How to Append array from list of array?

Question

I am running the following script, but it is not giving me the desired output. It's printing the last element only; i want to print each element.

a = ([0.1, 0.2, 0.43, 0.44,0.55,0.36,0.57,0.58,0.39,0.40])
for k in range(len(a)):
   # print(a[i])
   #print (a[k])
    import numpy as np

array = np.array([[i, j,a[k]] 
                  for i in range(1, 5)
                  for j in range(i + 1, 6)])
array

Expected output

array([[ 1,  2, 0.1],
       [ 1,  3, 0.2],
       [ 1,  4, 0.43],
       [ 1,  5, 0.44],
       [ 2,  3, 0.55],
       [ 2,  4, 0.36],
       [ 2,  5, 0.57],
       [ 3,  4, 0.58],
       [ 3,  5, 0.39],
       [ 4,  5, 0.40]])

when you define you array, it's outside the for loop you wrote so k doesn't change, hence the last value is always a[k] where k is 9 — Emi OB
– Emi OB, Commented Jan 5, 2023 at 11:28

Talha Tayyab · Accepted Answer · 2023-01-05 12:40:24Z

2

a=[0.1, 0.2, 0.43, 0.44,0.55,0.36,0.57,0.58,0.39,0.40]
k=[[i, j] for i in range(1, 5) for j in range(i + 1, 6)]

print(k)
# [[1, 2], [1, 3], [1, 4], [1, 5], [2, 3], [2, 4], [2, 5], [3, 4], [3, 5], [4, 5]]

for x,y in enumerate(a):
    k[x].append(y)
print(k)

# [[1, 2, 0.1], [1, 3, 0.2], [1, 4, 0.43], [1, 5, 0.44], [2, 3, 0.55], [2, 4, 0.36], [2, 5, 0.57], [3, 4, 0.58], [3, 5, 0.39], [4, 5, 0.4]]

k=np.array(k) #convert to np array
print(k)

array([[1.  , 2.  , 0.1 ],
       [1.  , 3.  , 0.2 ],
       [1.  , 4.  , 0.43],
       [1.  , 5.  , 0.44],
       [2.  , 3.  , 0.55],
       [2.  , 4.  , 0.36],
       [2.  , 5.  , 0.57],
       [3.  , 4.  , 0.58],
       [3.  , 5.  , 0.39],
       [4.  , 5.  , 0.4 ]])

answered Jan 5, 2023 at 12:40

Talha Tayyab

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