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From: Pramod on 11 Aug 2010 14:43
Hi

I want to know the how we input values into the matrix (N*N size)
from keyboard in python,

Here I wrote Matrix programe in C++


This asks values from key board and print on the console N*N matrix ;




Thanks in advance ....


#include<iostream>
using namespace std;
int main()
{
double **a;
int i,j,n;
cout<<"Enter size of the matrix\n";
cin>>n;
for(i=0;i<n;i++){
for(j=0;j<n;j++)
a[i][j] = random();
//or
//cin>>a[i][j];
cout<<endl;
}
for(i=0;i<n;i++){
for(j=0;j<n;j++)
cout<<a[i][j]<<"\t";
cout<<endl;
}
delete [] a;
}
From: Chris Rebert on 11 Aug 2010 15:06
On Wed, Aug 11, 2010 at 11:43 AM, Pramod <pramo4d(a)gmail.com> wrote:
> Hi
>
>   I want to know the how we input values into the matrix (N*N size)
> from keyboard in python,
>
> Here I wrote Matrix programe in C++
>
> This  asks values from key board and print on the console N*N matrix ;
>
> Thanks in advance ....
>
>
> #include<iostream>
> using namespace std;
> int main()
> {
>        double **a;
>        int i,j,n;
>        cout<<"Enter size of the matrix\n";
>        cin>>n;
>                for(i=0;i<n;i++){
>                for(j=0;j<n;j++)
>                        a[i][j] = random();
> //or
>                //cin>>a[i][j];
>                cout<<endl;
>        }
>        for(i=0;i<n;i++){
>                for(j=0;j<n;j++)
>                        cout<<a[i][j]<<"\t";
>                cout<<endl;
>        }
>        delete [] a;
> }

from random import random
from sys import exit

while True:
try:
N = int(raw_input("Enter size of the matrix: "))
except ValueError:
print "Invalid input. Try again."
except EOFError:
exit(1)
else:
break

a = [[random() for j in xrange(N)] for i in xrange(N)]
stringified = "\n".join("\t".join(row) for row in a)
print stringified


If you're doing serious work with matrices, look at the NumPy package.

Cheers,
Chris
--
http://blog.rebertia.com
From: MRAB on 11 Aug 2010 15:08
Pramod wrote:
> Hi
>
> I want to know the how we input values into the matrix (N*N size)
> from keyboard in python,
>
> Here I wrote Matrix programe in C++
>
>
> This asks values from key board and print on the console N*N matrix ;
>
[snip]

Read from the keyboard using raw_input() (in Python 2, or input() in
Python 3) and convert to float.

Incidentally, your C++ program doesn't allocate the array.

From: Chris Rebert on 11 Aug 2010 17:13
On Wed, Aug 11, 2010 at 12:06 PM, Chris Rebert <clp2(a)rebertia.com> wrote:
> On Wed, Aug 11, 2010 at 11:43 AM, Pramod <pramo4d(a)gmail.com> wrote:
>> Hi
>>
>>   I want to know the how we input values into the matrix (N*N size)
>> from keyboard in python,
>>
>> Here I wrote Matrix programe in C++
>>
>> This  asks values from key board and print on the console N*N matrix ;
>>
>> Thanks in advance ....
>>
>>
>> #include<iostream>
>> using namespace std;
>> int main()
>> {
>>        double **a;
>>        int i,j,n;
>>        cout<<"Enter size of the matrix\n";
>>        cin>>n;
>>                for(i=0;i<n;i++){
>>                for(j=0;j<n;j++)
>>                        a[i][j] = random();
>> //or
>>                //cin>>a[i][j];
>>                cout<<endl;
>>        }
>>        for(i=0;i<n;i++){
>>                for(j=0;j<n;j++)
>>                        cout<<a[i][j]<<"\t";
>>                cout<<endl;
>>        }
>>        delete [] a;
>> }
>
> from random import random
> from sys import exit
>
> while True:
>    try:
>        N = int(raw_input("Enter size of the matrix: "))
>    except ValueError:
>        print "Invalid input. Try again."
>    except EOFError:
>        exit(1)
>    else:
>        break
>
> a = [[random() for j in xrange(N)] for i in xrange(N)]
> stringified = "\n".join("\t".join(row) for row in a)
> print stringified

Should have prefaced that with an "untested" disclaimer.
Make that:
stringified = "\n".join("\t".join(str(cell) for cell in row) for row in a)

- Chris
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