今天我在Python中遇到了一件非常奇怪的事情:字符串和字典。谁能给我解释一下为什么print语句在第一个for循环中工作,而在第二个for循环中失败?
test = 'ab'
test_dict = {}
test_dict[test] = 1
for x, y in test_dict:
print('%s %s' % (x,y))
for x,y in test:
print('%s %s' % (x,y))
我正在尝试打开一个播放列表(从iTunes导出为XML文件)在Python中作为字典。我试过这个:
import plistlib
plist = plistlib.readPlist(fileName)
print(plist)
它给我打印了一个字典,但有这样一条消息:
DeprecationWarning: The readPlist function is deprecated, use load() instead
在Peter Norvig的用Python ()编写的Lisp解释器中,他将Lisp的eval定义为:
def eval(x, env=global_env):
"Evaluate an expression in an environment."
if isa(x, Symbol): # variable reference
return env.find(x)[x]
elif not isa(x, list): # constant literal
return x
所以这是我的代码: def main():
import combinedparser as cp
from tkinter.filedialog import askopenfilenames
files = askopenfilenames()
print(files) #this gives the right files as a list of strings composed of path+filename
def file_discriminator(func):
def wrapper():
我已经阅读了关于这个python错误的所有其他问题,但没有一个对我有帮助,我是python的初学者,真的需要帮助。我必须从一个文件中找出一些学生结果的平均值,然后在第4行和第7行计算出要解包的多个错误值
fileName = classChoice + ".txt" # generate the name of the file to read
with open (fileName) as f:
for line in f.readlines():
userName,score= line.split(' : ')
sc
因此,我制作了自己的基于dict的命名元组类:
class t(dict):
def __getattr__(self, v):
try:
return self[v]
except KeyError:
raise AttributeError("Key " + str(v) + " does not exist.")
def __init__(self, *args, **kwargs):
for source in args:
for i, j in sou
python和编程的新手。如何使用for循环创建包含两个API的字典(一个从标准普尔500公司的字典中提取股票代码,另一个是yahoo_finance,用于提取相应的市值数据),并且还可以更新以替换现有数据。
import sp500
from yahoo_finance import Share
tickers = {}
for d in sp500:
for k, v in tickers.items():
retrieveticker = d['symbol']
yahoodata = Share(retrieveticker)