How to compute numbers in each line of a file python? - python-3.x

Question

In my file, I have in each line numbers that are between 0 and 256:
20
123
125
109
175
108
210
74
127
86
172
128
187
131
183
230
132
77
30
177
64
60
211
112
79
45
I would like to compute how many each number is repeated in this file:
with open('file', 'w') as f_sb_out:
for i in range(256):
total = sum(str(i))
print('Numre of repetition of '+str(i)+'is', str(total))

Answer 1

This is certainly not the best way of doing it in terms of error handling, but it meets your basic requirements.
# Declare dict for counts
numCount = dict()
with open('file.txt', 'r') as f_sb_out: # Need to change the form to read, not write
line = f_sb_out.readline() # Read the first line
while line: # Loop through each line
line = f_sb_out.readline()
line = line.strip() # Strip any whitespace on either end
if line == '': # Skip any whitespace lines
continue
if line in numCount:
numCount[line] = numCount[line] + 1 # Increment the counter
else:
numCount[line] = 1 # Start a new counter
# Print the counts
for num in numCount:
print "The number " + num + " appeared "+ str(numCount[num]) + " time(s)."
Given your file, it produces:
The number 210 appeared 1 times.
The number 211 appeared 1 times.
The number 60 appeared 1 times.
The number 132 appeared 1 times.
The number 131 appeared 1 times.
The number 64 appeared 1 times.
The number 112 appeared 1 times.
The number 177 appeared 1 times.
The number 175 appeared 1 times.
The number 230 appeared 1 times.
The number 172 appeared 1 times.
The number 79 appeared 1 times.
The number 86 appeared 1 times.
The number 45 appeared 1 times.
The number 183 appeared 1 times.
The number 187 appeared 1 times.
The number 77 appeared 1 times.
The number 108 appeared 1 times.
The number 109 appeared 1 times.
The number 125 appeared 1 times.
The number 127 appeared 1 times.
The number 128 appeared 1 times.
The number 74 appeared 1 times.
The number 30 appeared 1 times.
The number 123 appeared 1 times.

Answer 2

Create a counter dictionary and append the lines to it as you read over them. Once you finished you can access the key/values using counter.items()
from collections import Counter
cntr = Counter()
with open('numbers.txt', 'r') as file_in:
for line in file_in:
cntr[line.rstrip()] += 1
for k, v in cntr.items():
print('Numre of repetitions of %s: is %s' % (k, v))
> Numre of repetitions of 1: is 4
> Numre of repetitions of 3: is 3
> Numre of repetitions of 2: is 2
The input numbers.txt file contains:
1
2
3
2
3
3
1
1
1

Answer 3

Checking the counts of your numbers is super easy if you use the collections module. In it, there is a class named Counter that can count any hashable object you can throw at it. In this case, you can give it strings or numbers without a problem. You will need the latest version of Python to use the f strings demonstrated here:
#! /usr/bin/env python3
import collections
def main():
with open('numbers.txt', 'rt') as file:
counts = collections.Counter(map(int, file))
for key, value in sorted(counts.items()):
print(f'{key!r} repeats {value!s} times.')
if __name__ == '__main__':
main()