ValueError: could not broadcast input array from shape (11253,1) into shape (11253)

Question

I am creating a Neural Network using this example and I am getting the error "ValueError: could not broadcast input array from shape (11253,1)" into shape (11253), in the line : trainPredictPlot[look_back:len(trainPredict)+look_back] = trainPredicty My code is:

import csv
import math
import numpy as np 
import pandas as pd
from keras.models import Sequential
from keras.layers import Dense
import datetime
import matplotlib.pyplot as plt
from sklearn.model_selection import train_test_split

X1 = [1:16801] #16,800 values
Y1 = [1:16801]#16,800 values

train_size = int(len(X1) * 0.67)
test_size = len(X1) - train_size

train, test = X1[0:train_size,], X1[train_size:len(X1),]
def Data(X1, look_back=1):
     dataX, dataY = [], []
     for i in range(len(X1)-look_back-1):
         a = X1[i:(i+look_back), 0]
         dataX.append(a)
         dataY.append(Y1[i + look_back, 0])
     return numpy.array(dataX), numpy.array(dataY)

look_back = 1
trainX, testX = Data(train, look_back)

testX, testY = Data(test, look_back)

look_back = 1
trainX, testX = Data(train, look_back)

testX, testY = Data(test, look_back)


trainPredict = model.predict(trainX)
testPredict = model.predict(testX)

trainPredictPlot = numpy.empty_like(Y1)
trainPredictPlot[look_back:len(trainPredict)+look_back] = trainPredict

testPredictPlot = numpy.empty_like(Y1) 
testPredictPlot[len(trainPredict)+(look_back*2)+1:len(X1)-1] = testPredict

I have 16,800 values for X1 which look like:

[0.03454225 0.02062136 0.00186715 ... 0.92857565 0.64930691 0.20325924]

And my Y1 data looks like:

[ 2.25226244  1.44078451  0.99174488 ... 12.8397099   9.75722427 7.98525797]

My traceback error message is:

ValueError                                Traceback (most recent call last)
<ipython-input-9-e4da8990335b> in <module>()
    116 trainPredictPlot = numpy.empty_like(Y1)
    117 
--> 118 trainPredictPlot[look_back:len(trainPredict)+look_back] = trainPredict
    119 
    120 testPredictPlot = numpy.empty_like(Y1)

ValueError: could not broadcast input array from shape (11253,1) into shape (11253)

Answer 1

Convert trainPredict from 2D array to 1D vector before assigning:

trainPredictPlot[look_back:len(trainPredict)+look_back] = trainPredict.ravel()