python - python文件中年和月数据的平均温度

Question

我有一个数据文件，其中包含某种特定格式的数据，并且在处理时需要忽略一些额外的行。我需要处理数据并根据数据计算值。

示例数据:

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

示例文件来源: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，它从给定的网址返回任何月份的平均温度。

我尝试过如下:

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

Answer 1

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

根据您原来的问题(在最新编辑之前)，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")