\(\renewcommand\AA{\unicode{x212B}}\)
% (modulo) operator to test if a number is a
multiple of another number. The answer is the remainder of the
division of the lhs into whole parts, e.g. 4 % 1 = 0, 4 % 2 = 0, 4 %
3 = 1, 4 % 4 = 0)# Write a program that prints out the square of the first
# 20 integers a block such that the block has a dimension of 4x5.
for i in range(1,21):
print(str(i*i).center(3),end=' ') # center is a function for strings that centers the contents to the given width
if i % 4 == 0:
print()
# ------------ Produces -------------
# 1 4 9 16
# 25 36 49 64
# 81 100 121 144
#169 196 225 256
#289 324 361 400
0,1 and next number is the sum
of the two previous numbers)# prev_2 - One before previous number
# prev_1 - Previous number
prev_2, prev_1 = 0, 1
# Already have first 2 terms above
print(prev_2)
print(prev_1)
# Now the next 23 terms (range(0,23) will run the loop 23 times)
for i in range(0,23):
current = prev_2 + prev_1
# Ratio to previous
ratio = float(current)/prev_1
print(str(current) + " ratio to previous= " +str(ratio))
# Move the previous markers along one for the next time around
prev_2 = prev_1
prev_1 = current
fib that accepts a number. The
function should compute a fibonacci sequence containing this many
elements and return them as a list.# Write a program that builds a list of the first 20 Fibonacci numbers, then
## Use the list to print out the value of the ratio of successive numbers of the sequence,
## printing out the final value.
## Extend the program so that the Fibonacci list is calculated in a function that takes the
## number of required values as a parameter and returns the list.
# Function to calculate the first n fibonacci numbers
# and return them as a list
def fib(nfibs):
if nfibs == 0:
return []
elif nfibs == 1:
return [0]
else:
pass
# First two numbers
fibs = [0,1]
if nfibs == 2:
return fibs
for i in range(2, nfibs):
fibs.append(fibs[i-2] + fibs[i-1])
return fibs
#### fib ends here ####
# Print out successive ratio remembering that the first number is a zero
nfibs = 20
fib_nums = fib(nfibs)
for i in range(1,nfibs):
try:
numerator = fib_nums[i]
denominator = fib_nums[i-1]
ratio = float(numerator)/denominator
except ZeroDivisionError:
print('Warning: Invalid ratio: ' + str(numerator) + '/' + str(denominator))
else:
print('Ratio ' + str(numerator) + '/' + str(denominator) + ': ' + str(ratio))
##### Produces #####
#Warning: Invalid ratio: 1/0
#Ratio 1/1: 1.0
#Ratio 2/1: 2.0
#Ratio 3/2: 1.5
#Ratio 5/3: 1.66666666667
#Ratio 8/5: 1.6
#Ratio 13/8: 1.625
#Ratio 21/13: 1.61538461538
#Ratio 34/21: 1.61904761905
#Ratio 55/34: 1.61764705882
#Ratio 89/55: 1.61818181818
#Ratio 144/89: 1.61797752809
#Ratio 233/144: 1.61805555556
#Ratio 377/233: 1.61802575107
#Ratio 610/377: 1.61803713528
#Ratio 987/610: 1.61803278689
#Ratio 1597/987: 1.61803444782
#Ratio 2584/1597: 1.6180338134
#Ratio 4181/2584: 1.61803405573
# Write a program that creates a dictionary and initializes it with 5 names/ID pairs.
## Create a function that prints out the dictionary in a nicely formatted table;
## Update the dictionary with another 5 name/values and reprint the table,
## making sure you understand the ordering within the map.
def formatLine(cola, colb, width):
return cola.center(width) + '|' + colb.center(width)
# A simple two cloumn print out
def outputStore(store):
print('Phonebook contains {} entries:'.format(len(store)))
# Do a quick sweep to find out the longest name
col_width = 0
for k in store:
if len(k) > col_width:
col_width = len(k)
col_width += 5
# Header
print('-'*col_width*2)
print(formatLine('Name', 'Ext.', col_width))
print('-'*col_width*2)
for k ,v in store.items():
print(formatLine(k, str(v), col_width))
phone_book = {'Martyn Gigg' : 1234, 'Joe Bloggs' : 1233, 'Guido Van Rossum' : 4321, 'Bob' : 2314, 'Linus Torvalds' : 4132 }
outputStore(phone_book)
# Update Dictionary (replacing one person's phone number
new_entries = {'Bjarne Strousoup' : 9876, 'Bill Gates' : 9898, 'Steve Jobs' : 7898, \
'Bob' : 9871, 'Dave' : 7098 }
phone_book.update(new_entries)
outputStore(phone_book)
#------------- Produces --------------------
#Phonebook contains 5 entries:
#------------------------------------------
# Name | Ext.
#------------------------------------------
# Bob | 2314
# Joe Bloggs | 1233
# Linus Torvalds | 4132
# Guido Van Rossum | 4321
# Martyn Gigg | 1234
#Phonebook contains 9 entries:
#------------------------------------------
# Name | Ext.
#------------------------------------------
# Guido Van Rossum | 4321
# Martyn Gigg | 1234
# Steve Jobs | 7898
# Bjarne Strousoup | 9876
# Joe Bloggs | 1233
# Linus Torvalds | 4132
# Dave | 7098
# Bill Gates | 9898
# Bob | 9871
.split() function that splits the string on whitespace and
gives back a list with each section as an element of the list)## Exercise 5
# 1. Build a list containing the 5 filenames of the text files that are going to be used.
# (Hint: Can be done by hand or using the os.listdir() function in the os module)
# 2. Add a bogus file name that doesn't exist to the list (so that we have to do some error handling)
# 3. Loop over the list and for each file (Remember here that we have a non existent file in the list and calling open
# on this will result in an IOError exception that needs to be dealt with)
# 1. Open the file;
# 2. Loop over each line;
# 3. Split the line up into sections (Hint: The string has a .split() function that splits the string on
# whitespace and gives back a list with each section as an element of the list)
# 4. Convert the second column value into an integer
# 5. Keep track of the values for each line and compute an average for the file.
# 4. Finally, print out a list of file,average-value pairs
import os
file_dir = "C:\\MantidInstall\\data\\"
file_names = os.listdir(file_dir)
file_names.append('nonexistant.txt')
average_store = {}
print('Computing average for log files in directory "' + file_dir + '"')
for name in file_names:
# Skip all no text files
if name.endswith('.txt') == False:
continue
try:
file_handle = open(os.path.join(file_dir,name), 'r')
except IOError:
print('\tError: No such file: "' + name + '". Skipping file')
continue
print('\tReading file',name)
# At this point we have an open file
average = 0.0
nvalues = 0
line_counter = 1
for line in file_handle:
columns = line.split()
if len(columns) == 2:
average += float(columns[1])
nvalues += 1
else:
print('\tWarning: Unexpected file format encountered in file {0} on line {1}'.format(name,line_counter))
line_counter += 1
average /= nvalues
average_store[name] = average
file_handle.close()
# Print out file averages
column_width = 30
print('')
print('-'*column_width*2)
print('File'.center(column_width) + '|' + 'Average'.center(column_width))
print('-'*column_width*2)
for key, value in average_store.iteritems():
print(key.center(column_width) + '|' + str(value).center(column_width))