This is the code:
for(int i=1; i<=10; ++i)
for(int j=1; j<=10; ++j)
cin >> G[i][j];
This is a two dimension array G, and I want to store the data from G[1][1], not from zero.
How to implement this code in python?
5 Answers
for i in xrange(1, 11):
for j in xrange(1, 11):
G[i][j] = raw_input()
or a more pythonic way, assuming G is empty before your loops:
G = [[raw_input() for j in xrange(1, 11)] for i in xrange(1, 11)]
(doesn't work, those lists would have the first value at element 0 which is not what the OP wants)
4 Comments
hago
what's G's type? if it's a list or tuple, it's still 0-based, which may not be what he wants.
jamylak
also remove that ugly semicolon!
ThiefMaster
@ott--: The end value is exclusive.
range(1, 11) == [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
starcorn
the first one is more readable than the second one. Or maybe I'm not used to pythonic ways...
>>> import random
>>> G = [[0]*11 for _ in range(11)]
>>> G
[[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]
>>> for i in range(1, 11):
for j in range(1, 11):
G[i][j] = random.randint(1,10)
>>> G
[[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 7, 8, 10, 5, 7, 9, 8, 10, 8, 3], [0, 7, 9, 7, 7, 6, 6, 10, 2, 8, 9], [0, 10, 6, 3, 7, 10, 7, 9, 6, 1, 7], [0, 5, 7, 1, 10, 3, 3, 1, 2, 5, 6], [0, 7, 3, 5, 4, 4, 2, 10, 10, 8, 1], [0, 10, 3, 3, 5, 4, 4, 2, 5, 3, 1], [0, 6, 6, 6, 6, 2, 3, 8, 1, 6, 4], [0, 7, 8, 5, 8, 1, 9, 5, 5, 2, 9], [0, 3, 2, 4, 1, 1, 4, 7, 7, 5, 5], [0, 3, 4, 10, 1, 2, 5, 3, 10, 9, 7]]
random.randint was used in place of input() or raw_input() to show that this works.
Comments
Initialising G:
G = [[0 for i in xrange(11)] for i in xrange(11)]
or G = [[0]*11]*11
Populating G:
for i in xrange(10):
for j in xrange(10):
G[i+1][j+1] = int(raw_input())
If you want to construct G in-place, you could do it with a nested list comprehension similar to the initialisation
9 Comments
warvariuc
@PreetKukreti, try:
>>> G = [[0]*5]*5 >>> G[0][0]=2 >>> G
Kien Truong
G = [[0]*11]*11 is the wrong way to initialize G. The same object is shared between G[i][0]. When you modify G[0][0], it'll also modify all G[i][0] value.
Preet Kukreti
@warwaruk yep you are right thanks, 11 references to the same list. Not sure how I missed that
warvariuc
@PreetKukreti, this is classical :)
jamylak
I thought the same thing so i did mine correctly then when i saw @Preet's code i thought that was quicker but forgot to test it...
|
Using dictionaries:
G = {}
for i in xrange(1, 11):
G[i] = {}
for j in xrange(1, 11):
G[i][j] = raw_input()
Using lists (but starting indexes from 0):
G = []
for _ in xrange(1, 11):
row = []
G.append(row)
for _ in xrange(1, 11):
row.append(raw_input())
Comments
If readability counts, this is also quite readable
G=[[0]*11 for _ in range(11)]
for (i,j) in itertools.product(range(1,11),range(1,11)):
while True:
try:
G[i][j]=int(raw_input())
break
except ValueError:
None
cin >>is C++ not C. Array of what: characters? integers? strings?[[int(raw_input()) for _ in range(0, 11)] for _ in range (0, 11)]but I don't really get the 'index from 1' partG[1][1]", when the array will start at 0 no matter what you "want", and[10]will not be a valid index unless the array size is at least[11]? C++ doesn't care about what you want; it cares only about what you tell it to do.