python - 尝试将字典写入 CSV 文件时，Str 属性没有键

Question

我正在尝试使用以下代码将字典写入 CSV 文件:

def condense_data(in_file, out_file, city):
"""
This function takes full data from the specified input file
and writes the condensed data to a specified output file. The city
argument determines how the input file will be parsed.

HINT: See the cell below to see how the arguments are structured!
"""

with open(out_file, 'w') as f_out, open(in_file, 'r') as f_in:
    # set up csv DictWriter object - writer requires column names for the
    # first row as the "fieldnames" argument

    out_colnames = ['duration', 'month', 'hour', 'day_of_week', 'user_type']        
    trip_writer = csv.DictWriter(f_out, fieldnames = out_colnames)
    trip_writer.writeheader()

    ## TODO: set up csv DictReader object ##
    trip_reader = csv.DictReader(f_in)

    # collect data from and process each row
    for row in trip_reader:
        # set up a dictionary to hold the values for the cleaned and trimmed
        # data point
        new_point = {}

        ## TODO: use the helper functions to get the cleaned data from  ##
        ## the original data dictionaries.                              ##
        ## Note that the keys for the new_point dictionary should match ##
        ## the column names set in the DictWriter object above.         ##

        duration = duration_in_mins(row, city)
        month, hour, day_of_week = time_of_trip(row, city)
        user_type = type_of_user(row, city)
        new_point = {'duration': duration, 'month': month, 'hour': hour,
                     'day_of_week': day_of_week, 'user_type': user_type}



        print(new_point) # Works fine till here, I am able print the right output
        trip_writer.writerows(new_point) # throws an error

下面是抛出的错误:

AttributeError Traceback (most recent call last) in () 8 9 for city, filenames in city_info.items(): ---> 10 condense_data(filenames['in_file'], filenames['out_file'], city) 11 print_first_point(filenames['out_file'])

in condense_data(in_file, out_file, city) 38 ## see https://docs.python.org/3/library/csv.html#writer-objects ## 39 print(new_point) ---> 40 trip_writer.writerows(new_point) 41 42

/opt/conda/lib/python3.6/csv.py in writerows(self, rowdicts) 156 157 def writerows(self, rowdicts): --> 158 return self.writer.writerows(map(self._dict_to_list, rowdicts)) 159 160 # Guard Sniffer's type checking against builds that exclude complex()

/opt/conda/lib/python3.6/csv.py in _dict_to_list(self, rowdict) 146 def _dict_to_list(self, rowdict): 147 if self.extrasaction == "raise": --> 148 wrong_fields = rowdict.keys() - self.fieldnames 149 if wrong_fields: 150 raise ValueError("dict contains fields not in fieldnames: "

AttributeError: 'str' object has no attribute 'keys'

我确实在 Stack Overflow 上看过这类问题，但没有一个有帮助。

Answer 1

您在应该使用 writerow() 的地方使用了 writerows()，因为您正在尝试写入一行，而不是它们的列表。