Concatenate many 1xn arrays using Python

Question

I have one 1xn array like this:

data = [-2 -1 -3 -5 2 5 8 9 ..... 8]

Now, I want concatenate this with other similar 1xn arrays:

data2 = [0 3 0 0 ..... 5]

final is a big matrix with many rows

[data]
[data2]
...
[data1000]

What is the Python code for this?

data as displayed looks like a (n,) 1d shaped array (no commas, so it's not a list). You want to make a (m,n) array, with mm rows? — hpaulj
– hpaulj, Commented May 16, 2017 at 3:17
exactly finally is a matrix mxn, @NaN np.concatenate() no work, — Oscar David
– Oscar David, Commented May 16, 2017 at 3:22
Try np.array on a list of the 1d arrays: np.array([data, data2, data3, ... ,data1000]) — hpaulj
– hpaulj, Commented May 16, 2017 at 3:27
How is np.concatenate failing? Is it returning an error, or an undesired result? — EFT
– EFT, Commented May 16, 2017 at 14:16

Good Morning Captain · Accepted Answer · 2017-05-16 03:09:17Z

2

totalData = [data, data2, data3, ... , data1000]

Would be the easiest way to do this if you have no way to iterate over the data.

answered May 16, 2017 at 3:09

Good Morning Captain

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2 Comments

Oscar David Over a year ago

but i need mxn matrix

Good Morning Captain Over a year ago

The list of lists will act like a a matrix when you want to retrieve or change data points. In the example above totalData[2][2]will be equal to the third data entry of data3

Allen Qin · Accepted Answer · 2017-05-16 04:41:09Z

0

data = [1,2,3,4]
data2 = [1,2,3]

#put the list of lists to a DataFrame which will make the equal length and fill missing elements with NA. Then use values to get the M*N numpy array.
pd.DataFrame([data,data2]).values
Out[371]: 
array([[  1.,   2.,   3.,   4.],
       [  1.,   2.,   3.,  nan]])

answered May 16, 2017 at 4:41

Allen Qin

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Comments

titipata · Accepted Answer · 2017-05-16 05:12:29Z

0

You can also use np.vstack

import numpy as np
data = [-2, -1, -3, -5, 2, 5, 8, 9, 8]
np.vstack([data, data])
# [[-2 -1 -3 -5  2  5  8  9  8]
#  [-2 -1 -3 -5  2  5  8  9  8]]

answered May 16, 2017 at 5:12

titipata

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