I am creating a program that reads a file and if the first line of the file is not blank, it reads the next four lines. Calculations are performed on those lines and then the next line is read. If that line is not empty it continues. However, I am getting this error:

ValueError: invalid literal for int() with base 10: ''.

It is reading the first line but can’t convert it to an integer.

What can I do to fix this problem?

The code:

file_to_read = raw_input("Enter file name of tests (empty string to end program):")
try:
    infile = open(file_to_read, 'r')
    while file_to_read != " ":
        file_to_write = raw_input("Enter output file name (.csv will be appended to it):")
        file_to_write = file_to_write + ".csv"
        outfile = open(file_to_write, "w")
        readings = (infile.readline())
        print readings
        while readings != 0:
            global count
            readings = int(readings)
            minimum = (infile.readline())
            maximum = (infile.readline())

Just for the record:

>>> int('55063.000000')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: '55063.000000'

Got me here…

>>> int(float('55063.000000'))
55063.0

Has to be used!

The following are totally acceptable in python:

• passing a string representation of an integer into int
• passing a string representation of a float into float
• passing a string representation of an integer into float
• passing a float into int
• passing an integer into float

But you get a ValueError if you pass a string representation of a float into int, or a string representation of anything but an integer (including empty string). If you do want to pass a string representation of a float to an int, as @katyhuff points out above, you can convert to a float first, then to an integer:

>>> int('5')
5
>>> float('5.0')
5.0
>>> float('5')
5.0
>>> int(5.0)
5
>>> float(5)
5.0
>>> int('5.0')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: '5.0'
>>> int(float('5.0'))
5

Pythonic way of iterating over a file and converting to int:

for line in open(fname):
   if line.strip():           # line contains eol character(s)
       n = int(line)          # assuming single integer on each line

What you’re trying to do is slightly more complicated, but still not straight-forward:

h = open(fname)
for line in h:
    if line.strip():
        [int(next(h).strip()) for _ in range(4)]     # list of integers

This way it processes 5 lines at the time. Use h.next() instead of next(h) prior to Python 2.6.

The reason you had ValueError is because int cannot convert an empty string to the integer. In this case you’d need to either check the content of the string before conversion, or except an error:

try:
   int('')
except ValueError:
   pass      # or whatever

I found a work around. Python will convert the number to a float. Simply calling float first then converting that to an int will work: output = int(float(input))

The reason is that you are getting an empty string or a string as an argument into int. Check if it is empty or it contains alpha characters. If it contains characters, then simply ignore that part.

The reason you are getting this error is that you are trying to convert a space character to an integer, which is totally impossible and restricted.And that’s why you are getting this error.

Check your code and correct it, it will work fine

So if you have

floatInString = '5.0'

You can convert it to int with floatInInt = int(float(floatInString))

You’ve got a problem with this line:

while file_to_read != " ":

This does not find an empty string. It finds a string consisting of one space. Presumably this is not what you are looking for.

Listen to everyone else’s advice. This is not very idiomatic python code, and would be much clearer if you iterate over the file directly, but I think this problem is worth noting as well.

Please test this function (split()) on a simple file. I was facing the same issue and found that it was because split() was not written properly (exception handling).

    readings = (infile.readline())
    print readings
    while readings != 0:
        global count
        readings = int(readings)

There’s a problem with that code. readings is a new line read from the file – it’s a string. Therefore you should not compare it to 0. Further, you can’t just convert it to an integer unless you’re sure it’s indeed one. For example, empty lines will produce errors here (as you’ve surely found out).

And why do you need the global count? That’s most certainly bad design in Python.

This could also happen when you have to map space separated integers to a list but you enter the integers line by line using the .input(). Like for example I was solving this problem on HackerRank Bon-Appetit, and the got the following error while compiling

So instead of giving input to the program line by line try to map the space separated integers into a list using the map() method.

I am creating a program that reads a file and if the first line of the file is not blank, it reads the next four lines. Calculations are performed on those lines and then the next line is read.

Something like this should work:

for line in infile:
    next_lines = []
    if line.strip():
        for i in xrange(4):
            try:
                next_lines.append(infile.next())
            except StopIteration:
                break
    # Do your calculation with "4 lines" here

I was getting similar errors, turns out that the dataset had blank values which python could not convert to integer.

I got into the same issue when trying to use readlines() inside for loop for same file object… My suspicion is firing readling() inside readline() for same file object caused this error.

Best solution can be use seek(0) to reset file pointer or Handle condition with setting some flag then create new object for same file by checking set condition….

I recently came across a case where none of these answers worked. I encountered CSV data where there were null bytes mixed in with the data, and those null bytes did not get stripped. So, my numeric string, after stripping, consisted of bytes like this:

\x00\x31\x00\x0d\x00

To counter this, I did:

countStr = fields[3].replace('\x00', '').strip()
count = int(countStr)

…where fields is a list of csv values resulting from splitting the line.

This seems like readings is sometimes an empty string and obviously an error crops up. You can add an extra check to your while loop before the int(readings) command like:

while readings != 0 | readings != '':
    global count
    readings = int(readings)

I had hard time figuring out the actual reason, it happens when we dont read properly from file. you need to open file and read with readlines() method as below:

with open('/content/drive/pre-processed-users1.1.tsv') as f:
    file=f.readlines()

It corrects the formatted output

your answer is throwing errors because of this line

readings = int(readings)

1. Here you are trying to convert a string into int type which is not base-10. you can convert a string into int only if it is base-10 otherwise it will throw ValueError, stating invalid literal for int() with base 10.