overlapping and enumerate in python - numpy

Question

Given two files
We need to find of all the number overlapping the data from both the file which are prime.
For check the prime number we need to develop a function called check_prime and use the same.
My code :
import math
def is_prime(num):
if num == 1:
return False
if num == 2:
return True
for i in range(2,int(math.sqrt(num))+1):
if num % i == 0:
return False
return True
one = []
theFile = open("One.txt", "r")
array = []
for val in theFile:
array.append(val)
print(array)
theFile = open("Two.txt", "r")
array1 = []
for val in theFile:
array1.append(val)
print(array1)
for i in array:
one.append(i)
print(one)

Answer 1

You are almost there but here are the missing bits in your code:
1) Reading from the files
To avoid writing twice the same code to open both files, and to handle more than two files, we can loop through the file names instead of opening each one separately
So instead of:
theFile = open("One.txt", "r")
#[...]
theFile = open("Two.txt", "r")
We could use:
file_names = ['One.txt', 'Two.txt']
for i in file_names:
theFile = open(i, "r")
2) Extracting the numbers from the files
Then you extract the values in the text file. The list of numbers in each file gets imported as a list containing a string with numbers in it.
So there are 2 things we need to do:
1) extract the string from the list
2) read each string number in the list separated by commas.
If you do:
for val in theFile:
array.append(val)
You will only append one list containing one string to your array.
In your code, you create two lists: array and array1 but then only loop through the array list which puts in your one list only the data from the array list, not using array1 at all. Nothing to worry about, I also get confused sometimes between array[1] and array1 if I name several lists ending in 1,2,3.
So instead we could do:
for val in theFile:
array = array + val.split(",")
We use + because we want all the number-strings in one single list and not one list containing several lists (you can try to replace this by: array = array.append(val.split(",")) and you'll see you get a list containing lists but what we want is all number-strings from all files in one single list so better to concatenate the elements in the lists into one single list.
Now that you have your array list that contains all string-numbers from your text files, you need to transform them into integers so you can run your excellent is_prime function.
So we create a second list that I've called array2 where we will store the string-numbers as integers and not as strings.
The final output that you want is a list of the unique prime numbers in both text files, so we check that the number is not already in array2 before appending it.
for nbrs in array:
if int(nbrs) not in array2:
array2.append(int(nbrs))
Almost there! You've already done the rest of the work from there on:
You need to pass all the unique numbers in array2 to your is_prime function to check whether they are prime or not.
We store the result of the is_prime function (True or False) into the list is_nbr_prime.
is_nbr_prime = []
for i in array2:
is_nbr_prime.append(is_prime(i))
Now, because you want to return the number themselves, we need to find the indexes of the prime numbers to extract them from array2, which are the indexes of the True values in is_nbr_prime:
idx = [i for i, val in enumerate(is_nbr_prime) if val] #we get the index of the values that are True in is_nbr_prime list
unique_prime_nbrs = [array2[i] for i in idx] # we pass the index to array2 containing the list of unique numbers to take out only prime numbers.
That's it, you have your unique prime numbers in the list unique_prime_nbrs .
If we put all the steps together into two functions, the final code is:
def is_prime(num):
if num == 1:
return False
if num == 2:
return True
for i in range(2,int(math.sqrt(num))+1):
if num % i == 0:
return False
return True
def check_prime(file_names):
array = []
array2 = []
for i in file_names:
theFile = open(i, "r")
for val in theFile:
array = array + val.split(",")
for nbrs in array:
if int(nbrs) not in array2:
array2.append(int(nbrs))
is_nbr_prime = []
for i in array2:
is_nbr_prime.append(is_prime(i))
idx = [i for i, val in enumerate(is_nbr_prime) if val]
unique_prime_nbrs = [array2[i] for i in idx]
return unique_prime_nbrs
To call the function, we need to pass a list of file names, for instance:
file_names = ['One.txt', 'Two.txt']
unique_prime_nbrs = check_prime(file_names)
print(unique_prime_nbrs)
[5, 7, 13, 17, 19, 23]

Answer 2

There is a bunch of stuff you need to do:
When reading the text from the input files, convert it to integers before storing anywhere.
Instead of making array a list, make it a set. This will enable testing membership in much shorter time.
Before storing a values from the first file in array, check if it is a prime, using the is_prime function you wrote.
When reading the integers from the second file, before adding the values to array1, test if they are already in array. No need to heck for prime-ness, because array would already contain only primes.
Finally, before outputting the values from array1 you would need to convert them back to strings, and use the join string method to join them with separating commas.
So, get to it.