How to read and assign to variable/list multiple text files?

Question

I have multiple files, let's say data{1..10}.txt in folder data/

I need to read these files into python environment for further use, example code i have in mind is:


chr_list = []

x = 0
for item in range(10):
    datafile="data/data"+str(i+1)+".txt"
    chr_list[x] = open(datafile, "r")
    x += 1

The expected outcome would be

print(chr_list[0])

#prints out content of file data/data1.txt

This code doesn't work even after correcting all possible errors. Thus, i would like to see some examples on how to reach my desired outcome.

You must actually read the file content: chr_list.append(open(datafile, "r").read()) — Thierry Lathuille
– Thierry Lathuille, Commented Dec 22, 2019 at 13:40
The code still brings out the same errors, so i assume there has to be a deeper mistake in a code — juststuck
– juststuck, Commented Dec 22, 2019 at 13:42
Sorry, the as the list was originally empty, you must append to it. I updated my comment. — Thierry Lathuille
– Thierry Lathuille, Commented Dec 22, 2019 at 13:45
Please take care to always include the complete error traceback in your question when you have an error, it makes it easier to spot the problems in your code. — Thierry Lathuille
– Thierry Lathuille, Commented Dec 22, 2019 at 13:48

Ed Ward · Accepted Answer · 2019-12-22 13:43:02Z

3

As Thierry Lathuille pointed out, to get the contents of the file you have to actually call the read method. Without calling this, you will have a list of open files, not their contents. You can also shorten your code by using the for-loop counter instead of incrementing your own value.

New code:

chr_list = []

for x in range(10):
    datafile="data/data"+str(i+1)+".txt"
    chr_list.append(open(datafile).read())

EDIT:

The error comes from the fact that you can't add items to a list by referencing a new index - you have to use the append method.

EDIT 2:

You can also cut down your code by using list comprehensions:

chr_list = [open("data/data"+str(i+1)+".txt").read() for i in range(10)]

answered Dec 22, 2019 at 13:43

Ed Ward

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2 Comments

juststuck Over a year ago

Yeah, both answers solved it. How can i mark both as correct?

Ed Ward Over a year ago

I don't think you can... Does yganalyst's answer actually produce a list of the contents?

yganalyst · Accepted Answer · 2019-12-22 13:43:09Z

1

It can do with a dictionary not a list.

chr_list = {}

x = 0
for i in range(10):
    datafile="data/data"+str(i+1)+".txt"
    chr_list[x] = open(datafile, "r")
    x += 1

chr_list[0]

Or

chr_list = {}

for i in range(10):
    name = "data" + str(i+1)
    chr_list[name] = open("data/"  + name + ".txt", "r")

chr_list['data1']

answered Dec 22, 2019 at 13:43

yganalyst

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5 Comments

juststuck Over a year ago

Changing [] to {} fixes an issue.

Ed Ward Over a year ago

This code won't currently add the contents of the files to the list/dictionary... It will make a list of file objects.

juststuck Over a year ago

When calling chr_list[0] it gives the content of the file though, what am i missing?

Ed Ward Over a year ago

chr_list[0] isn't an index when using dictionaries in this way... use chr_list['data1'] instead... Also, using this code, chr_list['data1'] gives <_io.TextIOWrapper name='data1.txt' mode='r' encoding='cp1252'>, not the content of data1.txt...

AMC Over a year ago

You’re not actually reading the contents of the file, nor are you properly handling it using a context manager.

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