Add column to numpy matrix

[Gigux]

Dear all,
I am trying to add a column to a numpy matrix. I can make a running example as follows:

import numpy as np
X = np.random.uniform(size=(10,3))
X.shape
Out[3]: (10, 3)
n,m = X.shape
X0 = np.ones((n,1))
X0.shape
Out[6]: (10, 1)
Xnew = np.hstack((X,X0))
Xnew.shape
Out[8]: (10, 4)

The data I got comes from a Pandas dataframe which I converted to numpy with .to_numpy, but then:

import pandas as pd
df =  pd.read_csv("Data.tsv", delimiter='\t')
X = df[['mr', 'fcn', 'weight']]
x = X.to_numpy()
S = df[['serial']]
sa = S.to_numpy() 
s = sa.ravel()
x.shape 
Out[14]: (15744, 3)
s.shape 
Out[15]: (15744,)
z =  np.hstack((x, s))
Traceback (most recent call last):

  File "<ipython-input-16-c88a113c6e49>", line 1, in <module>
    z =  np.hstack((x, s))

  File "/home/gigiux/.local/lib/python3.6/site-packages/numpy/core/shape_base.py", line 340, in hstack
    return _nx.concatenate(arrs, 1)

ValueError: all the input arrays must have same number of dimensions

This is also the case for stack, vstack, concatenate(axis=0,1,2). Nevertheless, all these objects are numpy arrays:

type(X)
Out[6]: numpy.ndarray
type(X0)
Out[7]: numpy.ndarray
type(Xnew)
Out[8]: numpy.ndarray
type(x)
Out[2]: numpy.ndarray
type(s)
Out[4]: numpy.ndarray

What am I missing? Why X0 has two dimensions (10, 1) but s has only one (15744)? Is that the problem?
Thank you

[scidam]

Is that the problem?

Yes. You could be able to append array with shape (15744, 1);

This should work:

np.hstack((x, s[:, np.newaxis]))