1. INPUT through functions - Rakhmanov

1. INPUT through functions

In [1]: C = input('C=?') C = float(C) F = (9./5)*C + 32 print (F)

C=?24 75.2

What is the difference between upper and lower program?

In [3]: C = float(input('C=?')) F = (9./5)*C + 32 print (F)

C=?24 75.2

EVAL function

In [6]: r = eval('1+2') r

Out[6]: 3

In [7]: a='1' b='2' c=eval(a+b) c

Out[7]: 12

In [8]: from math import sqrt r = eval('sqrt(2)') r

Out[8]: 1.4142135623730951

In [10]:

# Perimeter of Square def calculatePerimeter(l):

return 4*l

# Area of Square def calculateArea(l):

return l*l

expression = input("Type a function: ")

for l in range(1, 5): if (expression == 'calculatePerimeter(l)'): print("If length is ", l, ", Perimeter = ", eval(expression)) elif (expression == 'calculateArea(l)'): print("If length is ", l, ", Area = ", eval(expression)) else: print('Wrong Function') break

Type a function: calculateArea(l) If length is 1 , Area = 1 If length is 2 , Area = 4 If length is 3 , Area = 9 If length is 4 , Area = 16

EXEC

In [11]: program = 'a = 5\nb=10\nprint("Sum =", a+b)' exec(program)

Sum = 15

In [12]:

a = 5 b=10 print("Sum =", a+b)

Sum = 15

In [ ]:

program = input('Enter a program:') exec(program)

# [print(item) for item in [1, 2, 3]]

From String to code We need to install Scitools with: pip install scitools3

In [13]: from math import *

def f2(x): return exp(x)*sin(x)

In [14]: f2(2) Out[14]: 6.71884969742825

In [15]:

from scitools.StringFunction import StringFunction formula = 'exp(x)*sin(x)' f = StringFunction(formula)

# turn formula into function f(x)

In [16]: f(2) Out[16]: 6.71884969742825

2. Command line input

Cretae following programs and test through prompt

In [ ]:

# one input import sys C = float(sys.argv[1]) F = 9.0*C/5 + 32 print (F)

In [ ]:

import sys t = float(sys.argv[1]) v0 = float(sys.argv[2]) g = 9.81 y = v0*t - 0.5*g*t**2 print (y)

Error handling

In [18]:

C = float(input('Enter degree Celsium:')) F = 9.0*C/5 + 32 print (F)

Enter degree Celsium:5 41.0

In [19]:

try: C = float(input('Enter degree Celsium:'))

except: print ('You failed to provide Celsius degrees as input on the command line!') sys.exit(1) # abort

F = 9.0*C/5 + 32 print ('%gC is %.1fF' % (C, F))

Enter degree Celsium:we You failed to provide Celsius degrees as input on the command line!

---------------------------------------------------------------------------

ValueError

Traceback (most recent call last)

in

1 try:

----> 2

C = float(input('Enter degree Celsium:'))

3 except:

ValueError: could not convert string to float: 'we'

During handling of the above exception, another exception occurred:

NameError

Traceback (most recent call last)

in

3 except:

4

print ('You failed to provide Celsius degrees as input on the co

mmand line!')

----> 5

sys.exit(1) # abort

6

7 F = 9.0*C/5 + 32

NameError: name 'sys' is not defined

In [ ]:

try: C = float(input('Enter degree Celsium:'))

except IndexError: print ('Celsius degrees must be supplied on the command line') sys.exit(1) # abort execution

except ValueError: print ('Celsius degrees must be a pure number, not "%s"' % C) sys.exit(1)

F = 9.0*C/5 + 32 print ('%gC is %.1fF' % (C, F))

examples of Errors in python

In [23]:

data = [1.0/i for i in range(1,10)] data[we]

---------------------------------------------------------------------------

NameError

Traceback (most recent call last)

in

1 data = [1.0/i for i in range(1,10)]

----> 2 data[we]

NameError: name 'we' is not defined

In [24]: C = float('21 C')

---------------------------------------------------------------------------

ValueError

Traceback (most recent call last)

in

----> 1 C = float('21 C')

ValueError: could not convert string to float: '21 C'

In [25]:

forr d in data: return data

File "", line 1 forr d in data: ^

SyntaxError: invalid syntax

3. Interface

In [26]: import tkinter tkinter._test()

 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download