Parsing a text file into a list in python

Question

I'm completely new to Python, and I'm trying to read in a txt file that contains a combination of words and numbers. I can read in the txt file just fine, but I'm struggling to get the string into a format I can work with.

import matplotlib.pyplot as plt
import numpy as np
from numpy import loadtxt

f= open("/Users/Jennifer/Desktop/test.txt", "r")

lines=f.readlines()

Data = []

list=lines[3]
i=4
while i<12:
        list=list.append(line[i])
        i=i+1

print list

f.close()

I want a list that contains all the elements in lines 3-12 (starting from 0), which is all numbers. When I do print lines[1], I get the data from that line. When I do print lines, or print lines[3:12], I get each character preceded by \x00. For example, the word "Plate" becomes: ['\x00P\x00l\x00a\x00t\x00e. Using lines = [line.strip() for line in f] gets the same result. When I try to put individual lines together in the while loop above, I get the error "AttributeError: 'str' object has no attribute 'append'."

How can I get a selection of lines from a txt file into a list? Thank you so much!!!

Edit: The txt file looks like this:

BLOCKS= 1 Plate: Phosphate Noisiness Assay 2000x 1.3 PlateFormat Endpoint Absorbance Raw FALSE 1 1 650 1 12 96 1 8
Temperature(¡C) 1 2 3 4 5 6 7 8 9 10 11 12
21.4 0.4977 0.5074 0.5183 0.5128 0.5021 0.5114 0.4993 0.5308 0.4837 0.5286 0.5231 0.5227
0.488 0.4742 0.5011 0.4868 0.4976 0.4845 0.4848 0.5179 0.4772 0.5363 0.5109 0.5197
0.4882 0.4913 0.4941 0.5188 0.4766 0.4914 0.495 0.5172 0.4826 0.5039 0.504 0.5451
0.4771 0.4875 0.523 0.4851 0.4757 0.4767 0.4918 0.5212 0.4742 0.5153 0.5027 0.5235
0.4474 0.4841 0.5193 0.4755 0.4649 0.4883 0.5165 0.5223 0.4799 0.5269 0.5091 0.5191
0.4721 0.4794 0.501 0.4467 0.4785 0.4792 0.4894 0.511 0.4778 0.5223 0.4888 0.5273
0.4122 0.4454 0.314 0.2747 0.4621 0.4416 0.3716 0.2534 0.4497 0.5778 0.2319 0.1038
0.4479 0.5368 0.3046 0.3115 0.4745 0.5116 0.3689 0.3915 0.4803 0.5209 0.1981 0.1062

~End Original Filename: 2013-08-06 Phosphate Noisiness; Date Last Saved: 8/6/2013 7:00:55 PM

Update I used this code:

f= open("/Users/Jennifer/Desktop/test.txt", "r")
file_list = f.readlines()

first_twelve = file_list[3:11]

data = [x.replace('\t',' ') for x in first_twelve]
data = [x.replace('\x00','') for x in data]
data = [x.replace(' \r\n','') for x in data]

print data

to get this result: [' 21.4 0.4977 0.5074 0.5183 0.5128 0.5021 0.5114 0.4993 0.5308 0.4837 0.5286 0.5231 0.5227 ', ' 0.488 0.4742 0.5011 0.4868 0.4976 0.4845 0.4848 0.5179 0.4772 0.5363 0.5109 0.5197 ', ' 0.4882 0.4913 0.4941 0.5188 0.4766 0.4914 0.495 0.5172 0.4826 0.5039 0.504 0.5451 ', ' 0.4771 0.4875 0.523 0.4851 0.4757 0.4767 0.4918 0.5212 0.4742 0.5153 0.5027 0.5235 ', ' 0.4474 0.4841 0.5193 0.4755 0.4649 0.4883 0.5165 0.5223 0.4799 0.5269 0.5091 0.5191 ', ' 0.4721 0.4794 0.501 0.4467 0.4785 0.4792 0.4894 0.511 0.4778 0.5223 0.4888 0.5273 ', ' 0.4122 0.4454 0.314 0.2747 0.4621 0.4416 0.3716 0.2534 0.4497 0.5778 0.2319 0.1038 ', ' 0.4479 0.5368 0.3046 0.3115 0.4745 0.5116 0.3689 0.3915 0.4803 0.5209 0.1981 0.1062 ']

Which is (correct me if I'm wrong, very new to Python!) a list of lists, which I should be able to work with. Thank you so much to everyone who responded!!!

Answer 1

When you write the code lines = f.readlines() a list of lines is being return to you. When you then say lines[3], you're getting the 3rd line. Thats why you're ending up with individual characters.

All you need to do is say

files = open("Your File.txt")

file_list =  files.readlines()

first_twelve = file_list[0:12] #returns a list with the first 12 lines

Once you've got the first_twelve array you can do whatever you want with it.

To print each line you would do:

for each_line in first_twelve:
    print each_line

That should work for you.