如何将几个函数应用于列表中的多个股票代码?(代码改进)

Question

所以我目前正在学习如何使用numpy，pandas等在python中分析财务数据......我从一个小脚本开始，希望通过2个选定日期之间的价格变化对一些选定的股票进行排名。 我的第一个脚本是：

import numpy as np
import pandas as pd
from pandas_datareader import data as web
from pandas import Series, DataFrame
import datetime
from operator import itemgetter
#Edit below for 2 dates you wish to calculate:
start = datetime.datetime(2014, 7, 15)
end = datetime.datetime(2017, 7, 25)
stocks = ('AAPL', 'GOOGL', 'YHOO', 'MSFT', 'AMZN', 'DAI')
#Getting the data:    
AAPL = web.DataReader('AAPL', 'google', start, end)
GOOGL = web.DataReader('GOOGL', 'google', start, end)
YHOO = web.DataReader('YHOO', 'google', start, end)
MSFT = web.DataReader('MSFT', 'google', start, end)
AMZN = web.DataReader('AMZN', 'google', start, end)
DAI = web.DataReader('DAI', 'google', start, end)
#Calculating the change:
AAPLkey = (AAPL.ix[start]['Close'])/(AAPL.ix[end]['Close'])
GOOGLkey = (GOOGL.ix[start]['Close'])/(GOOGL.ix[end]['Close'])
YHOOkey = (YHOO.ix[start]['Close'])/(YHOO.ix[end]['Close'])
MSFTkey = (MSFT.ix[start]['Close'])/(MSFT.ix[end]['Close'])
AMZNkey = (AMZN.ix[start]['Close'])/(AMZN.ix[end]['Close'])
DAIkey = (DAI.ix[start]['Close'])/(DAI.ix[end]['Close'])
#Formatting the output in a sorted order:
dict1 = {"AAPL" : AAPLkey, "GOOGL" : GOOGLkey, "YHOO" : YHOOkey, "MSFT" : MSFTkey, "AMZN" : AMZNkey, "DAI" : DAIkey}
out = sorted(dict1.items(), key=itemgetter(1), reverse = True)
for tick , change in out:
print (tick,"t", change)

我现在显然想让它更短，这就是我到目前为止得到的：

import numpy as np
import pandas as pd
from pandas_datareader import data as web
from pandas import Series, DataFrame
import datetime
from operator import itemgetter
#Edit below for 2 dates you wish to calculate:
start = datetime.datetime(2014, 7, 15)
end = datetime.datetime(2017, 7, 25)
stocks = ('AAPL', 'GOOGL', 'YHOO', 'MSFT', 'AMZN', 'DAI')
for eq in stocks:
eq = web.DataReader(eq, 'google', start, end)
for legend in eq:
legend = (eq.ix[start]['Close'])/(eq.ix[end]['Close'])
print (legend)

计算有效，但问题是这只输出列表中项目的最后一个值 (DAI(。 那么，为了获得与我的第一个代码相同的结果，下一步是什么？

Answer 1

您可以将 print 语句移动到循环中。

喜欢：

for legend in eq:
legend = (eq.loc[start]['Close'])/(eq.loc[end]['Close'])
print(legend)

改进的答案： 摆脱标签循环并从前一个循环中打印值：

for eq in stocks:
df = web.DataReader(eq, 'google', start, end)
print((df.loc[start]['Close'])/(df.loc[end]['Close']))

Answer 2

当您在第for eq in stocks行循环查看股票时，您将结果保存到eq中。因此，在每次迭代中，它都会被覆盖。您应该将结果存储在列表中，就像我使用data所做的那样。

然后循环访问包含数据帧的data列表，然后使用正确的选择。

import numpy as np
import pandas as pd
from pandas_datareader import data as web
from pandas import Series, DataFrame
import datetime
from operator import itemgetter
# edit below for 2 dates you wish to calculate:
start = datetime.datetime(2014, 7, 15)
end = datetime.datetime(2017, 7, 25)
stocks = ('AAPL', 'GOOGL', 'YHOO', 'MSFT', 'AMZN', 'DAI')
# store all the dataframes in a list
data = []
for eq in stocks:
data.append(web.DataReader(eq, 'google', start, end))
# print required fields from each dataframe
for df in data:
print (df.ix[start]['Close'])/(df.ix[end]['Close'])

输出：

0.624067042032
0.612014075932
0.613225417599
0.572179539021
0.340850298595
1.28323537643

Answer 3

多亏了其他答案，他们都帮了大忙。由于这种帮助，这是我最终改进的脚本：

import numpy as np
import pandas as pd
from pandas_datareader import data as web
from pandas import Series, DataFrame
import datetime
from operator import itemgetter
# edit below for 2 dates you wish to calculate:
start = datetime.datetime(2014, 7, 15)
end = datetime.datetime(2017, 7, 25)
stocks = ('AAPL', 'GOOGL', 'YHOO', 'MSFT', 'AMZN', 'DAI')
dict1 = {}
for eq in stocks:
df = web.DataReader(eq, 'google', start, end)
k = ((df.loc[start]['Close'])/(df.loc[end]['Close']))
dict1 [eq] = k
out = sorted(dict1.items(), key=itemgetter(1), reverse = True)
for tick , change in out:
print (tick,"t", change)