Python code to take user input and execute functions from that input

Question

I have multiple functions in order like below:

  test1func()
  test2func()
  test3func()
  test4func()
  test5func()
  test6func()

I want to develop a logic which asks the user to input the number, from where the program will executing the functions.

For example if user selects 3 then it should start from function test3func() to test6func() if he selects 5 then test5() then from test5func() to test6func().

Trial code:

 print "1).fun1\n2).fun2\n3).fun3\n4).fun4\n5).fun5\n6).fun6"
 select_fun = raw_input"Choose from which function it has to start"

How can I achieve above requirement?

Check out [dictionary mappings](https://stackoverflow.com/a/11479840/7443472) — Secespitus, Jun 27 '17 at 13:55
you could use if statements here. `if input == something then function` — MattR, Jun 27 '17 at 13:56
Possible duplicate of [What is the Python equivalent for a case/switch statement?](https://stackoverflow.com/questions/11479816/what-is-the-python-equivalent-for-a-case-switch-statement) — Secespitus, Jun 27 '17 at 13:57

Maxim Krabov · Answer 1 · 2017-06-27T14:43:33.770

3

def t1():
    print(1)

def t2():
    print(2)

def t3():
    print(3)

def t4():
    print(4)

def t5():
    print(5)

def t6():
    print(6)

# put the functions in a list
functions = [t1, t2, t3, t4, t5, t6]

def go(functions):
    # .format(variable) replaces {} with the value of variable (string formatting)
    number_of_funcs = len(functions)
    greeting = "Type a number from 1 to {}: ".format(number_of_funcs)
    selected = input(greeting)
    try:
        # index to start from
        index = int(selected) - 1
    except ValueError:
        # check if the user wrote a number (exception handling)
        print('Invalid input. Not a number')
        return
    if index > number_of_funcs - 1 or index < 0:
        msg = 'Invalid input. Consider a number from 1 to {}'.format(number_of_funcs)
        print(msg)
        return
    # iterate through the functions of the list
    # starting from the index specified (list slicing)
    for f in functions[index:]:
        f()

while(True):
    # infinite loop. press Ctrl+C to abort
    go(functions)

See also

exception handling

string formatting

list slicing

edited Jun 27 '17 at 14:43

answered Jun 27 '17 at 14:16

Maxim Krabov

685
5
17

What's with `while(True): go(functions)`? – Brett Beatty Jun 27 '17 at 14:18
@BrettBeatty this will continue asking your for input even if you put incorrect one. Press Ctrl+C to abort – Maxim Krabov Jun 27 '17 at 14:19
I feel like the better answer for that would be recursion. If the input is invalid, just do `return go(functions)` instead of `return`. Then it will keep going until it gets valid input, and the user doesn't have to worry about pressing ctrl+C. – Brett Beatty Jun 27 '17 at 14:21
1

you should use a dynamic upper limit in the error message, ie `print('Invalid input. Consider a number from 1 to {}'.format(len(functions)))` – bruno desthuilliers Jun 27 '17 at 14:22
@BrettBeatty if one wouldn't like to the test code and try different inputs, your solution is better. – Maxim Krabov Jun 27 '17 at 14:24
@brunodesthuilliers agreed – Maxim Krabov Jun 27 '17 at 14:29

gboffi · Answer 2 · 2017-06-27T14:47:31.903

You can put all your functions in a list and call sequentially all the functions that are contained in a slice of the list, as in this toy example

In [11]: l_of_functions = [ lambda x=x: print(x) for x in range(10)]

In [12]: for fun in l_of_functions[5:]: fun()
5
6
7
8
9

In [13]: for fun in l_of_functions[0:]: fun()

0
1
2
3
4
5
6
7
8
9

In [14]:

Addendum

In case the OP needs a function to get a number from a closed interval, here it is my attempt

In [28]: def ask_inside(minimum, maximum, max_tries=10, this_try=0):
    ...:     answer = input('Give me a number comprised between %d and %d: '
    ...:                    %(minimum, maximum))
    ...:     try:
    ...:         number = int(answer)
    ...:     except ValueError:
    ...:         number = minimum-1
    ...:     if minimum <= number <= maximum: return number
    ...:     if this_try+1<max_tries:
    ...:         return ask(minimum, maximum,
    ...:                    max_tries=max_tries, this_try=this_try+1)
    ...:     else: print('You are boring')
    ...:     

In [29]: ask_inside(1, 6, max_tries=3)
Give me a number comprised between 1 and 6: 2
Out[29]: 2

In [30]: ask_inside(1, 6, max_tries=3)
Give me a number comprised between 1 and 6: ojig
Give me a number comprised between 1 and 6: 0 
Give me a number comprised between 1 and 6: 7
You are boring

In [31]:

Of course if you are on Python 2 print is a statement and input() → raw_input().

At least someone that bothered to read the full question... Congratulations ;) — bruno desthuilliers, Jun 27 '17 at 14:19

Archeo · Answer 3 · 2017-06-27T14:20:45.610

1

I suppose that you could build a dictionary :

functions = {
        1: test1func,
        2: test2func,
        3: test3func,
        4: test4func,
        5: test5func,
        6: test6func
    }

And then call the function whose key was received as input : functions[select_fun]().

Edit :

As commented below, I misunderstood the task to perform. To run all functions, from the one 'inputed' to the last, do so :

for i in range(select_fun, 7):
    functions[i]()

edited Jun 27 '17 at 14:20

answered Jun 27 '17 at 14:01

Archeo

221
1
6

2

My problem with this solution is that OP wants all subsequent functions to run, not just the one with the number the user supplied. – Brett Beatty Jun 27 '17 at 14:14
`for i in range(select_fun, 7): functions[i]()` – Archeo Jun 27 '17 at 14:16
1

@Archeo that will only run 1 function, not select_fun - > test6func – jambrothers Jun 27 '17 at 14:18

Alex Lucaci · Answer 4 · 2017-06-27T14:11:55.360

0

user_input = int(raw_input('Enter number')) # or int(input('Enter number')) for python3
for i in range (user_input,7):
     locals()["test"+str(i)+"function"]() #or  globals()["test"+i+"function"]()

Use locals if your functions are local or globals if there are global.

Use raw_input for python 2.x and input for python 3.x

edited Jun 27 '17 at 14:11

answered Jun 27 '17 at 14:06

Alex Lucaci

620
8
18

using `locals()` or `globals()` this way is considered bad style, in that it's not as explicit (and not as maintainable) as using a dedicated `dict` (or `list` or other container). Also it doesn't solve the OP's problem, please reread the question more carefully. – bruno desthuilliers Jun 27 '17 at 14:18

Python code to take user input and execute functions from that input

4 Answers4

Addendum