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FMDA Excercise 4.2

a guest Oct 13th, 2017 98 Never
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  1. #%% Exercise on population 4_2
  2. """
  3. Assignment:
  4.    1  download file
  5.    2  calculate pop change P[d] 'Population delta'
  6.    3  calculate pop growth rate 'r' in % on yearly basis (see calculation below)
  7.       r = P[d] / ( P[t-1] * t[d] )
  8.    4a print a table; headers & data
  9.    4b print a sequence of lines that read;
  10.       - Time period (initial year (t0) – final year (t1)).
  11.       - Initial population (million) at t0.
  12.       - Population change (million) <-- your results.
  13.       - Population growth rate (%) <-- your results.
  14. """
  15.  
  16. file_name = "your file name.dat"
  17. file_path1 = "your file path"
  18. file_path2 = "your alternative file path"
  19. file_path_complete1 = file_path1 + file_name
  20. file_path_complete2 = file_path2 + file_name
  21.  
  22.  
  23. line_data = 0 # emty this string before starting
  24. tab_char = 0 # location of tab
  25. prev_line_read = str() # empty string befrore starting
  26. pop_list = [] # list of population
  27. year_list = [] # list of year
  28. pop_incr = 0 # population increase per timestep
  29. a = 0 # iteration value for making lists (used multiple times)
  30. p_incr_list = [] # list of population increase per timestep
  31. growth_rate = 0 # speaks for itself
  32. r_list = [] # list of growthrates
  33.  
  34.  
  35.  
  36. #open file
  37. try:
  38.     file_data = open(file_path_complete1, "r")
  39. except:
  40.     try:
  41.         file_data = open(file_path_complete2, "r")
  42.     except:
  43.         print("Open Failed!")
  44.  
  45. # read data into list of population and year (and close file)
  46. while True:
  47.     line_read = file_data.readline()
  48.     try: # Check if line is data or something else (header or end)
  49.         line_data = int(line_read[:1]) + 1
  50.         tab_char = line_read.find("\t", 1)
  51.         line_read_len = len(line_read) - 1
  52.        
  53.         population = int(line_read[tab_char + 1:line_read_len])
  54.         pop_list.append(population)
  55.         year = int(line_read[:tab_char])
  56.         year_list.append(year)
  57.     except:
  58.         if line_read == "":
  59.             break
  60. file_data.close()
  61.  
  62. # print lists as check
  63. #print(year_list, "\n")
  64. #print(pop_list, "\n")
  65.  
  66. #(step 2) make list of population increase per timestep
  67. for i in pop_list:
  68.     if a != 0:
  69.         b = a - 1
  70.         pop_incr = (pop_list[a]) - (pop_list[b])
  71.         p_incr_list.append(pop_incr)
  72.     else:
  73.         p_incr_list.append(0)
  74.     a = a + 1
  75.  
  76. # print list as check
  77. #print(p_incr_list, "\n")
  78.  
  79. #(step 3) calculate growthrate 'r'
  80. a = 0
  81. for i in pop_list:
  82.     if a != 0:
  83.         b = a - 1
  84.         growth_rate = p_incr_list[a] / ( pop_list[b] * ( year_list[a] - year_list[b] ) )
  85.         growth_rate = round(growth_rate, 4)
  86.         r_list.append(growth_rate)
  87.     else:
  88.         r_list.append(0)
  89.     a = a + 1
  90.  
  91. # print list as check
  92. #print(r_list, "\n")
  93.  
  94. #(step 4a) print a table
  95. print("Year\tPopulation\tPop. increase\tGrowth rate")
  96. a = 0
  97. for i in pop_list:
  98.     print(year_list[a], "\t", pop_list[a], "\t", p_incr_list[a], "\t", r_list[a])
  99.     a = a + 1
  100.  
  101. #(step 4b) print line sequence
  102. print("\n- Time period ", year_list[0], " to ", year_list[len(year_list)-1])
  103. population = round(float(pop_list[0])/1000,1)
  104. print("- Initial population", population, " (million) at year ", year_list[0])
  105. pop_change = round(float((pop_list[len(pop_list)-1] - pop_list[0]))/1000, 1)
  106. print("- Population change ", pop_change, " (million)")
  107. growth_rate = round(float( sum(p_incr_list) / ( pop_list[0] * ( year_list[len(year_list)-1] - year_list[0] ) ))*100,2)
  108. print("- Population growth rate ", growth_rate, "% (yearly average)")
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