I'm a new Python user.
I have a txt file that will be something like:
3,1,3,2,3
3,2,2,3,2
2,1,3,3,2,2
1,2,2,3,3,1
3,2,1,2,2,3
but may be less or more lines.
I want to import each line as a list.
I know you can do it as such:
filename = 'MyFile.txt'
fin=open(filename,'r')
L1list = fin.readline()
L2list = fin.readline()
L3list = fin.readline()
but since I don't know how many lines I will have, is there another way to create individual lists?
This question is related to
python
list
python-3.x
file-io
with open('path/to/file') as infile: # try open('...', 'rb') as well
answer = [line.strip().split(',') for line in infile]
If you want the numbers as int
s:
with open('path/to/file') as infile:
answer = [[int(i) for i in line.strip().split(',')] for line in infile]
Do not create separate lists; create a list of lists:
results = []
with open('inputfile.txt') as inputfile:
for line in inputfile:
results.append(line.strip().split(','))
or better still, use the csv
module:
import csv
results = []
with open('inputfile.txt', newline='') as inputfile:
for row in csv.reader(inputfile):
results.append(row)
Lists or dictionaries are far superiour structures to keep track of an arbitrary number of things read from a file.
Note that either loop also lets you address the rows of data individually without having to read all the contents of the file into memory either; instead of using results.append()
just process that line right there.
Just for completeness sake, here's the one-liner compact version to read in a CSV file into a list in one go:
import csv
with open('inputfile.txt', newline='') as inputfile:
results = list(csv.reader(inputfile))
Create a list of lists:
with open("/path/to/file") as file:
lines = []
for line in file:
# The rstrip method gets rid of the "\n" at the end of each line
lines.append(line.rstrip().split(","))
lines=[]
with open('file') as file:
lines.append(file.readline())
Source: Stackoverflow.com