Importing Large Tab-Delimited. Txt File into Python

First, you are loading it into a dictionary, which is not going to get the list of lists that you want.

It's dead simple to use the CSV module to generate a list of lists like this:

import csv
with open(path) as f:
    reader = csv.reader(f, delimiter="\t")
    d = list(reader)
print d[0][2] # 248

That would give you a list of lists of strings, so if you wanted to get numbers, you'd have to convert to int.

That said, if you have a large array (or are doing any kind of numeric calculations), you should consider using something like NumPy or pandas. If you wanted to use NumPy, you could do

import numpy as np
d = np.loadtxt(path, delimiter="\t")
print d[0,2] # 248

As a bonus, NumPy arrays allow you to do quick vector/matrix operations. (Also, note that d[0][2] would work with the NumPy array too).

Try this:

d = []
with open(sourcefile,'rb') as source:
    for line in source:
        fields = line.split('\t')
        d.append(fields)

print d[0][1] will print 266.

print d[0][2] (remember your arrays are 0-based) will print 248.

To output the data in the same format as your input:

for line in d:
    print "\t".join(line)

Use Pandas Library:-

import pandas as pd
dataset = pd.read_csv(path,delimiter="\t")
dataset.iloc[0,2]

Not sure how to make print(d[0,3]) output 248, but this will make print(d[0][3]) output 248. First StackOverflow answer so IDK how show that the last two lines in my code block are actually just one long line.

import csv

Text_Input = r"<.txt file>"  
listoflists= []

with open(Text_Input) as txtfile:
    reader = csv.reader(txtfile)

    for row in reader:
        listoflists.append([int(row[0].split()[i]) for i in 
        range(len(row[0].split()))])