Compute the cumulative sum of the tensor x
along axis
.
meridian
.
backend
.
cumsum
(
x
,
axis
=
0
,
exclusive
=
False
,
reverse
=
False
,
name
=
None
)
By default, this op performs an inclusive cumsum, which means that the first element of the input is identical to the first element of the output: For example:
>>>
# tf.cumsum([a, b, c]) # [a, a + b, a + b + c]
>>>
x
=
tf
.
constant
([
2
,
4
,
6
,
8
])
>>>
tf
.
cumsum
(
x
)
< tf
.
Tensor
:
shape
=
(
4
,),
dtype
=
int32
,
numpy
=
array
([
2
,
6
,
12
,
20
],
dtype
=
int32
)
>
>>>
# using varying `axis` values
>>>
y
=
tf
.
constant
(
[[
2
,
4
,
6
,
8
]
,
[
1
,
3
,
5
,
7
]]
)
>>>
tf
.
cumsum
(
y
,
axis
=
0
)
< tf
.
Tensor
:
shape
=
(
2
,
4
),
dtype
=
int32
,
numpy
=
array
(
[[
2
,
4
,
6
,
8
]
,
[
3
,
7
,
11
,
15
]]
,
dtype
=
int32
)
>
>>>
tf
.
cumsum
(
y
,
axis
=
1
)
< tf
.
Tensor
:
shape
=
(
2
,
4
),
dtype
=
int32
,
numpy
=
array
(
[[
2
,
6
,
12
,
20
]
,
[
1
,
4
,
9
,
16
]]
,
dtype
=
int32
)
>
By setting the exclusive
kwarg to True
, an exclusive cumsum is performed
instead:
>>>
# tf.cumsum([a, b, c], exclusive=True) => [0, a, a + b]
>>>
x
=
tf
.
constant
([
2
,
4
,
6
,
8
])
>>>
tf
.
cumsum
(
x
,
exclusive
=
True
)
< tf
.
Tensor
:
shape
=
(
4
,),
dtype
=
int32
,
numpy
=
array
([
0
,
2
,
6
,
12
],
dtype
=
int32
)
>
By setting the reverse
kwarg to True
, the cumsum is performed in the
opposite direction:
>>>
# tf.cumsum([a, b, c], reverse=True) # [a + b + c, b + c, c]
>>>
x
=
tf
.
constant
([
2
,
4
,
6
,
8
])
>>>
tf
.
cumsum
(
x
,
reverse
=
True
)
< tf
.
Tensor
:
shape
=
(
4
,),
dtype
=
int32
,
numpy
=
array
([
20
,
18
,
14
,
8
],
dtype
=
int32
)
>
This is more efficient than using separate tf.reverse
ops.
The reverse
and exclusive
kwargs can also be combined:
>>>
# tf.cumsum([a, b, c], exclusive=True, reverse=True) # [b + c, c, 0]
>>>
x
=
tf
.
constant
([
2
,
4
,
6
,
8
])
>>>
tf
.
cumsum
(
x
,
exclusive
=
True
,
reverse
=
True
)
< tf
.
Tensor
:
shape
=
(
4
,),
dtype
=
int32
,
numpy
=
array
([
18
,
14
,
8
,
0
],
dtype
=
int32
)
>
Args
A
Tensor
. Must be one of the following types: float32
, float64
, int64
, int32
, uint8
, uint16
, int16
, int8
, complex64
, complex128
, qint8
, quint8
, qint32
, half
.
Returns
A
Tensor
. Has the same type as x
.