How do I take numbers from a file and read them as integers if they have headings in python?

Question

I have a file that has a bunch of numbers, but there are headings that are keeping me from doing much. The file looks like this:

x: 
1 2 3 4 

f: 
5 6 7 8

h:
9 10 11 12 13

so I have this program which i believe will help me access the numbers but I get an error message about it.

filename = input('file: ')
f = open(filename, 'r')
output=[]
w, h = map(int,lines.split())
x=[]
for i, line in enumerate(f):
    if i == h:
        break
    x.append(map(int,line.split()[:w]))
output.append(x)

So i tried striping the headers, but I get an error message about it being a string and such.

filename = input('file: ')
f = open(filename, 'r')
output=[]
func = f.readline()
lines = func.strip('x').strip('f').strip('h').split()
w, h = map(int,lines.split())
x=[]
for i, line in enumerate(f):
    if i == h:
         break
    x.append(map(int,line.split()[:w]))
output.append(x)

any advice?

Answer 1

Example

filename = input('filename: ')

with open(filename, 'r') as f:
    for line in f: # line one-by-one
        line = line.strip() # strip to check empty lines
        if line: # skip empty lines
            elements = line.split()
            print(elements[2]) # [column]

or

filename = input('filename: ')

# get not empty lines
lines = []

with open(filename, 'r') as f:
    for line in f: # 
        line = line.strip() # strip to check empty lines
        if line: # skip empty lines
            elements = line.split()
            lines.append(elements)

# work with lines one-by-one

for line in lines: # 
    print(line[2]) # [column]

# direct access to any element 

print(lines[1][2]) # [row][column]