Saving array in file and then loading it in Octave? Error: struct cannot be indexed with {

Question

I get the error

 struct cannot be indexed with {' in Octave.

What I'm trying to do is to save an array in a file by doing:

save myfile.mat initialW

The array seems to be saved ok in the file. Now I want to load it, so I wrote:

numberOfHiddenLayers = length(hiddenLayers);
w = cell(numberOfHiddenLayers + 1, 1);
w = load("myfile.mat");

However this doesn't seem to work. Any help?

myFile.mat looks like this:

# Created by Octave 5.1.0, Sat May 11 23:56:06 2019 GMT <unknown@DESKTOP-4LP8KO2>
# name: initialW
# type: global cell
# rows: 3
# columns: 1
# name: <cell-element>
# type: matrix
# rows: 8
# columns: 3
 0.11396577078177994 -0.35348554375077296 -0.075606765835858347
 -0.57613421825993738 -0.54574495840109649 -0.094554469152263232
 -0.31746528997142315 -0.46945201018320487 -0.119175071441675
 -0.23112104844315234 -0.015682264154657233 0.34987783444013509
 -0.087880331273064327 -0.19609313736912465 -0.08929095997252362
 -0.080653681379305231 0.024968754990479569 0.24949668431650684
 -0.57498895224664437 0.29920144551430461 -0.50083852142549268
 -0.3961249607134249 0.25330869897866082 0.25478925191660773


# name: <cell-element>
# type: matrix
# rows: 8
# columns: 9
 0.0037531259407581619 0.43063491636241652 -0.15445269549506291 0.47739161602226637 0.22753868435063779 -0.020492674304004144 -0.057513893868040733 -0.059060562491990765 -0.25706911999311255
 -0.29424894306440108 0.38336286612135578 -0.16776741033203713 0.46943337027631832 0.13408640078121992 -0.31554901391689794 0.35099674273923137 -0.091832499829088587 0.30933982744981386
 0.52316428666987069 0.27341366734288147 0.51082650460372281 0.49809576149309504 0.37444903641719957 0.38334119916001402 0.42842076982657767 -0.24217696807363465 0.28086557806980544
 -0.073322311691991215 0.63483655613700107 0.27533329919913868 -0.048081459516434499 -0.2267065362144246 0.64395424194737783 0.58767652657219105 0.41793542891042484 0.63321069992358114
 0.65763013238306822 0.02860044065789058 -0.011829632755802955 0.22009594392084614 -0.26511909072695583 0.57370613947506088 0.11415461587493758 0.10573792459512454 -0.32427434895492757
 0.0089604833881801182 -0.073811064790883618 -0.20709124889541619 -0.036291825999526517 0.52062296154868948 -0.011081755811460203 -0.31768168116882467 0.60905440138955669 0.17623419475038399
 -0.27776341169684216 0.61262393897374579 0.065512487276322307 -0.047081972124068172 0.55430062047934725 -0.33326753953006594 0.23202447961516875 0.17662506269733375 0.34004162952881817
 -0.046484818259064919 -0.32230299619629554 0.18841716283341831 -0.18689054271483652 0.026911300930141047 0.58017623550299824 0.12685162090341895 0.29067778228781277 0.56684018254895219


# name: <cell-element>
# type: matrix
# rows: 1
# columns: 9
 0.40736020065140749 0.31486116916450352 0.085860186186408449 -0.10247723839970202 -0.14917985837470693 0.65015717261764294 -0.1038654730028068 0.38554195073868397 -0.039542106657368348

Have you looked at w? It's a struct after the load

Mad Physicist
– Mad Physicist

2019-05-12 04:29:21 +00:00
Commented May 12, 2019 at 4:29 — Mad Physicist
– Mad Physicist, Commented May 12, 2019 at 4:29

Mad Physicist · Accepted Answer · 2019-05-12 04:34:53Z

2

When you load a mat-file with a single output argument, it loads the data into a struct with fields that are the names of your variables. w is a struct with field initialW after you call load.

When you assign to a variable without any indexing expression on the left hand side, you discard the previous value. So the cell array your started with is simply overwritten by the struct.

You can do either

w = load(...);
w = w.initialW;

Or, if you want to use the cells:

w = cell(...);
iw = load(...);
w{1:length(iw.initialW)} = iw.initialW;

edited May 12, 2019 at 4:34

answered May 12, 2019 at 4:07

Mad Physicist

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2 Comments

Flama Over a year ago

initialW is the same type as w. w is an array and I want to fill each position with the data in myfile.mat

Mad Physicist Over a year ago

Just updated my answer. You should add your first comment to the question. It's much more important than the contents of the file.

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