在 python 中将列表作为参数传递时出现未定义错误
undefined error when passing list as parameter in python
所以我之前设置了我的代码来访问一个在函数外部声明的列表，使其成为一个全局变量，对于分配给我的任务，讲师坚持我们不使用全局变量。所以现在我有以下代码，它显然给出了 "data_set undefined error"
我的想法是，我从一个 csv 文件创建一个列表，然后将该列表传递给其他几个函数，这样我就可以从 data_set 列表中获取元素并创建新的输出。
import csv
import sys
def print_menu():
print("ACME WEATHER DATA APP")
print("1) Choose weather data file")
print("2) See data for selected day")
print("3) Calculate average statistics for the data")
print("4) Print a scatterplot of the average temperatures")
print("0) Quit program")
def loadFile(x):
data_set = []
data_set.clear()
with open(x, "r") as readfile:
csv_reader = csv.reader(readfile, delimiter= ';')
for row in csv_reader:
data_set.append(row)
print("Loaded weather data from", (x[0:-4]).capitalize())
print()
return data_set
def avgDay(x, data_set):
for line in data_set:
if(len(x) == 5 and (x[3:5] + "-" + x[0:2]) in line[0]):
print("The weather on", x, "was on average", line[2], "centigrade")
def lowHigh(x, data_set):
for line in data_set:
if(len(x) == 5 and (x[3:5] + "-" + x[0:2]) in line[0]):
print("The lowest temperature was", line[3], "and the highest temperature was", line[4])
def rain(x, data_set):
for line in data_set:
if(len(x) == 5 and (x[3:5] + "-" + x[0:2]) in line[0]):
print("There was", line[1],"mm rain")
print()
def avgMonth(data_set):
avgList= []
for line in data[1:]:
avgList.append(line[2])
avgList= [float(i) for i in avgList]
avg = sum(avgList)/len(avgList)
print("The average temperature for the 25 day period was", round(avg,1))
def avgLow(data_set):
avgList= []
for line in data[1:]:
avgList.append(line[3])
avgList= [float(i) for i in avgList]
avg = sum(avgList)/len(avgList)
print("The average lowest temperature was", round(avg,1))
def avgHigh(data_set):
avgList= []
for line in data[1:]:
avgList.append(line[4])
avgList= [float(i) for i in avgList]
avg = sum(avgList)/len(avgList)
print("The average highest temperature was", round(avg,1))
print()
def print_tempLine(day, month, temp):
print(day + "." + month + " ", end="")
print(" "*(temp+5) + "-", end="")
print()
def print_tempAxis():
print(" ", end="")
for i in range(-5,16):
print("{:02d} ".format(i), end="")
print()
def scatPlot(data_set):
for line in data[1:]:
day_month=line[0].split("-")
temp=int(round(float(line[2]),0))
print_tempLine(day_month[2],day_month[1],temp)
print_tempAxis()
print()
def menu_number():
number = int(input("Choose what to do: "))
if (number) == 1:
x = input("Give name of the file: " )
loadFile(x)
print_menu()
menu_number()
elif (number) == 2:
x = input("Give a date (dd.mm): ")
avgDay(x, data_set)
lowHigh(x, data_set)
rain(x, data_set)
print_menu()
menu_number()
elif (number) == 3:
avgMonth(data_set)
avgLow(data_set)
avgHigh(data_set)
print_menu()
menu_number()
elif (number) == 4:
scatPlot(data_set)
print_menu()
menu_number()
elif (number) == 0:
sys.exit()
else:
print("\n Your selection is invalid, please try again!\n")
print_menu()
menu_number()
print_menu()
menu_number()
我明白当我 return data_set 在我的 loadFile(x) 中它需要以某种方式分配给一个变量以便它可以在本地范围之外访问时，我只是不知道这是怎么做到的。我尝试在 menu_number 函数中将 loadFile(x) 更改为 data_set = loadFile(x)，这只会导致它给出以下错误 "local variable 'data_set' referenced before assignment"。那么是不是我遗漏了什么或者我需要以某种方式重写代码？
编辑：抱歉没有意识到我需要提供完整的堆栈跟踪错误
Traceback (most recent call last):
File "C:\Users\alexa\Documents\XAMK\python scripts\test.py", line 126, in <module>
menu_number()
File "C:\Users\alexa\Documents\XAMK\python scripts\test.py", line 95, in menu_number
menu_number()
File "C:\Users\alexa\Documents\XAMK\python scripts\test.py", line 99, in menu_number
avgDay(x, data_set)
NameError: name 'data_set' is not defined
编辑 2：csv 示例代码
"DateTime";"Precipitation";"Mean temperature";"Minimum temperature";"Maximum temperature";"Typical maximum temperature";"Typical maximum temperature";"Typical minimum temperature";"Typical minimum temperature";"Fairly typical maximum temperature";"Fairly typical maximum temperature";"Fairly typical minimum temperature";"Fairly typical minimum temperature"
"2019-10-06";0;4;0.4;6.8;10.3;11.9;4.5;7.2;7.6;13.8;0.9;9.8
"2019-10-07";0.1;4.4;2.6;7.8;10.1;11.8;4.4;7;7.4;13.6;0.8;9.7
"2019-10-08";0;4.9;2.3;7.2;10;11.6;4.2;6.9;7.2;13.4;0.6;9.5
"2019-10-09";1.1;4.8;1.8;7.6;9.8;11.4;4.1;6.7;6.9;13.3;0.5;9.4
如果您能提供一个示例 csv 文件，这将很有帮助，以便我可以测试工作流程。但看起来问题在于您调用 loadFile(x)，并且它有一个 return 语句，但没有为该 return 语句设置任何内容。所以你在 data_set = loadFile(x) 的正确轨道上。问题是，当您再次调用 menu_number 函数时，变量值不会被保留。所以在第二次调用时，data_set 失去了意义。
您可以通过将 data_set 的值传递给函数来解决此问题，因此您的 menu_number 看起来更像
def menu_number(data_set=None):
number = int(input("Choose what to do: "))
if (number) == 1:
x = input("Give name of the file: " )
data_set=loadFile(x)
print_menu()
# passing data_set value along
# with the call
menu_number(data_set)
elif (number) == 2:
x = input("Give a date (dd.mm): ")
avgDay(x, data_set)
lowHigh(x, data_set)
rain(x, data_set)
print_menu()
# passing data_set to preserve it
menu_number(data_set)
elif (number) == 3:
avgMonth(data_set)
avgLow(data_set)
avgHigh(data_set)
print_menu()
# passing data_set to preserve it
menu_number(data_set)
elif (number) == 4:
scatPlot(data_set)
print_menu()
# passing data_set to preserve it
menu_number(data_set)
elif (number) == 0:
sys.exit()
else:
print("\n Your selection is invalid, please try again!\n")
print_menu()
# passing data_set to preserve it
menu_number(data_set)
在这个例子中，data_set是一个可选变量。如果你调用 menu_number()，data_set 就是 None。但是在 menu_number(data_set) 的调用中，您可以重用该值。
使 data_set 成为可选参数将防止任何未定义的错误。将其传回给自身将避免您需要一遍又一遍地读取 csv 文件。
1) 您必须执行 data_set = loadFile() 才能收到列表 loadFile() returns.
2) 现在，关于 "local variable 'data_set' referenced before assignment" 错误，它可能发生在 number 不等于 1 时，这会导致您的代码跳过 data_set = loadFile()，并结合事实data_set 在 if 语句的 外部 不被识别，只要你不在更高的范围内声明它（例如函数的开头） ), avgDay(x, data_set) 之类的函数不会将 data_set 识别为变量。
为了解决这个问题，我建议：
1) 在更高的范围内声明data_set。
2) 用户可以选择的每个依赖于 loadFile() 初始化的 data_set 的动作也必须包括这个初始化
所以我之前设置了我的代码来访问一个在函数外部声明的列表，使其成为一个全局变量，对于分配给我的任务，讲师坚持我们不使用全局变量。所以现在我有以下代码，它显然给出了 "data_set undefined error"
我的想法是，我从一个 csv 文件创建一个列表，然后将该列表传递给其他几个函数，这样我就可以从 data_set 列表中获取元素并创建新的输出。
import csv
import sys
def print_menu():
print("ACME WEATHER DATA APP")
print("1) Choose weather data file")
print("2) See data for selected day")
print("3) Calculate average statistics for the data")
print("4) Print a scatterplot of the average temperatures")
print("0) Quit program")
def loadFile(x):
data_set = []
data_set.clear()
with open(x, "r") as readfile:
csv_reader = csv.reader(readfile, delimiter= ';')
for row in csv_reader:
data_set.append(row)
print("Loaded weather data from", (x[0:-4]).capitalize())
print()
return data_set
def avgDay(x, data_set):
for line in data_set:
if(len(x) == 5 and (x[3:5] + "-" + x[0:2]) in line[0]):
print("The weather on", x, "was on average", line[2], "centigrade")
def lowHigh(x, data_set):
for line in data_set:
if(len(x) == 5 and (x[3:5] + "-" + x[0:2]) in line[0]):
print("The lowest temperature was", line[3], "and the highest temperature was", line[4])
def rain(x, data_set):
for line in data_set:
if(len(x) == 5 and (x[3:5] + "-" + x[0:2]) in line[0]):
print("There was", line[1],"mm rain")
print()
def avgMonth(data_set):
avgList= []
for line in data[1:]:
avgList.append(line[2])
avgList= [float(i) for i in avgList]
avg = sum(avgList)/len(avgList)
print("The average temperature for the 25 day period was", round(avg,1))
def avgLow(data_set):
avgList= []
for line in data[1:]:
avgList.append(line[3])
avgList= [float(i) for i in avgList]
avg = sum(avgList)/len(avgList)
print("The average lowest temperature was", round(avg,1))
def avgHigh(data_set):
avgList= []
for line in data[1:]:
avgList.append(line[4])
avgList= [float(i) for i in avgList]
avg = sum(avgList)/len(avgList)
print("The average highest temperature was", round(avg,1))
print()
def print_tempLine(day, month, temp):
print(day + "." + month + " ", end="")
print(" "*(temp+5) + "-", end="")
print()
def print_tempAxis():
print(" ", end="")
for i in range(-5,16):
print("{:02d} ".format(i), end="")
print()
def scatPlot(data_set):
for line in data[1:]:
day_month=line[0].split("-")
temp=int(round(float(line[2]),0))
print_tempLine(day_month[2],day_month[1],temp)
print_tempAxis()
print()
def menu_number():
number = int(input("Choose what to do: "))
if (number) == 1:
x = input("Give name of the file: " )
loadFile(x)
print_menu()
menu_number()
elif (number) == 2:
x = input("Give a date (dd.mm): ")
avgDay(x, data_set)
lowHigh(x, data_set)
rain(x, data_set)
print_menu()
menu_number()
elif (number) == 3:
avgMonth(data_set)
avgLow(data_set)
avgHigh(data_set)
print_menu()
menu_number()
elif (number) == 4:
scatPlot(data_set)
print_menu()
menu_number()
elif (number) == 0:
sys.exit()
else:
print("\n Your selection is invalid, please try again!\n")
print_menu()
menu_number()
print_menu()
menu_number()
我明白当我 return data_set 在我的 loadFile(x) 中它需要以某种方式分配给一个变量以便它可以在本地范围之外访问时，我只是不知道这是怎么做到的。我尝试在 menu_number 函数中将 loadFile(x) 更改为 data_set = loadFile(x)，这只会导致它给出以下错误 "local variable 'data_set' referenced before assignment"。那么是不是我遗漏了什么或者我需要以某种方式重写代码？
编辑：抱歉没有意识到我需要提供完整的堆栈跟踪错误
Traceback (most recent call last):
File "C:\Users\alexa\Documents\XAMK\python scripts\test.py", line 126, in <module>
menu_number()
File "C:\Users\alexa\Documents\XAMK\python scripts\test.py", line 95, in menu_number
menu_number()
File "C:\Users\alexa\Documents\XAMK\python scripts\test.py", line 99, in menu_number
avgDay(x, data_set)
NameError: name 'data_set' is not defined
编辑 2：csv 示例代码
"DateTime";"Precipitation";"Mean temperature";"Minimum temperature";"Maximum temperature";"Typical maximum temperature";"Typical maximum temperature";"Typical minimum temperature";"Typical minimum temperature";"Fairly typical maximum temperature";"Fairly typical maximum temperature";"Fairly typical minimum temperature";"Fairly typical minimum temperature"
"2019-10-06";0;4;0.4;6.8;10.3;11.9;4.5;7.2;7.6;13.8;0.9;9.8
"2019-10-07";0.1;4.4;2.6;7.8;10.1;11.8;4.4;7;7.4;13.6;0.8;9.7
"2019-10-08";0;4.9;2.3;7.2;10;11.6;4.2;6.9;7.2;13.4;0.6;9.5
"2019-10-09";1.1;4.8;1.8;7.6;9.8;11.4;4.1;6.7;6.9;13.3;0.5;9.4
如果您能提供一个示例 csv 文件，这将很有帮助，以便我可以测试工作流程。但看起来问题在于您调用 loadFile(x)，并且它有一个 return 语句，但没有为该 return 语句设置任何内容。所以你在 data_set = loadFile(x) 的正确轨道上。问题是，当您再次调用 menu_number 函数时，变量值不会被保留。所以在第二次调用时，data_set 失去了意义。
您可以通过将 data_set 的值传递给函数来解决此问题，因此您的 menu_number 看起来更像
def menu_number(data_set=None):
number = int(input("Choose what to do: "))
if (number) == 1:
x = input("Give name of the file: " )
data_set=loadFile(x)
print_menu()
# passing data_set value along
# with the call
menu_number(data_set)
elif (number) == 2:
x = input("Give a date (dd.mm): ")
avgDay(x, data_set)
lowHigh(x, data_set)
rain(x, data_set)
print_menu()
# passing data_set to preserve it
menu_number(data_set)
elif (number) == 3:
avgMonth(data_set)
avgLow(data_set)
avgHigh(data_set)
print_menu()
# passing data_set to preserve it
menu_number(data_set)
elif (number) == 4:
scatPlot(data_set)
print_menu()
# passing data_set to preserve it
menu_number(data_set)
elif (number) == 0:
sys.exit()
else:
print("\n Your selection is invalid, please try again!\n")
print_menu()
# passing data_set to preserve it
menu_number(data_set)
在这个例子中，data_set是一个可选变量。如果你调用 menu_number()，data_set 就是 None。但是在 menu_number(data_set) 的调用中，您可以重用该值。
使 data_set 成为可选参数将防止任何未定义的错误。将其传回给自身将避免您需要一遍又一遍地读取 csv 文件。
1) 您必须执行 data_set = loadFile() 才能收到列表 loadFile() returns.
2) 现在，关于 "local variable 'data_set' referenced before assignment" 错误，它可能发生在 number 不等于 1 时，这会导致您的代码跳过 data_set = loadFile()，并结合事实data_set 在 if 语句的 外部 不被识别，只要你不在更高的范围内声明它（例如函数的开头） ), avgDay(x, data_set) 之类的函数不会将 data_set 识别为变量。
为了解决这个问题，我建议：
1) 在更高的范围内声明data_set。
2) 用户可以选择的每个依赖于 loadFile() 初始化的 data_set 的动作也必须包括这个初始化