python读写csv文件方法详细总结

sudo pip install pandas

sudo pip3 install pandas

#encoding:utf-8
import csv
 
#读取csv文件
csv_file = csv.reader(open('../../data/capital/2010-Q4-cabi-trip-history-data.csv'))
print(csv_file)
 
#添加newline可以避免一行之后的空格,这样需要在python3环境下运行
out = open('../../data/capital/2010-Q4','a',newline='')
csv_write = csv.writer(out,dialect='excel')
 
for item in csv_file:
	#print item
	csv_write.writerow(item)
 
print("write over")

#encoding:utf-8
import csv
 
#下面这种加了encoding的写法需要在python3环境下运行
csv_reader = csv.reader(open('../../data/capital/2011-Q1-cabi-trip-history-data.csv',encoding='utf-8'))
 
out = open('../../data/capital/a0','w',newline='')
csv_writer = csv.writer(out,dialect='excel')
 
 
for row in csv_reader:
	#输出的每一行是一个list,list中的每一个元素转换成了string类型
	print(row)
		csv_writer.writerow(row)

#encoding:utf-8
import csv
 
#读取csv文件方式1
csvFile = open('../../data/capital/2011-Q3-cabi-trip-history-data.csv','r')
reader = csv.reader(csvFile)
 
data = []
 
for item in reader:
#	print(item)
	data.append(item)
 
#print(data)
 
csvFile.close()
 
 
#读取csv文件方式2
with open("../../data/capital/2011-Q3-cabi-trip-history-data.csv",'r') as csvFile:
	#读取csv文件,返回的是迭代类型
	reader2 = csv.reader(csvFile)
	for item2 in reader2:
		print(item2)
csvFile.close()
 
 
#从列表写入csv文件
#设置newline,否则两行之间会空一行
csvFile2 = open('../../data/capital/0001.csv','w',newline='')
writer = csv.writer(csvFile2)
m = len(data)
for i in range(m):
	writer.writerow(data[i])
csvFile2.close()
 
 
#从字典写入csv文件
dic = {'张三':123,'李四':456,'王二娃':789}
csvFile3 = open('../../data/capital/0001.csv','w',newline='')
writer2 = csv.writer(csvFile3)
for key in dic:
	print(key)
#	writer2.writerow([key,dic[key]])
 
csvFile3.close()

#encoding:utf-8
'''
import pandas as pd
#任意的多组列表
a = [1,2,3]
b = [4,5,6]
#字典中的key值即为csv中的列名
dataFrame = pd.DataFrame({'a_name':a,'b_name':b})
#将DataFrame存储为csv,index表示是否显示行名,default=True
dataFrame.to_csv('0001.csv',index=False,sep='')
#pandas提供的读取csv的方法
data = pd.read_csv('test.csv')
'''
 
 
#===================================
#另一种方法:用csv包,一行一行写入
import csv
 
#python2可以用file替代open
with open('test.csv','w') as csvFile:
	writer = csv.writer(csvFile)
	#先写columns_name
	writer.writerow(["index","a_name","b_name"])
	#写入多行用writerows
	writer.writerows([[1,2,3],[0,1,2],[4,5,6]])
 
#用reder读取csv文件
with open('test.csv','r') as csvFile:
	reader = csv.reader(csvFile)
	for line in reader:
		print line

#encoding:utf-8
import csv
 
 
with open('test.csv') as csvFile:
	#readcsv = csv.reader(csvFile,delimiter='')
	readcsv = csv.reader(csvFile)
	#
	rows= [row for row in readcsv]
	for row in readcsv:
		rows= [row for row in reader]
		#print(row)#打印一行
		print(row[0])#打印一行中的某个cell
		print(row[0],row[1])#打印一行中的某个cell
 
print('=================')
 
with open('test.csv') as csvFile:
	readCSV = csv.reader(csvFile)
	cols1 = []
	cols2 = [] 
	cols3 = []
	for row in readCSV:
		col1 = row[0]	
		col2 = row[1]
		col3 = row[2]
		
		cols1.append(col1)
		cols2.append(col2)
		cols3.append(col3)
 
print cols1
print cols2
print cols3

#encoding:utf-8
import csv
 
#第一种方法:使用reader函数,接收一个可迭代的对象(比如csv文件),能返回一个生成器,就可以从其中解析出csv的内容.eg:下面的代码可以读取csv的全部内容,以行为单位
with open('test.csv','rb') as csvFile:
	reader = csv.reader(csvFile)
	rows = [row for row in reader]
 
print rows
 
 
print('===========')
 
#提取其中某一列可以使用下面的方法
with open('test.csv','rb') as csvFile:
	reader = csv.reader(csvFile)
	column = [row[1] for row in reader]
print column
 
 
 
print('======第二种方法======')
#第二种方法:使用DictReader,和reader函数类似,接收可迭代的对象,能返回一个可迭代的对象,能返回一个生成器,但是返回的每一个单元格都放在一个字典的值内,而这个字典的键则是这个单元格的标题.用下面的代码可以看到DictReader的结构:
with open('test.csv','rb') as csvFile:
	reader = csv.DictReader(csvFile)
	column = [row for row in reader]
print(column)
 
#使用CictReader读取csv的某一列,这样可以按照列的标题查询
with open('test.csv','rb') as csvFile:
	reader = csv.DictReader(csvFile)
	column = [row['a_name'] for row in reader]
print column

#encoding:utf-8
import csv
 
with open('test.csv','rb') as csvFile:
	reader = csv.reader(csvFile)
	for row in reader:
		print row
 
#向csv文件中写内容,这样写会把内容全部写到一个cell中
with open('test1.csv','wb') as csvFile:
	writer = csv.writer(csvFile,delimiter=' ',quotechar='|',quoting=csv.QUOTE_MINIMAL)
	writer.writerow(['a','4','5','6'])
	writer.writerow(['b','1','2','3'])
	writer.writerow(['c','9','8','7'])
	writer.writerow(['d','8','3','1'])
 
 
#向csv文件中写内容,下面的写法最终可以把每一列的内容放在一个cell中
with open('test2.csv','wb') as csvFile:
	writer = csv.writer(csvFile,dialect='excel')
	writer.writerow(['a','4','5','6'])
	writer.writerow(['b','1','2','3'])
	writer.writerow(['c','9','8','7'])
	writer.writerow(['d','8','3','1'])