[英]Why isnt the indexing in this python script working?
我正在為一項任務編寫此腳本,因此我希望通過它進行交談,而不是簡單地得到答案。 基本上我試圖將英尺轉換為米,米轉換為英尺,並在最后提供兩者的總轉換距離之和。 沒有 [] 索引,它工作得很好。 我剛剛添加並正在努力解決的新部分是 [] 索引,老實說,我正在研究它們是如何工作的。 無論如何繼承代碼:
MAX = 256
switch = ""
feet = [0.0] * MAX
meters = [0.0] * MAX
feetpermeter = 3.28084
metersperfoot = 0.3048
sum_meters = 0
sum_feet = 0
def main():
selector()
def selector():
while True:
print("Is your measurement in meters or feet?")
switch = input("Or would you like to quit?")
if (switch == "feet" or switch == "Feet"):
ftm()
elif (switch == "meters" or switch == "Meters"):
mtf()
elif (switch == "quit" or switch == "Quit"):
end()
else:
print("Sorry, that wasn't one of the options.")
print("Lets try that again")
def mtf():
try:
meters[sum_meters] = float(input("Enter the number of meters. "))
feet[sum_feet] = meters * feetpermeter
print("That is", feet, "feet.")
main()
except:
print("Sorry, I didn't quite get that, lets try again.")
mtf()
def ftm():
try:
feet[sum_feet] = float(input("Enter the number of feet. "))
meters[sum_meters] = feet * metersperfoot
print("That is", meters, "meters.")
main()
except:
print("Sorry, I didn't quite get that, lets try again.")
ftm()
def end():
while True:
switch2 = input("Are you sure you want to quit(y/n)?")
if (switch2 == "y" or switch2 == "Y"):
print("you converted a total of ", sum(feet), "feet")
print("And", sum(meters), "meters.")
print("Bye!")
exit()
elif (switch2 == "n" or switch2 == "N"):
print("Ok, let's try that again.")
main()
else:
print("Sorry, that wasn't one of the options.")
print("Lets try that again")
main()
我確實嘗試在每個結果之后使用 sum_feet + 1 和 sum_meters + 1 ,但這也沒有奏效。
您沒有以正確的方式使用索引。 例如,查看現有代碼的注釋:
def mtf():
try:
# Error 1. You stored all the inputs to index 0, as sum_meters is 0 always and its not incremented
# So, all the inputs are not recorded, only last one gets in index 0
meters[sum_meters] = float(input("Enter the number of meters. "))
# Error 2: You multiplied the whole list against the conversion parameter.
# Instead, you should multiply the value at current index
feet[sum_feet] = meters * feetpermeter
# This will print the whole list. Again use the current index here
print("That is", feet, "feet.")
main()
except:
print("Sorry, I didn't quite get that, lets try again.")
mtf()
function 的固定版本如下:
def mtf():
try:
# For modifying global variables in a function scope
global sum_meters
global sum_feet
meters[sum_meters] = float(input("Enter the number of meters. "))
feet[sum_feet] = meters[sum_meters] * feetpermeter
print(f"That is {feet[sum_feet]} feet.")
sum_meters += 1
sum_feet += 1
main()
except:
print("Sorry, I didn't quite get that, lets try again.")
mtf()
此修復程序也適用於您的其他功能。 我還想給您另一條建議,您可以使用面向此類問題的良好 object 方法,這樣可以更輕松地實現。 你可以從中學到很多東西,然后你會更有信心。
作為示例,請參見下面的代碼 - 幾乎相同,但方式更清晰。
class Converter:
FEET_PER_METER = 3.28084
METERS_PER_FOOT = 0.3048
def __init__(self):
self.feet_store = []
self.meter_store = []
self.curr_index = 0
self.menu_handlers = {
"feet": self.feet_to_meter,
"meters": self.meter_to_feet,
"quit": self.summary
}
def run_selection(self, selected):
#
selected = str.lower(selected)
if selected in self.menu_handlers:
# call the relevant function
return self.menu_handlers.get(selected)()
return False
def meter_to_feet(self):
meters_in = float(input("Enter the number of meters."))
to_feet = meters_in * self.FEET_PER_METER
self.meter_store.append(meters_in)
self.feet_store.append(to_feet)
print(f"In Feet : {to_feet}")
return to_feet
def feet_to_meter(self):
feet_in = float(input("Enter the number of feet."))
to_meters = feet_in * self.METERS_PER_FOOT
self.feet_store.append(feet_in)
self.meter_store.append(to_meters)
print(f"In Meters : {to_meters}")
return to_meters
def summary(self):
confirm = input("Are you sure you want to quit(y/n)?")
if confirm in ["y", "Y"]:
print("you converted a total of ", sum(self.feet_store), "feet")
print("And", sum(self.meter_store), "meters.")
print("Bye!")
exit()
else:
return False
def main():
converter = Converter()
while True:
choice = input("Is your measurement in meters or feet (meters/feet/quit)?")
converter.run_selection(choice)
我希望這能給你更好的見解。
因此,您在這里嘗試執行的操作存在兩個問題:
meters[sum_meters] = float(input("Enter the number of meters. "))
feet[sum_feet] = meters * feetpermeter
米 * 英尺每米是一個數組乘以一個數字,你需要做米[sum_meters] 來得到你想要的數字。 其次,正如您所說,您需要每次增加 sum_meters ,但是因為您在 function 中,您需要在更改之前將變量聲明為全局變量。 此外,由於 sum_meters 和 sum_feet 總是相等的,您可以只使用一個變量來跟蹤這一點:
def mtf():
try:
global index
meters[index] = float(input("Enter the number of meters. "))
feet[index] = meters[index] * feetpermeter
index += 1
print("That is", feet, "feet.")
main()
except:
print("Sorry, I didn't quite get that, lets try again.")
mtf()
def ftm():
try:
global index
feet[index] = float(input("Enter the number of feet. "))
meters[index] = feet * metersperfoot
index += 1
print("That is", meters, "meters.")
main()
except:
print("Sorry, I didn't quite get that, lets try again.")
ftm()
我還想進一步說 go 並說對於這個問題不需要使用列表,你可以簡單地有兩個數字,total_meters 和 total_feet,然后像 go 一樣添加值。 這將花費更少的 memory 並消除已施加的 256 次任意限制。 所以我會這樣做:
import sys
MAX = 256
switch = ""
total_feet = 0
total_meters = 0
feetpermeter = 3.28084
metersperfoot = 0.3048
sum_meters = 0
sum_feet = 0
index = 0
def main():
selector()
def selector():
while True:
print("Is your measurement in meters or feet?")
switch = input("Or would you like to quit?")
if switch == "feet" or switch == "Feet":
ftm()
elif switch == "meters" or switch == "Meters":
mtf()
elif switch == "quit" or switch == "Quit":
end()
sys.exit(0)
else:
print("Sorry, that wasn't one of the options.")
print("Lets try that again")
def mtf():
try:
global total_feet
global total_meters
meters = float(input("Enter the number of meters. "))
feet = meters * feetpermeter
total_meters += meters
total_feet += feet
print("That is", feet, "feet.")
main()
except Exception as e:
print(e)
print("Sorry, I didn't quite get that, lets try again.")
mtf()
def ftm():
try:
global total_feet
global total_meters
feet = float(input("Enter the number of feet. "))
meters = feet * metersperfoot
total_meters += meters
total_feet += feet
print("That is", meters, "meters.")
main()
except Exception as e:
print(e)
print("Sorry, I didn't quite get that, lets try again.")
ftm()
def end():
while True:
switch2 = input("Are you sure you want to quit(y/n)?")
if switch2 == "y" or switch2 == "Y":
print("you converted a total of ", total_feet, "feet")
print("And", total_meters, "meters.")
print("Bye!")
exit()
elif switch2 == "n" or switch2 == "N":
print("Ok, let's try that again.")
main()
else:
print("Sorry, that wasn't one of the options.")
print("Lets try that again")
main()
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