Title:

ValueError: cannot reshape array of size X into shape $($Y$,$ Z$,...)$ in convolution layer output in Python

Description:

I$\text{'}$m implementing a forward pass for a convolutional layer in Python. The convolution appears to run, but when reshaping the output for visualization in the test script, I get the error:

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ValueError: cannot reshape array of size $30$ into shape $(3,5,5)$

This occurs when the test script attempts to reshape the convolution output data into the expected format in the display$\_$results$()$ function.

I cannot modify the test script $($including the display$\_$results$()$ function$),$ which expects the convolution output to be of a certain shape. Specifically, the output needs to be reshaped to $($output$[\text{'}$channel$\text{'}],$ output$[\text{'}$height$\text{'}],$ output$[\text{'}$width$\text{'}]).$ However, the number of elements in the array doesn't match the expected size.

Convolution Layer Function:

Here$$s the relevant part of my conv$\_$layer$\_$forward$()$ function:

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def conv$\_$layer$\_$forward$($input$\_$data, layer, param$)$:

h$\_$in $=$ input$\_$data$[\text{'}$height$\text{'}]$

w$\_$in $=$ input$\_$data$[\text{'}$width$\text{'}]$

c $=$ input$\_$data$[\text{'}$channel$\text{'}]$

batch$\_$size $=$ input$\_$data$[\text{'}$batch$\_$size'$]$

k $=$ layer$[\text{'}$k$\text{'}]$ # kernel size

pad $=$ layer$[\text{'}$pad$\text{'}]$ # padding

stride $=$ layer$[\text{'}$stride$\text{'}]$ # stride

num $=$ layer$[\text{'}$num$\text{'}]$ # number of filters $($output channels$)$

h$\_$out $=($h$\_$in $+2*$ pad $-$ k$)//$ stride $+1$

w$\_$out $=($w$\_$in $+2*$ pad $-$ k$)//$ stride $+1$

output $=\{$

'height': h$\_$out,

'width': w$\_$out,

'channel': num,

'batch$\_$size': batch$\_$size,

'data': np$.$zeros$(($batch$\_$size, h$\_$out, w$\_$out, num$))$

$\}$

try:

# Perform convolution using im$2$col $($details omitted$)$

input$\_$cols $=$ im$2$col$\_$conv$\_$batch$($input$\_$data$[\text{'}$data$\text{'}],$ k$,$ pad, stride$)$

W$\_$cols $=$ param$[\text{'}$w$\text{'}].$reshape$($num$,-1)$

conv$\_$result $=$ np$.$dot$($W$\_$cols, input$\_$cols$)$

conv$\_$result $+=$ param$[\text{'}$b$\text{'}].$reshape$(-1,1)$

conv$\_$result $=$ conv$\_$result.reshape$($num$,$ h$\_$out, w$\_$out, batch$\_$size$)$

output$[\text{'}$data$\text{'}]=$ np$.$transpose$($conv$\_$result, $(3,1,2,0))$ # Shape: $($batch$\_$size, h$\_$out, w$\_$out, num$)$

except Exception as e:

print$($f$"$Error during convolution: $\{$str$($e$)\}")$

return output

Test Script $($I CANNOT MODIFY$)$:

The test script runs several tests and calls the conv$\_$layer$\_$forward$()$ function, then tries to visualize the output. Here's the part where the error occurs:

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img$1=$ output$[\text{'}$data$\text{'}][$:$,$batch$].$reshape$($output$[\text{'}$channel$\text{'}],$ output$[\text{'}$height$\text{'}],$ output$[\text{'}$width$\text{'}])$

Expected Behavior:

The output data should be of shape $($batch$\_$size, h$\_$out, w$\_$out, num$)$ and reshaped into $($num$,$ h$\_$out, w$\_$out$)$ for each batch during visualization.

Problem:

The error indicates that the size of the array doesn't match the expected shape when reshaped. The number of elements in output$[\text{'}$data$\text{'}][$:$,$batch$]$ does not match the required shape $($output$[\text{'}$channel$\text{'}],$ output$[\text{'}$height$\text{'}],$ output$[\text{'}$width$\text{'}]).$ Specifically, it seems like the convolution output is smaller than expected.

Question:

How can I fix my conv$\_$layer$\_$forward$()$ function to ensure that the output data matches the expected shape and size required by the test script? Is there something wrong with how I calculate or reshape the convolution result?

Notes:

I cannot modify the test script or display$\_$results$().$

The padding, stride, and kernel size seem to be correct based on the provided input dimensions.

The output dimensions are calculated using the standard convolution formula.

Thanks in advance!