Python: list comprehension with boolean as return value
1
B is a quadratic matrix of size k.
I tried the following code
if [x for x in range(k) if B[x,1] == 1]:
to get:
For the first x in range(k-1), for which B[x,1] == 1, stop the for-loop and return true, such that the if-statement can be executed. If there is no such x, then return false and go on in the following code.
python python-3.x for-loop if-statement list-comprehension
asked Nov 12 '18 at 16:11
user4309user4309
133
add a comment |
1
B is a quadratic matrix of size k.
I tried the following code
if [x for x in range(k) if B[x,1] == 1]:
to get:
For the first x in range(k-1), for which B[x,1] == 1, stop the for-loop and return true, such that the if-statement can be executed. If there is no such x, then return false and go on in the following code.
python python-3.x for-loop if-statement list-comprehension
asked Nov 12 '18 at 16:11
user4309user4309
133
2
What's aquadratic matrix of size k? Can you provide a Minimal, Complete, and Verifiable example?
– jpp
Nov 12 '18 at 16:12
Use list comprehension only if you're interested in creating a list.
– Austin
Nov 12 '18 at 16:13
add a comment |
1
1
1
B is a quadratic matrix of size k.
I tried the following code
if [x for x in range(k) if B[x,1] == 1]:
to get:
For the first x in range(k-1), for which B[x,1] == 1, stop the for-loop and return true, such that the if-statement can be executed. If there is no such x, then return false and go on in the following code.
python python-3.x for-loop if-statement list-comprehension
asked Nov 12 '18 at 16:11
user4309user4309
133
B is a quadratic matrix of size k.
I tried the following code
if [x for x in range(k) if B[x,1] == 1]:
to get:
For the first x in range(k-1), for which B[x,1] == 1, stop the for-loop and return true, such that the if-statement can be executed. If there is no such x, then return false and go on in the following code.
python python-3.x for-loop if-statement list-comprehension
python python-3.x for-loop if-statement list-comprehension
asked Nov 12 '18 at 16:11
user4309user4309
133
asked Nov 12 '18 at 16:11
user4309user4309
133
asked Nov 12 '18 at 16:11
user4309user4309
133
asked Nov 12 '18 at 16:11
user4309user4309
133
asked Nov 12 '18 at 16:11
user4309user4309
133
133
2
What's aquadratic matrix of size k? Can you provide a Minimal, Complete, and Verifiable example?
– jpp
Nov 12 '18 at 16:12
Use list comprehension only if you're interested in creating a list.
– Austin
Nov 12 '18 at 16:13
add a comment |
2
What's aquadratic matrix of size k? Can you provide a Minimal, Complete, and Verifiable example?
– jpp
Nov 12 '18 at 16:12
Use list comprehension only if you're interested in creating a list.
– Austin
Nov 12 '18 at 16:13
2
2
What's a
quadratic matrix of size k? Can you provide a Minimal, Complete, and Verifiable example?– jpp
Nov 12 '18 at 16:12
What's a
quadratic matrix of size k? Can you provide a Minimal, Complete, and Verifiable example?– jpp
Nov 12 '18 at 16:12
Use list comprehension only if you're interested in creating a list.
– Austin
Nov 12 '18 at 16:13
Use list comprehension only if you're interested in creating a list.
– Austin
Nov 12 '18 at 16:13
add a comment |
2 Answers
2
active
oldest
votes
2
Looks like you want any():
if any(B[x,1] == 1 for x in range(k)):
answered Nov 12 '18 at 16:13
arshajiiarshajii
101k18180250
Does the for-loop stop as soon as the condition is fulfilled for the first x?
– user4309
Nov 12 '18 at 16:21
@user4309 Yesany()will do exactly that.
– arshajii
Nov 12 '18 at 16:21
add a comment |
1
arshajii's answer is probably right, but if you also want to have the value of the first x fulfilling your condition you could do:
try:
x = next(x for x in range(k) if B[x, 1] == 1)
# Do something with x
except StopIteration:
# Do something else
EDIT: Better yet, thanks @arshajii:
x = next(x for x in range(k) if B[x, 1] == 1, None)
if x is not None:
# Do something with x
else:
# Do something else
answered Nov 12 '18 at 16:24
jdehesajdehesa
23k43152
You can also usex = next((x for x in range(k) if B[x, 1] == 1), None)then check ifxisNoneinstead of catching an exception.
– arshajii
Nov 12 '18 at 16:35
@arshajii I always forget about that one and it's so much better, thanks!
– jdehesa
Nov 12 '18 at 16:37
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
2
Looks like you want any():
if any(B[x,1] == 1 for x in range(k)):
answered Nov 12 '18 at 16:13
arshajiiarshajii
101k18180250
Does the for-loop stop as soon as the condition is fulfilled for the first x?
– user4309
Nov 12 '18 at 16:21
@user4309 Yesany()will do exactly that.
– arshajii
Nov 12 '18 at 16:21
add a comment |
2
Looks like you want any():
if any(B[x,1] == 1 for x in range(k)):
answered Nov 12 '18 at 16:13
arshajiiarshajii
101k18180250
Does the for-loop stop as soon as the condition is fulfilled for the first x?
– user4309
Nov 12 '18 at 16:21
@user4309 Yesany()will do exactly that.
– arshajii
Nov 12 '18 at 16:21
add a comment |
2
2
2
Looks like you want any():
if any(B[x,1] == 1 for x in range(k)):
answered Nov 12 '18 at 16:13
arshajiiarshajii
101k18180250
Looks like you want any():
if any(B[x,1] == 1 for x in range(k)):
answered Nov 12 '18 at 16:13
arshajiiarshajii
101k18180250
answered Nov 12 '18 at 16:13
arshajiiarshajii
101k18180250
answered Nov 12 '18 at 16:13
arshajiiarshajii
101k18180250
answered Nov 12 '18 at 16:13
arshajiiarshajii
101k18180250
101k18180250
Does the for-loop stop as soon as the condition is fulfilled for the first x?
– user4309
Nov 12 '18 at 16:21
@user4309 Yesany()will do exactly that.
– arshajii
Nov 12 '18 at 16:21
add a comment |
Does the for-loop stop as soon as the condition is fulfilled for the first x?
– user4309
Nov 12 '18 at 16:21
@user4309 Yesany()will do exactly that.
– arshajii
Nov 12 '18 at 16:21
Does the for-loop stop as soon as the condition is fulfilled for the first x?
– user4309
Nov 12 '18 at 16:21
Does the for-loop stop as soon as the condition is fulfilled for the first x?
– user4309
Nov 12 '18 at 16:21
@user4309 Yes
any() will do exactly that.– arshajii
Nov 12 '18 at 16:21
@user4309 Yes
any() will do exactly that.– arshajii
Nov 12 '18 at 16:21
add a comment |
1
arshajii's answer is probably right, but if you also want to have the value of the first x fulfilling your condition you could do:
try:
x = next(x for x in range(k) if B[x, 1] == 1)
# Do something with x
except StopIteration:
# Do something else
EDIT: Better yet, thanks @arshajii:
x = next(x for x in range(k) if B[x, 1] == 1, None)
if x is not None:
# Do something with x
else:
# Do something else
answered Nov 12 '18 at 16:24
jdehesajdehesa
23k43152
You can also usex = next((x for x in range(k) if B[x, 1] == 1), None)then check ifxisNoneinstead of catching an exception.
– arshajii
Nov 12 '18 at 16:35
@arshajii I always forget about that one and it's so much better, thanks!
– jdehesa
Nov 12 '18 at 16:37
add a comment |
1
arshajii's answer is probably right, but if you also want to have the value of the first x fulfilling your condition you could do:
try:
x = next(x for x in range(k) if B[x, 1] == 1)
# Do something with x
except StopIteration:
# Do something else
EDIT: Better yet, thanks @arshajii:
x = next(x for x in range(k) if B[x, 1] == 1, None)
if x is not None:
# Do something with x
else:
# Do something else
answered Nov 12 '18 at 16:24
jdehesajdehesa
23k43152
You can also usex = next((x for x in range(k) if B[x, 1] == 1), None)then check ifxisNoneinstead of catching an exception.
– arshajii
Nov 12 '18 at 16:35
@arshajii I always forget about that one and it's so much better, thanks!
– jdehesa
Nov 12 '18 at 16:37
add a comment |
1
1
1
arshajii's answer is probably right, but if you also want to have the value of the first x fulfilling your condition you could do:
try:
x = next(x for x in range(k) if B[x, 1] == 1)
# Do something with x
except StopIteration:
# Do something else
EDIT: Better yet, thanks @arshajii:
x = next(x for x in range(k) if B[x, 1] == 1, None)
if x is not None:
# Do something with x
else:
# Do something else
answered Nov 12 '18 at 16:24
jdehesajdehesa
23k43152
arshajii's answer is probably right, but if you also want to have the value of the first x fulfilling your condition you could do:
try:
x = next(x for x in range(k) if B[x, 1] == 1)
# Do something with x
except StopIteration:
# Do something else
EDIT: Better yet, thanks @arshajii:
x = next(x for x in range(k) if B[x, 1] == 1, None)
if x is not None:
# Do something with x
else:
# Do something else
answered Nov 12 '18 at 16:24
jdehesajdehesa
23k43152
edited Nov 12 '18 at 16:36
answered Nov 12 '18 at 16:24
jdehesajdehesa
23k43152
answered Nov 12 '18 at 16:24
jdehesajdehesa
23k43152
answered Nov 12 '18 at 16:24
jdehesajdehesa
23k43152
23k43152
You can also usex = next((x for x in range(k) if B[x, 1] == 1), None)then check ifxisNoneinstead of catching an exception.
– arshajii
Nov 12 '18 at 16:35
@arshajii I always forget about that one and it's so much better, thanks!
– jdehesa
Nov 12 '18 at 16:37
add a comment |
You can also usex = next((x for x in range(k) if B[x, 1] == 1), None)then check ifxisNoneinstead of catching an exception.
– arshajii
Nov 12 '18 at 16:35
@arshajii I always forget about that one and it's so much better, thanks!
– jdehesa
Nov 12 '18 at 16:37
You can also use
x = next((x for x in range(k) if B[x, 1] == 1), None) then check if x is None instead of catching an exception.– arshajii
Nov 12 '18 at 16:35
You can also use
x = next((x for x in range(k) if B[x, 1] == 1), None) then check if x is None instead of catching an exception.– arshajii
Nov 12 '18 at 16:35
@arshajii I always forget about that one and it's so much better, thanks!
– jdehesa
Nov 12 '18 at 16:37
@arshajii I always forget about that one and it's so much better, thanks!
– jdehesa
Nov 12 '18 at 16:37
add a comment |
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2
What's a
quadratic matrix of size k? Can you provide a Minimal, Complete, and Verifiable example?– jpp
Nov 12 '18 at 16:12
Use list comprehension only if you're interested in creating a list.
– Austin
Nov 12 '18 at 16:13