execution order of expressions in a list comprehensions [duplicate]
This question already has an answer here:
Understanding nested list comprehension
2 answers
Given the following expressions:
matrix = [[1,2,3],[4,5,6],[7,8,9]]
A matrix is created, then a list comprehension is executed to create a flat list. The comprehension runs from left to right.
flat = [x for row in matrix for x in row]
Subsequently for each row in the matrix its values are squared. How is this comprehension evaluated?
squared = [[x**2 for x in row] for row in matrix]
python list list-comprehension
edited Nov 21 '18 at 19:55
timgeb
51.3k126794
asked Nov 21 '18 at 19:49
dcrearerdcrearer
69421027
marked as duplicate by roganjosh, juanpa.arrivillaga python
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Nov 21 '18 at 20:01
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
add a comment |
This question already has an answer here:
Understanding nested list comprehension
2 answers
Given the following expressions:
matrix = [[1,2,3],[4,5,6],[7,8,9]]
A matrix is created, then a list comprehension is executed to create a flat list. The comprehension runs from left to right.
flat = [x for row in matrix for x in row]
Subsequently for each row in the matrix its values are squared. How is this comprehension evaluated?
squared = [[x**2 for x in row] for row in matrix]
python list list-comprehension
edited Nov 21 '18 at 19:55
timgeb
51.3k126794
asked Nov 21 '18 at 19:49
dcrearerdcrearer
69421027
marked as duplicate by roganjosh, juanpa.arrivillaga python
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Nov 21 '18 at 20:01
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
let me review that post... thanks for the reference
– dcrearer
Nov 21 '18 at 19:54
add a comment |
This question already has an answer here:
Understanding nested list comprehension
2 answers
Given the following expressions:
matrix = [[1,2,3],[4,5,6],[7,8,9]]
A matrix is created, then a list comprehension is executed to create a flat list. The comprehension runs from left to right.
flat = [x for row in matrix for x in row]
Subsequently for each row in the matrix its values are squared. How is this comprehension evaluated?
squared = [[x**2 for x in row] for row in matrix]
python list list-comprehension
edited Nov 21 '18 at 19:55
timgeb
51.3k126794
asked Nov 21 '18 at 19:49
dcrearerdcrearer
69421027
This question already has an answer here:
Understanding nested list comprehension
2 answers
Given the following expressions:
matrix = [[1,2,3],[4,5,6],[7,8,9]]
A matrix is created, then a list comprehension is executed to create a flat list. The comprehension runs from left to right.
flat = [x for row in matrix for x in row]
Subsequently for each row in the matrix its values are squared. How is this comprehension evaluated?
squared = [[x**2 for x in row] for row in matrix]
This question already has an answer here:
Understanding nested list comprehension
2 answers
python list list-comprehension
python list list-comprehension
edited Nov 21 '18 at 19:55
timgeb
51.3k126794
asked Nov 21 '18 at 19:49
dcrearerdcrearer
69421027
edited Nov 21 '18 at 19:55
timgeb
51.3k126794
asked Nov 21 '18 at 19:49
dcrearerdcrearer
69421027
edited Nov 21 '18 at 19:55
timgeb
51.3k126794
edited Nov 21 '18 at 19:55
timgeb
51.3k126794
edited Nov 21 '18 at 19:55
timgeb
51.3k126794
51.3k126794
asked Nov 21 '18 at 19:49
dcrearerdcrearer
69421027
asked Nov 21 '18 at 19:49
dcrearerdcrearer
69421027
asked Nov 21 '18 at 19:49
dcrearerdcrearer
69421027
69421027
marked as duplicate by roganjosh, juanpa.arrivillaga python
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Nov 21 '18 at 20:01
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
marked as duplicate by roganjosh, juanpa.arrivillaga python
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Nov 21 '18 at 20:01
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
let me review that post... thanks for the reference
– dcrearer
Nov 21 '18 at 19:54
add a comment |
let me review that post... thanks for the reference
– dcrearer
Nov 21 '18 at 19:54
let me review that post... thanks for the reference
– dcrearer
Nov 21 '18 at 19:54
let me review that post... thanks for the reference
– dcrearer
Nov 21 '18 at 19:54
add a comment |
1 Answer
1
active
oldest
votes
The first comprehension is equivalent to:
flat =
for row in matrix:
for x in row:
flat.append(x)
The second comprehension is equivalent to:
squared =
for row in matrix:
tmp =
for x in row:
tmp.append(x**2)
squared.append(tmp)
(Except for creating additional variables in the enclosing scope like x, row, tmp.)
answered Nov 21 '18 at 19:53
timgebtimgeb
51.3k126794
1
thanks for the clear concise sample...
– dcrearer
Nov 21 '18 at 19:57
@wim right, I overlooked those. Thedel-ing is probably unnecessary to get the point across.
– timgeb
Nov 21 '18 at 20:17
add a comment |
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
The first comprehension is equivalent to:
flat =
for row in matrix:
for x in row:
flat.append(x)
The second comprehension is equivalent to:
squared =
for row in matrix:
tmp =
for x in row:
tmp.append(x**2)
squared.append(tmp)
(Except for creating additional variables in the enclosing scope like x, row, tmp.)
answered Nov 21 '18 at 19:53
timgebtimgeb
51.3k126794
1
thanks for the clear concise sample...
– dcrearer
Nov 21 '18 at 19:57
@wim right, I overlooked those. Thedel-ing is probably unnecessary to get the point across.
– timgeb
Nov 21 '18 at 20:17
add a comment |
The first comprehension is equivalent to:
flat =
for row in matrix:
for x in row:
flat.append(x)
The second comprehension is equivalent to:
squared =
for row in matrix:
tmp =
for x in row:
tmp.append(x**2)
squared.append(tmp)
(Except for creating additional variables in the enclosing scope like x, row, tmp.)
answered Nov 21 '18 at 19:53
timgebtimgeb
51.3k126794
1
thanks for the clear concise sample...
– dcrearer
Nov 21 '18 at 19:57
@wim right, I overlooked those. Thedel-ing is probably unnecessary to get the point across.
– timgeb
Nov 21 '18 at 20:17
add a comment |
The first comprehension is equivalent to:
flat =
for row in matrix:
for x in row:
flat.append(x)
The second comprehension is equivalent to:
squared =
for row in matrix:
tmp =
for x in row:
tmp.append(x**2)
squared.append(tmp)
(Except for creating additional variables in the enclosing scope like x, row, tmp.)
answered Nov 21 '18 at 19:53
timgebtimgeb
51.3k126794
The first comprehension is equivalent to:
flat =
for row in matrix:
for x in row:
flat.append(x)
The second comprehension is equivalent to:
squared =
for row in matrix:
tmp =
for x in row:
tmp.append(x**2)
squared.append(tmp)
(Except for creating additional variables in the enclosing scope like x, row, tmp.)
answered Nov 21 '18 at 19:53
timgebtimgeb
51.3k126794
edited Nov 21 '18 at 20:17
answered Nov 21 '18 at 19:53
timgebtimgeb
51.3k126794
answered Nov 21 '18 at 19:53
timgebtimgeb
51.3k126794
answered Nov 21 '18 at 19:53
timgebtimgeb
51.3k126794
51.3k126794
1
thanks for the clear concise sample...
– dcrearer
Nov 21 '18 at 19:57
@wim right, I overlooked those. Thedel-ing is probably unnecessary to get the point across.
– timgeb
Nov 21 '18 at 20:17
add a comment |
1
thanks for the clear concise sample...
– dcrearer
Nov 21 '18 at 19:57
@wim right, I overlooked those. Thedel-ing is probably unnecessary to get the point across.
– timgeb
Nov 21 '18 at 20:17
1
1
thanks for the clear concise sample...
– dcrearer
Nov 21 '18 at 19:57
thanks for the clear concise sample...
– dcrearer
Nov 21 '18 at 19:57
@wim right, I overlooked those. The
del-ing is probably unnecessary to get the point across.– timgeb
Nov 21 '18 at 20:17
@wim right, I overlooked those. The
del-ing is probably unnecessary to get the point across.– timgeb
Nov 21 '18 at 20:17
add a comment |
let me review that post... thanks for the reference
– dcrearer
Nov 21 '18 at 19:54