For loop not properly appending values

Question

Im trying to store 60 values to x and the next one to the y and then shift it 1 up and store 60 values to x and the next one to the y. But the for loop only works once for the x values the y values some how do get stored properly. And the size of my dataset is not the problem as storing the y values work. It's just the x values that don't store and when debugging the x sets are just empty array's except the first one. What am i doing wrong?

import math
import numpy as np
import pandas as pd

df = pd.read_csv('dataset.csv')

print(df)

dataset = df.values

data_len = math.ceil(len(dataset) * .1)

data = dataset[0:data_len , :]
print(data)

x = []
y = []

for i in range(60, len(data)):
    x.append(data[60-i:i, 0])
    y.append(data[i, 0])

I suspect the line before the last one should be: `x.append(data[i-60:i, 0])` — Grzegorz Skibinski, Nov 21 '20 at 22:27
Maybe you should show a simple example of data and expected result for "x" (but with e. g. only 10 values or so) as properly formatted text in the question. — Michael Butscher, Nov 21 '20 at 22:38
Do you mean 60 values in `x`, the 61st in `y`, 62-121 in `x`, 122nd in `y` and so on and so forth? — Nikolaos Chatzis, Nov 21 '20 at 22:45
Please provide sample data in a [reproducible way](https://stackoverflow.com/questions/20109391). Otherwise people won't be able to test. Please also show the expected output explicitly. — Bill Huang, Nov 22 '20 at 00:31

score 0 · Accepted Answer · answered Nov 22 '20 at 09:48

I think that you should try to avoid using a for loop, in numpy it is often faster to create masks and work with that. If i understand your question correctly, you want to store 0-59 in x, then 60 in y, then 61-119 in x, then 120 in y and so on.

If that is the correct understanding i would try this instead:

dataset = np.random.randint(1,1000,size=1000) #generating an example

mask = np.zeros(len(dataset),dtype=np.bool)
mask[60::60] = 1 #indices of the ys

y = dataset[mask]
x = dataset[~mask]

For loop not properly appending values

1 Answers1