3.27,2.57,2.28,2.11,2,1.92,1.86,1.82,1.78,1.74,1.72,1.69,1.67,1.65,1.64,1.62,1.61,1.6,1.59]
  # calculation
  meansum=0
  rangesum=0
  n=int(input("number of samples? "))
  m=int(input("sample size (2-20)? "))
  for i in range(n):
    x=[]
    for j in range(m):
      # adjust to show proper numbering
      s="x("+str(i+1)+","+str(j+1)+")? "
      p=eval(input(s))
      x.append(p)
    rangesum+=max(x)-min(x)
    meansum+=sum(x)/m
  rangeavg=rangesum/n
  meanavg=meansum/n
  lowmean=meanavg-rangeavg*a2[m]
  highmean=meanavg+rangeavg*a2[m]
  lowrange=d3[m]*rangeavg
  highrange=d4[m]*rangeavg
  print("x-bar chart")
  print("L: "+str(lowmean))
  print("H: "+str(highmean))
  print("range chart")
  print("L: "+str(lowrange))
  print("H: "+str(highrange))