我有一个数据文件，其中包含某些特定格式的数据，并且在处理时有一些额外的行要忽略。我需要处理数据并基于该数据计算一个值。
样本数据：
Average monthly temperatures in Dubuque, Iowa,
January 1964 through december 1975, n=144
24.7 25.7 30.6 47.5 62.9 68.5 73.7 67.9 61.1 48.5 39.6 20.0
16.1 19.1 24.2 45.4 61.3 66.5 72.1 68.4 60.2 50.9 37.4 31.1
10.4 21.6 37.4 44.7 53.2 68.0 73.7 68.2 60.7 50.2 37.2 24.6
21.5 14.7 35.0 48.3 54.0 68.2 69.6 65.7 60.8 49.1 33.2 26.0
19.1 20.6 40.2 50.0 55.3 67.7 70.7 70.3 60.6 50.7 35.8 20.7
14.0 24.1 29.4 46.6 58.6 62.2 72.1 71.7 61.9 47.6 34.2 20.4
8.4 19.0 31.4 48.7 61.6 68.1 72.2 70.6 62.5 52.7 36.7 23.8
11.2 20.0 29.6 47.7 55.8 73.2 68.0 67.1 64.9 57.1 37.6 27.7
13.4 17.2 30.8 43.7 62.3 66.4 70.2 71.6 62.1 46.0 32.7 17.3
22.5 25.7 42.3 45.2 55.5 68.9 72.3 72.3 62.5 55.6 38.0 20.4
17.6 20.5 34.2 49.2 54.8 63.8 74.0 67.1 57.7 50.8 36.8 25.5
20.4 19.6 24.6 41.3 61.8 68.5 72.0 71.1 57.3 52.5 40.6 26.2
样本文件的来源：http://robjhyndman.com/tsdldata/data/cryer2.dat
注意：此处，行代表年份，列代表月份。
我正在尝试编写一个函数，该函数从给定的URL返回任何月份的平均温度。
我尝试如下：
def avg_temp_march(f):
march_temps = []
# read each line of the file and store the values
# as floats in a list
for line in f:
line = str(line, 'ascii') # now line is a string
temps = line.split()
# check that it is not empty.
if temps != []:
march_temps.append(float(temps[2]))
# calculate the average and return it
return sum(march_temps) / len(march_temps)
avg_temp_march("data5.txt")
但我收到错误
line = str(line, 'ascii')TypeError: decoding str is not supported
最佳答案
我认为没有必要将字符串转换为字符串。
我尝试通过一些修改来修复您的代码：
def avg_temp_march(f):
# f is a string read from file
march_temps = []
for line in f.split("\n"):
if line == "": continue
temps = line.split(" ")
temps = [t for t in temps if t != ""]
# check that it is not empty.
month_index = 2
if len(temps) > month_index:
try:
march_temps.append(float(temps[month_index]))
except Exception, e:
print temps
print "Skipping line:", e
# calculate the average and return it
return sum(march_temps) / len(march_temps)
输出：
['Average', 'monthly', 'temperatures', 'in', 'Dubuque,', 'Iowa,']
Skipping line: could not convert string to float: temperatures
['January', '1964', 'through', 'december', '1975,', 'n=144']
Skipping line: could not convert string to float: through
32.475
根据您的原始问题（在进行最新编辑之前），我认为您可以通过这种方式解决您的问题。
# from urllib2 import urlopen
from urllib.request import urlopen #python3
def avg_temp_march(url):
f = urlopen(url).read()
data = f.split("\n")[3:] #ingore the first 3 lines
data = [line.split() for line in data if line!=''] #ignore the empty lines
data = [map(float, line) for line in data] #Convert all numbers to float
month_index = 2 # 2 for march
monthly_sum = sum([line[month_index] for line in data])
monthly_avg = monthly_sum/len(data)
return monthly_avg
print avg_temp_march("http://robjhyndman.com/tsdldata/data/cryer2.dat")