【优达学城测评】Parsing CSV Files（python）

最新推荐文章于 2019-05-23 10:09:41 发布

转载最新推荐文章于 2019-05-23 10:09:41 发布 · 143 阅读

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原文链接：https://my.oschina.net/Bettyty/blog/755487

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本文介绍了一个Python函数parse_file，用于从CSV文件中读取并解析前10行数据，每行数据转换为一个字典，键为字段名，值为对应的数据。此函数返回一个包含这些字典的列表。

2019独角兽企业重金招聘Python工程师标准>>>

# Your task is to read the input DATAFILE line by line, and for the first 10 lines (not including the header)
# split each line on "," and then for each line, create a dictionary
# where the key is the header title of the field, and the value is the value of that field in the row.
# The function parse_file should return a list of dictionaries,
# each data line in the file being a single list entry.
# Field names and values should not contain extra whitespace, like spaces or newline characters.
# You can use the Python string method strip() to remove the extra whitespace.
# You have to parse only the first 10 data lines in this exercise,
# so the returned list should have 10 entries!
import os

DATADIR = ""
DATAFILE = "beatles-diskography.csv"

def parse_file(datafile):
data = []
with open(datafile, "r") as f:
header=f.readline().split(",")
counter=0
for line in f:
if counter==10:
break
fields=line.split(",")
entry={}

for i,value in enumerate(fields):
entry[header[i].strip()]=value.strip()
data.append(entry)
counter+=1

return data

def test():
# a simple test of your implemetation
datafile = os.path.join(DATADIR, DATAFILE)
d = parse_file(datafile)
firstline = {'Title': 'Please Please Me', 'UK Chart Position': '1', 'Label': 'Parlophone(UK)', 'Released': '22 March 1963', 'US Chart Position': '-', 'RIAA Certification': 'Platinum', 'BPI Certification': 'Gold'}
tenthline = {'Title': '', 'UK Chart Position': '1', 'Label': 'Parlophone(UK)', 'Released': '10 July 1964', 'US Chart Position': '-', 'RIAA Certification': '', 'BPI Certification': 'Gold'}

assert d[0] == firstline
assert d[9] == tenthline

test()

Python string method strip() will come in handy to get rid of the extra whitespace (that includes newline character at the end of line)

转载于:https://my.oschina.net/Bettyty/blog/755487