如何一行一行地读取文件，然后打印该行，如果它包含在Python中有一个值的范围的字符串？ [英] How to read a file line by line, then print the line if it contains a string with a range of value in Python?

问题描述

我有一个文本文件，有一行行包含如下字符串：

 AA ,, BB，2014-02-06,0,0 | CC ,, DD， 2014-02-27,0,0 | EE ,, FF，2014-02-04,1,1＃GG＃USD＃true#Total：USD＃1638.93＃
  

（USD前有一堆文字，每行不同）。

我试着这样做：

 打开（'out_put_usjfk50.csv'，'rb' 
 reader = csv.reader（f，delimiter ='＃'）
读取器中的行：
 amount = float（row [5]）
如果amount <= 800 ：
 print row 
 elif amount is None：
 pass 
  

但我得到了相同的错误： ValueError：无法将字符串转换为浮动：

如何通过每一行来检查整数值（是字符串的一部分），然后打印行，如果它小于，比如USD1500？

解决方案

您有一个CSV文件;请使用 csv 模块 ：

  import csv 
 
 with open（'filename.csv'，'rb'）as f ：
 reader = csv.reader（f，delimiter ='＃'）
读取器中的行：
  

新的每个 row object是一个字符串列表;

说明'1638.93'列是第8列， d使用（使用基于0的索引的Python）：

  amount = float（row [7]）
  

现在你有一个浮点数字，你可以测试它：

  with open（'filename.csv'，'rb'）as f：
 reader = csv.reader（f，delimiter ='＃'） 
 for row in reader：
 amount = float（row [7]）
如果amount <= 1500：
打印行
  

I'm a newbie with Python 2.7 and I'm still trying to get the hang of it.

I have a text file with a row of lines that contain strings like this:

"AA,,BB,2014-02-06,0,0|CC,,DD,2014-02-27,0,0|EE,,FF,2014-02-04,1,1"#"GG"#"USD"#"true"#Total : USD#1638.93#

(There's a bunch of text before 'USD' that varies with each line.)

I tried doing this:

with open('out_put_usjfk50.csv', 'rb') as f:
    reader = csv.reader(f, delimiter='#')
    for row in reader:
        amount = float(row[5])
        if amount <= 800:
            print row
        elif amount is None:
            pass

but I got the same error: ValueError: could not convert string to float:

I'm stumped. How do I go through each line to check for the integer value (that's part of a string), and then print the line(s) if it's less than, say, USD1500? I'd appreciate it if someone can point me to the right direction!

解决方案

You have a CSV file; use the csv module:

import csv

with open('filename.csv', 'rb') as f:
    reader = csv.reader(f, delimiter='#')
    for row in reader:

New each row object is a list of strings; each string representing a column in your file.

Say the '1638.93' column is column 8, then you'd use (with Python using 0-based indexing):

amount = float(row[7])

Now you have a floating point number from that string, and you can test against it:

with open('filename.csv', 'rb') as f:
    reader = csv.reader(f, delimiter='#')
    for row in reader:
        amount = float(row[7])
        if amount <= 1500:
            print row

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