# Submatrix replacement error in a matrix
**URL:** https://discourse.julialang.org/t/submatrix-replacement-error-in-a-matrix/10849
**Category:** General Usage
**Created:** [May 11, 2018, 10:40pm UTC](https://discourse.julialang.org/t/submatrix-replacement-error-in-a-matrix/10849 "2018-05-11T22:40:50Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@paulobuchsbaum](https://discourse.julialang.org/u/paulobuchsbaum)
#### Post date: [May 11, 2018, 10:40pm UTC](https://discourse.julialang.org/t/submatrix-replacement-error-in-a-matrix/10849/1 "2018-05-11T22:40:50Z")
In this below code there is a weird error message:
```julia
joja = [1 2 3; 4 5 6; 7 8 9]
joja[2:3,2:3] = [1 2; 3 4] # ok
joja2 = reshape(1:9,3,3)
joja2[2:3,2:3] = [1 2; 3 4] # error (reshaped array)
joja3 = copy(joja2)
joja3[2:3,2:3] = [1 2; 3 4] # ok
```
I know that `reshaped array` is a different animal, but why it happens?
---
### Author:  [@dpsanders](https://discourse.julialang.org/u/dpsanders)
#### Post date: [May 11, 2018, 10:54pm UTC](https://discourse.julialang.org/t/submatrix-replacement-error-in-a-matrix/10849/2 "2018-05-11T22:54:04Z")
Please report the exact error by copying and pasting an actual Julia session.
---
### Author:  [@paulobuchsbaum](https://discourse.julialang.org/u/paulobuchsbaum)
#### Post date: [May 12, 2018, 12:57am UTC](https://discourse.julialang.org/t/submatrix-replacement-error-in-a-matrix/10849/3 "2018-05-12T00:57:19Z")
Thanks for your feedback
The two lines that generates an error (in the middle) was
```julia
Julia >joja2 = reshape(1:9,3,3)
3×3 Base.ReshapedArray{Int64,2,UnitRange{Int64},Tuple{}}:
1 4 7
2 5 8
3 6 9
Julia>joja2[2:3,2:3] = [1 2; 3 4]
ERROR: indexed assignment fails for a reshaped range; consider calling collect
Stacktrace:
[1] macro expansion at .\multidimensional.jl:558 [inlined]
[2] macro expansion at .\cartesian.jl:64 [inlined]
[3] macro expansion at .\multidimensional.jl:556 [inlined]
[4] _unsafe_setindex!(::IndexLinear, ::Base.ReshapedArray{Int64,2,UnitRange{Int
64},Tuple{}}, ::Array{Int64,2}, ::UnitRange{Int64}, ::UnitRange{Int64}) at .\mul
tidimensional.jl:549
[5] macro expansion at .\multidimensional.jl:541 [inlined]
[6] _setindex! at .\multidimensional.jl:537 [inlined]
[7] setindex!(::Base.ReshapedArray{Int64,2,UnitRange{Int64},Tuple{}}, ::Array{I
nt64,2}, ::UnitRange{Int64}, ::UnitRange{Int64}) at .\abstractarray.jl:968
```
A simular approach it’s ok, but uses `pure array` instead `reshaped array`
```julia
Julia>joja = [1 2 3; 4 5 6; 7 8 9]
3×3 Array{Int64,2}:
1 2 3
4 5 6
7 8 9
Julia>joja[2:3,2:3] = [1 2; 3 4]
2×2 Array{Int64,2}:
1 2
3 4
```
---
### Author:  [@tomaklutfu](https://discourse.julialang.org/u/tomaklutfu)
#### Post date: [May 12, 2018, 3:08am UTC](https://discourse.julialang.org/t/submatrix-replacement-error-in-a-matrix/10849/4 "2018-05-12T03:08:18Z")
There is no setindex! for ranges. The error suggests you to collect it as a regular array first then assign values.
---
### Author:  [@paulobuchsbaum](https://discourse.julialang.org/u/paulobuchsbaum)
#### Post date: [May 12, 2018, 3:25am UTC](https://discourse.julialang.org/t/submatrix-replacement-error-in-a-matrix/10849/5 "2018-05-12T03:25:56Z")
@tomaklutfu, in that case is not a range, is a real array, because `reshape` function get a range and convert it to an array in any shape.
However, it’s a little bit different from a declared array in the second piece of code. It’s a reshaped array (`ReshapedArray` in the error message) so it generates an error, but it lacks logic!
Notice that there is no 3D ranges, but `reshape` function produces 3D arrays:
```julia
vet = reshape(1:24,2,3,4)
println(vet[1,2,3]) # shows 15.
```
---
### Author:  [@Stephen\_Vavasis](https://discourse.julialang.org/u/Stephen_Vavasis)
#### Post date: [May 12, 2018, 3:47am UTC](https://discourse.julialang.org/t/submatrix-replacement-error-in-a-matrix/10849/6 "2018-05-12T03:47:34Z")
A reshaped range is not the same as a reshaped `Array`. Ranges (even reshaped ones) are read-only. This is intentional language behavior. As the previous response suggests, you can first convert the range to a `Vector` via a call to the`Vector` constructor or to `collect`.
---
### Author:  [@paulobuchsbaum](https://discourse.julialang.org/u/paulobuchsbaum)
#### Post date: [May 12, 2018, 4:05am UTC](https://discourse.julialang.org/t/submatrix-replacement-error-in-a-matrix/10849/7 "2018-05-12T04:05:23Z")
@Stephen_Vavasis, you are right! This reshaped range is read-only. I’ve got it. `copy()` or `collect()` do the job. Thanks for your explanation.
It’s pretty amazing so much power in a programming language.
The below code works!
```julia
Vals = [30 60; 45 30]
Dest = collect(reshape(1.:9.,3,3))
Dest[2:3,2:3] = sind.(Vals) .* cosd.(Vals)
```
Before submatrix assignment:
> **Julia\>** Dest
> 3×3 Array{Float64,2}:
> 1.0 4.0 7.0
> 2.0 5.0 8.0
> 3.0 6.0 9.0
After:
> **Julia\>** Dest
> 3×3 Array{Float64,2}:
> 1.0 4.0 7.0
> 2.0 0.433013 0.433013
> 3.0 0.5 0.433013