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Python 强化训练:第九篇

主题

数据处理

  1. csv文件
  2. json文件
  3. xml: xpath
  4. excel

1.

  1. CSV: 逗号分隔值,其文件以纯文本形式存储表格数据(数字和文本)。
  2. 模块:csv
  3. 方法:csv.reader(), csv.writer(), csv.Dictreader(), csv.writerow(), csv.writerows()
import csv
headers = ['Symbol', 'Price', 'Date', 'Time', 'Change', 'Volume']
rows = [('AA', 39.48, '6/11/2007', '9:36am', -0.18, 181800),
         ('AIG', 71.38, '6/11/2007', '9:36am', -0.15, 195500),
         ('AXP', 62.58, '6/11/2007', '9:36am', -0.46, 935000),
       ]

with open('name.csv', newline="") as f:
    f_csv = csv.reader(f)
    headers = next(f_csv)
    print(headers)
    print("=====")
    for row in f_csv:
        print(row)
        print("===")

写入文件形式:

1478869402821.png

要求:将name.csv文件中Volume的值大于195500的数据写入name_copy.csv文件中.

import codecs
import csv

with codecs.open("name_copy.csv", 'w') as f_name_copy:
    f_name_one = csv.writer(f_name_copy)
    with codecs.open("name.csv", 'r') as f_name:
        f_name_two = csv.reader(f_name)
        headers = next(f_name_two)
        f_name_one.writerow(headers)
        for one in f_name_two:
            print(one)
            if int(one[5]) > 195500:
                f_name_one.writerow(one)

文件显示:

1478869756196.png

要求:获取雅虎指定股票历史数据,并存入csv文件中.

import requests
import csv
import codecs

response = requests.get('http://table.finance.yahoo.com/table.csv?s=000001.sz')
content = response.text

with codecs.open("pingan.csv", 'w') as f:
    content_all = csv.writer(f)
    for one in content.split('\n'):
        content_all.writerow(one.split(','))

Paste_Image.png

2.

python 如何处理json文件:

  1. json 模块
  2. dumps(),dump(), loads(),load()方法
import json
import codecs
# json.dumps()
# json.loads()
# json.dump()  # 接口是一个文件
# json.load()  # 接口是一个文件

one = {"wuhan": 10, "beijing": 1, "changsha": 6}
two = [1, 2, "apple", 'chuizi', {"a": 1, "b": 2}]
one_json = json.dumps(one, separators=[",  ", ":  "], indent=4)
one_1_json = json.dumps(one, sort_keys=True)
two_json = json.dumps(two, separators=[",", ":"])
print(one_json)
print(one_1_json)
print(two_json)

with codecs.open("one.json", 'w') as f:
     json.dump(one, f)

with codecs.open("one.json", 'r') as f:
    print(json.load(f))

转换对照表:

python

json

dict

object

list,tuple

array

str,unicode

string

int,long,float

number

True

true

False

false

None

null

print(json.dumps(None))
print(json.dumps(True))
print(json.dumps(False))

print(json.loads("null"))
print(json.loads("true"))
print(json.loads("false"))

# with codecs.open("one.json", 'w') as f:
#     json.dump(one, f)

with codecs.open("one.json", 'r') as f:
    print(json.load(f))


res = requests.get("http://www.weather.com.cn/data/cityinfo/101010100.html")
with codecs.open("weather.json", 'w', encoding="utf8") as f_wea:
    json.dump(res.text, f_wea)

with codecs.open("weather.json", 'r') as f_wea_r:
    A = json.load(f_wea_r)

print(A)

3.

xpath语法:

Syntax

Meaning

tag

Selects all child elements with the given tag.

*

Selects all child elements.

.

Selects the current node.

//

Selects all subelements, on all levels beneath the current element.

..

Selects the parent element.

[@atrrib]

Selects all elements that have the given attribute.

[@atrrib='value']

Selects all elements for which the given attribute has the given value.

[tag]

Selects all elements that have a child named tag.

[tag="text"]

Selects all elements that have a child named tag whose complete text content, including descendants, equals the given text.

[position]

Selects all elements that are located at the given position.

from xml.etree.ElementTree import parse
import requests
import codecs
tree = parse("html.xml")
root = tree.getroot()
print(root.tag)
print(root.attrib)
for child in root:
    print(child.tag, child.attrib)

# tag: 查找给定标签的子节点
print(root.findall('country'))

# *:查找所有子节点
print(root.findall("*"))

# . : 查找当前节点
print(root.findall("."))

# // :所有子孙节点
print(root.findall('.//'))

# .. : 父节点
print(root.findall('.//rank/..'))

# [@atrrib] :带有这个属性值的元素
print(root.findall('.//country[@name]'))

# [@atrrib=“value”]
print(root.findall('.//country[@name="Liechtenstein"]'))

# [tag] : 带有tag子节点的节点
print(root.findall('[country]'))

4.

  1. 模块: xlrd, xlwt
  2. 功能: 负责读写操作

book.xlsx文件内容和结构:

1478938867731.png

import xlrd
import xlwt
name = xlrd.open_workbook('book.xlsx')
sheet = name.sheets()
for one in sheet:
    print(one.name)
result = name.sheet_by_name('result')
print(result.nrows, result.ncols)
one_one = result.cell(0, 0)
one_two = result.cell(0, 1)
one_three = result.cell(0, 2)
one_four = result.cell(0, 3)

# 1: text  2: number
print(one_one.ctype, one_one.value)
print(one_two.ctype, one_two.value)
print(one_three.ctype, one_three.value)
print(one_four.ctype, one_four.value)

print(result.row(1))
print(result.row_values(1))
print(result.row_values(1, 1))
print(result.col(1))
print(result.col_values(1))
print(result.col_values(1, 1))

result.put_cell(0, result.ncols, xlrd.XL_CELL_TEXT, u"总分", None)
for row in range(1, result.nrows):
    t = sum(result.row_values(row, 1))
    print(t)
    result.put_cell(row, result.ncols, xlrd.XL_CELL_NUMBER, t, None)

wbook = xlwt.Workbook()
wsheet = wbook.add_sheet("Sheet1")

style = xlwt.easyxf("align: vertical center, horizontal center")
value = [["名称", "hadoop编程实战", "hbase编程实战", "lucene编程实战"], ["价格", "52.3", "45", "36"], ["出版社", "机械工业出版社", "人民邮电出版社", "华夏人民出版社"], ["中文版式", "中", "英", "英"]]
for i in range(0, 4):
    for j in range(0, len(value[i])):
        wsheet.write(i, j, value[i][j], style)
wbook.save("wbook1.xls")

friend = name.sheet_by_index(1)
friend_copy = name.sheet_by_name("friend")

print(friend.nrows, friend.ncols)
print(friend_copy.nrows, friend_copy.ncols)

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