CODEWITHSUNDEEP
pythonpython-3.x
Anderson P
Anderson P

Reputation: 107

Entering floats into a list without overwriting list

I have some code here meant to allow me to keep creating floats until I input 0 to have it stop (the 0 is then deleted). These floats are supposed to be entered into a list. The issue I'm having is that each time the while loop is run, the float_list is overwritten. 

again = True
float_count = 1
while (again):
    float_list = [float(input("Float%d: " % i))for i in range(float_count, float_count + 1)]
    last_float = float_list[-1]
    if (last_float == 0):
        again = False
        del float_list[-1]
    else:
        float_count = float_count + 1

Is there any way to alter this code so all of the floats are entered into a list? Thanks!

Upvotes: 1

Views: 98

Answers (2)

AChampion
AChampion

Reputation: 30288

This maybe a good option to use the alternative form of iter(fn, sentinel), e.g.:

float_list = [float(x) for x in iter(input, '0')]

If you need the prompt then you can create a helper function:

import itertools as it

fc = it.count(1)
float_list = [float(x) for x in iter(lambda: input('Float{}: '.format(next(fc))), '0')]

Or alternatively (most closely matches OP's attempt - would exit on 0, 0.0, 0.00, etc.):

fc = it.count(1)
float_list = list(iter(lambda: float(input('Float{}: '.format(next(fc)))), 0.0))

With error handling:

def get_float():
    fc = it.count(1)
    def _inner():
        n = next(fc)
        while True:
            try:
                return float(input("Float{}: ".format(n)))
            except ValueError as e:
                print(e)
    return _inner

float_list = list(iter(get_float(), 0.0))

Upvotes: 2

thebjorn
thebjorn

Reputation: 27361

A list comprehension really isn't appropriate here. Much simpler:

float_count = 1
float_list = []
while True:
    val = input("Float%d: " % float_count)
    if val == '0':
        break
    float_list.append(float(val))  # call float(val) to convert from string to float
    float_count += 1

it might be more user friendly to not crash if the user didn't type a float, e.g.:

def read_float(msg):
    while 1:
        val = input(msg)
        if val == '0':
            return val
        try:
            return float(val)
        except ValueError:
            print("%s is not a float, please try again.." % val)

def read_float_list():
    float_count = 1
    float_list = []
    while True:
        val = read_float("Float%d: " % float_count)
        if val == '0':
            break
        float_list.append(val)  # now val has been converted to float by read_float.
        float_count += 1

Upvotes: 1

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