python读取⼤⽂件csv_python–从csv⽂件的每⼀列获取最⼤值有⼈帮我解决以下问题.我⾃⼰尝试过，我也附上了解决⽅案.我使⽤了2-d列表，但我想要⼀个没有2-d列表的不同解决⽅案，它应该更加pythonic.
pl建议我你们中的任何⼀个⼈都有其他办法.
Q)考虑CSV⽂件中⾃1990年以来每⽉给出的N个公司的股价.⽂件格式如下，第⼀⾏为标题.
年,⽉，公司A，公司B，公司C,………….公司N.
1990年1⽉10⽇,15⽇,20⽇,……….,50
摩托车脱审1990年2⽉10⽇,15⽇,20⽇,……….,50
.
.
.
.
2013年9⽉,50⽇,10⽇,15⽇ (500)
解决⽅案应该采⽤这种格式.
a)股价最⾼的每个公司年⽉的清单.
这是我使⽤2-d列表的答案.
云南警官学院分数线def generate_list(file_path):
'''
return list of list's containing file data.'''
data_list=None #local variable
try:
file_obj = open(file_path,'r')有志者事竟成的事例
try:
gen = (line.split(',') for line in file_obj) #generator, to generate one line each time until EOF (End of File)
for j,line in enumerate(gen):
if not data_list:
#if dl is None then create list containing n empty lists, where n will be number of columns.
data_list = [[] for i in range(len(line))]
if line[-1].find('\n'):
line[-1] = line[-1][:-1] #to remove last list element's '\n' character
#loop to convert numbers from string to float, and leave others as strings only
for i,l in enumerate(line):
if i >=2 and j >= 1:
data_list[i].append(float(l))
el:
data_list[i].append(l)
except IOError, io_except:
print io_except
finally:
file_obj.clo()
except IOError, io_exception:
print io_exception
return data_list
def generate_result(file_path):
'''
return list of tuples containing (max price, year, month,
company name).
'''
data_list = generate_list(file_path)
re=[] #list to store results in tuple formet as follow [(max_price, year, month, company_name), ....] if data_list:
for i,d in enumerate(data_list):
if i >= 2:
m = max(data_list[i][1:]) #max_price for the company
idx = data_list[i].index(m) #getting index of max_price in the list
yr = data_list[0][idx] #getting year by using index of max_price in list
mon = data_list[1][idx] #getting month by using index of max_price in list
com = data_list[i][0] #getting company_name
re.append((m,yr,mon,com))
return re
if __name__ == '__main__':
file_path = 'C:/Document and Settings/RajeshT/Desktop/nothing/imp/New Folder/tst.csv'
re = generate_result(file_path)
print 'result ', re
我试图⽤发电机解决它，但在那种情况下，它只给出了⼀个公司的结果，即只有⼀列.
p = 'filepath.csv'
f = open(p,'r')
head = f.readline()
gen = ((float(line.split(',')[n]), line.split(',',2)[0:2], head.split(',')[n]) for n in range(2,len(head.split(','))) for i,line in enumerate(f)) x = max((i for i in gen),key=lambda x:x[0])
print x
您可以采⽤以下提供的csv格式的输⼊数据.
year,month,company 1,company 2,company 3,company 4,company 5
我们的冬奥1990,jan,201,245,243,179,133
1990,feb,228,123,124,121,180
1990,march,63,13,158,88,79
1990,april,234,68,187,67,135
1990,may,109,128,46,185,236
1990,june,53,36,202,73,210
疾在腠理
1990,july,194,38,48,207,72
1990,august,147,116,149,93,114
1990,ptember,51,215,15,38,46
1990,october,16,200,115,205,118
1990,november,241,86,58,183,100
1990,december,175,97,143,77,84
1991,jan,190,68,236,202,19
1991,feb,39,209,133,221,161
1991,march,246,81,38,100,122
1991,april,37,137,106,138,26
笑声1991,may,147,48,182,235,47
1991,june,57,20,156,38,245
1991,july,165,153,145,70,157
1991,august,154,16,162,32,21
1991,ptember,64,160,55,220,138
1991,october,162,72,162,222,179
1991,november,215,207,37,176,30
1991,december,106,153,31,247,69
预期产量如下.
[(246.0, '1991', 'march', 'company 1'),
(245.0, '1990', 'jan', 'company 2'),
(243.0, '1990', 'jan', 'company 3'),
(247.0, '1991', 'december', 'company 4'),
(245.0, '1991', 'june', 'company 5')]
菱形的判定方法
提前致谢…
解决⽅法:
使⽤collections.OrderedDict和collections.namedtuple：
import csv
from collections import OrderedDict, namedtuple
with open('abc1') as f:
reader = ader(f)
tup = namedtuple('tup', ['price', 'year', 'month'])
d = OrderedDict()
names = next(reader)[2:]
for name in names:
#initialize the dict
d[name] = tup(0, 'year', 'month')
for row in reader:
year, month = row[:2] # U year, month, *prices = row in py3.x
for name, price in zip(names, map(int, row[2:])): # map(int, prices) py3.x if d[name].price < price:
d[name] = tup(price, year, month)
print d
如何画水果输出：
OrderedDict([
('company 1', tup(price=246, year='1991', month='march')),
('company 2', tup(price=245, year='1990', month='jan')),
('company 3', tup(price=243, year='1990', month='jan')),
('company 4', tup(price=247, year='1991', month='december')),
('company 5', tup(price=245, year='1991', month='june'))])
标签：python,python-3-x,python-2-7,csv,generator
