如何解决尝试访问词典列表的最后一个值时遇到关键错误
背景:编写程序以从Web提取选项链数据。 为了显示代码的编写方式,请看下面。 (不是实际的代码,而只是一种表示形式) 该代码主要包含注释,以描述每个代码块中正在发生的事情。 问题是,当我第一次运行代码时,如果不执行条件操作,则会在其中一行代码。我在代码本身中添加了注释,以使这一点更清楚。当我运行代码时,出现错误:
回溯(最近通话最近): 文件“ D:\ AC \ Coursera Course \ Python for Everyone \ Course 1- Python入门Python \ Python程序\ nse_data.py”,第222行,在 主要() 主文件“ D:\ AC \ Coursera Course \ Python for Everyone \ Course 1- Python入门Python \ Python程序\ nse_data.py”,第218行 data_log(r) 文件“ D:\ AC \ Coursera Course \ Python for Everyone \ Course 1- Python入门Python \ Python程序\ nse_data.py”,行187,在data_log中 all_data ['Time'] = df_list [-1] [0] ['Time'] KeyError:-1
import requests
import json
url = 'some url'
data_list = [] # needs to be a list of dictionaries that contain data
# creating 1 file to store all the data for each day,this will be present in 'data_log' folder in current directory after the 1st time program runs for the day
log_file = os.path.join('data_log','oi_records_{0}.json'.format(datetime.datetime.now().strftime('%d%m%y')))
def get_OI_data:
# No problem in this function
r = requests(url).json()
# fetched data has this format:
https://drive.google.com/file/d/1Z0Va8obzvW29ZlYdrAljFgdUlUlqT4qy/view?usp=sharing
#return dict data
return r
def write_OI_data:
# No problem in this function
# function to write data into an excel file
print('data written to excel')
def data_log(r):
# the second time we reach here,data_list will contain value of the key records from 'all_data'
all_ce = [items['CE']for items in r['records']['data'] if 'CE' in items]
all_pe = [items['PE']for items in r['records']['data'] if 'PE' in items]
# converting into a dataframe
all_df_ce = pd.DataFrame(all_ce)
all_df_pe = pd.DataFrame(all_pe)
# adding a new column type
all_df_ce['Type'] = 'CE'
all_df_pe['Type'] = 'PE'
all_data = pd.concat([all_df_ce,all_df_pe])
# adding 2 if conditions to check if the data is duplicate or not
# problem in line below,Why is the program entering inside condition below the 1st time time program runs??
# since data_list is initiated as empty list,its length should be 0 hence both conditions below should be skipped the 1st time data in fetched in a day
if len(data_list) > 0:
# trying to set time column in all_data equal to the time value in last value of data_list
all_data['Time'] = data_list[-1][0]['Time']
# Problem in above line...program entering the the conditional block even though data_list is initiated as null
if len(data_list) > 0 and all_data.to_dict('records') == data_list[-1]:
print('Duplicate data present,no need to record: ')
sleep(10)
# need to add more code here to reroute the flow of the dode.
all_data['Time'] = datetime.datetime.now().strftime('%H:%M')
data_list.append(all_data.to_dict('records'))
with open(log_file,'w') as file:
file.write(json.dumps(data_list,indent = 4,sort_keys = True))
def main():
r = get_OI_data()
write_OI_data(r)
global data_list
try:
# Reading log file if it exists other wise setting data_list as an empty list
data_list = json.loads(open(log_file).read())
except:
print('Error reading Previous log file: ')
data_list = []
data_log(r)
if __name__ == '__main__':
main()
版权声明:本文内容由互联网用户自发贡献,该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务,不拥有所有权,不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容, 请发送邮件至 dio@foxmail.com 举报,一经查实,本站将立刻删除。