Using Numpy to create Yahoo finance price table

Without using matplotlib finance 开发者_StackOverflow中文版module. I like to get the url data into a numpy array. where I can to column heading to do math. Like:

prices = r.adj_close

From: http://matplotlib.sourceforge.net/examples/pylab_examples/finance_work2.html

except I dont want to use the:

fh = finance.fetch_historical_yahoo(ticker, startdate, enddate)
# a numpy record array with fields: date, open, high, low, close, volume, adj_close)

r = mlab.csv2rec(fh); fh.close()
r.sort()

Using manually create the url:

        url = http://ichart.yahoo.com/table.csv?a=2&c=2011&b=30&e=7&d=7&g=d&f=2011&s=msft&ignore=.csv

        f = urllib.urlopen(url)
        fr = f.read()



        hdata = np.asarray(fr, dtype='object')
        prices = hdata.adj_close
        print prices

use numpy.loadtxt() to load csv:

import numpy as np
import pylab as pl
import urllib
url = "http://ichart.yahoo.com/table.csv?a=2&c=2011&b=30&e=7&d=7&g=d&f=2011&s=msft&ignore=.csv"
f = urllib.urlopen(url)
title = f.readline().strip().split(",")
data = np.loadtxt(f, dtype=np.float, delimiter=",", converters={0: pl.datestr2num}))

the first column is date, so use pylab.datestr2num to convert it to number.

If you don't want to load pylab for time string conversion, you can use the mktime function as a lambda:

import numpy as np
import urllib
import time 
url = "http://ichart.yahoo.com/table.csv?a=2&c=2011&b=30&e=7&d=7&g=d&f=2011&s=msft&ignore=.csv" 
f = urllib.urlopen(url) 
title = f.readline().strip().split(",") 
data = np.loadtxt(f, dtype={'names': ('dtime', 'open', 'high','low','close','volume','aclose'),
                            'formats': ('u4', 'f8', 'f8','f8','f8','u4','f8')}, 
                     delimiter=",", 
                     converters={0: lambda y:int(time.mktime(time.strptime(y,'%Y-%m-%d')))})

It is also possible to use S10 to tell numpy that the first entity is a string with length 10. This way, you don't need to use lambda.

data = np.loadtxt(f, dtype={'names': ('dtime', 'open', 'high','low','close','volume','aclose'), 'formats': ('S10', '<f8', '<f8','<f8','<f8','i','<f8')}, 
                             delimiter="," )

i=integer, <f8 =0.256, f8=0.25600001298, S10="MM-DD-YYYY"

For more info on f, f8, u4, S, u8 etc, visit this link.