[转载]Python csv文件 相关操作

2020-08-26  本文已影响0人  AeroZ

https://www.cnblogs.com/liangxiyang/p/11272155.html

import csv
with open('/f.CSV', 'r') as f:
    reader = csv.reader(f)
    print(type(reader))
    '''获取每一行'''
    # for row in reader:
    #     print(row)
    '''获取每一行'''
    # result = list(reader)
    # print(result[0])
    '''获取某一列'''
    for i in reader:
        print(i[0])

Python对CSV文件的处理
https://cloud.tencent.com/developer/article/1357970

Python处理CSV与List的转换

作者:新手村的0级玩家
链接:https://www.jianshu.com/p/61b45b6b36aa
1.读取CSV文件到List

def readCSV2List(filePath):
    try:
        file=open(filePath,'r',encoding="gbk")# 读取以utf-8
        context = file.read() # 读取成str
        list_result=context.split("\n")#  以回车符\n分割成单独的行
        #每一行的各个元素是以【,】分割的,因此可以
        length=len(list_result)
        for i in range(length):
            list_result[i]=list_result[i].split(",")
        return list_result
    except Exception :
        print("文件读取转换失败,请检查文件路径及文件编码是否正确")
    finally:
        file.close();# 操作完成一定要关闭

2.将List写入到CSV文件中

def writeList2CSV(myList,filePath):
    try:
        file=open(filePath,'w')
        for items in myList:
            for item in items:
                file.write(item)
                file.write(",")
            file.write("\n") 
    except Exception :
        print("数据写入失败,请检查文件路径及文件编码是否正确")
    finally:
        file.close();# 操作完成一定要关闭

另一篇文章:使用python读取csv并转化成list of list的方法
https://blog.csdn.net/birdflyinhigh/article/details/79685019

利用python转置csv文件
https://blog.csdn.net/baidu_41217766/article/details/96271603

    df = pd.read_csv(file)
    df.values
    data = df.as_matrix()
    data = list(map(list,zip(*data)))
    data = pd.DataFrame(data)
    data.to_csv('dataset/'+file,header=0,index=0)

Python之str型转成int型

https://www.cnblogs.com/fallenmoon/p/7200947.html

def fn(x,y):
    return x*10+y

def char2num(s):
    return {'0':0, '1':1, '2':2, '3':3, '4':4, '5':5, '6':6, '7':7, '8':8, '9':9}[s]  # 特别注意这里,后面还有个 [s]

print(type(reduce(fn, map(char2num, '1738785'))))
print(reduce(fn, map(char2num, '1738785')))
from functools import reduce

def str2int(s):
    def fn(x,y):
        return x*10+y
    def char2num(s):
        return {'0':0, '1':1, '2':2, '3':3, '4':4, '5':5, '6':6, '7':7, '8':8, '9':9}[s]
    return reduce(fn,map(char2num,s))

print(str2int('365779'))
print(type(str2int('365779')))
'''str转int'''
from functools import reduce
def str2int(s):
    return reduce(lambda x,y:x*10+y, map(lambda s:{'0':0, '1':1, '2':2, '3':3, '4':4, '5':5, '6':6, '7':7, '8':8, '9':9,}[s], s))

python 一行语句实现if else
https://blog.csdn.net/weixin_44255799/article/details/100945329

value_when_true if condition_is_ture else value_when_condition_is_false

python利用numpy模块读取csv文件

https://blog.csdn.net/u012413551/article/details/87890989

python 借助numpy保存数据为csv格式的实现方法

https://www.jb51.net/article/143139.htm

借助numpy可以把数组或者矩阵保存为csv文件,也可以吧csv文件整体读取为一个数组或矩阵。

1. csv ==> matrix

import numpy
my_matrix = numpy.loadtxt(open("D:\\test.csv","rb"), delimiter=",", skiprows=0)

2. matrix ==> csv

import numpy
numpy.savetxt("new.csv", my_matrix, delimiter=',')
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