concatenate lists with subscripts, python

Question

to update: use the @azro code and modify only the indexes of the for. it doesn't mark me error with your answers, the code works fine, however I still don't get the expected result, I put my full code.

arch is dataframe
channels=['ch1','ch1']
targets=['op1','op2']
l=[]
m = []
n = []
for ch in channels:
    for tar in targets:
        for j in range(1,22):                                                        
            df=arch[(arch.Año.isin(año)) & (arch['Channel'] == ch) & (rcha['Week'] == j)]

           l.append(df[['time',tar]].set_index('time').rename(columns={'time' : 'time' + str(j)}))
        m.append(l)
     n.append(m)

a = []
for i in range(len(n)):
    for j in range(len(m)):
        for k in range(len(l)):
            a.append(n[i][j][k])
a = pd.concat(a, axis=1).reset_index()

by printing "a" I get

time | op1 | op1 |...| op2 | op2 |..| op1 | op1 | op2 |..| op2 
1    | 0.2 | 0.1 |   | 0.2 | 0.1 |..| 0.1 | 0.1 | 0.2 |..| 0.8
2    | 0.3 | 0.4 |   | 0.1 | 0.3 |..| 0.2 | 0.7 | 0.9 |..| 0.3
3    | 0.7 | 0.8 |   | 0.9 | 0.11|..| 0.4 | 0.8 | 0.7 |..| 0.8

I have it like this, because I have two elements in "channels" and two elements in "targets" and I need to print a table for "ch1 with op1", "ch1 with op2", "ch2 with op1", "ch2 with op2".

for ch1
time | op1 | op1 |..
1    | 0.2 | 0.1 |..  
2    | 0.3 | 0.4 |..
3    | 0.7 | 0.8 |

time | op2 | op2 |..
1    | 0.2 | 0.1 |..
2    | 0.1 | 0.3 |..
3    | 0.9 | 0.11|.. 


for ch2

time | op1 | op1 | ..
1    | 0.1 | 0.1 | ..
2    | 0.2 | 0.7 | ..
3    | 0.4 | 0.8 | ..

time | op2 |..| op2 
1    | 0.2 |..| 0.8
2    | 0.9 |..| 0.3
3    | 0.7 |..| 0.8

As the error states, pd.concat expects to concatenate multiple things, but you passed it a single DataFrame. Perhaps a = pd.concat(np.flatten(n), axis=1).reset_index()? — 0x5453
– 0x5453, Commented Jul 29, 2020 at 21:00

TheManWithNoPlan · Accepted Answer · 2020-07-29 21:00:06Z

0

I think you are trying to do something like this:

a=n[0][0][0]
for i in range(len(n)):
    for j in range(len(n)):
        for k in range(len(n)):
            if not i==j==k==0:
                a=pd.concat((a, n[i][j][k]),axis=1).reset_index()

'a' is your cumulative concatenation, so you then need to concatenate that with the next entry

answered Jul 29, 2020 at 21:00

TheManWithNoPlan

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1 Comment

KLM Over a year ago

thanks, your answer solves the error, but I still don't get the desired result, I have already updated my code to see if it is clearer

azro · Accepted Answer · 2020-07-29 21:00:20Z

0

You need to pass multiple Dataframe to concat not just one, you'd better to it in one-shot

a = []
for i in range(len(n)):
    for j in range(len(n)):
        for k in range(len(n)):
            a.append(n[i][j][k])
a = pd.concat(a, axis=1).reset_index()

answered Jul 29, 2020 at 21:00

azro

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1 Comment

KLM Over a year ago

thanks, your answer solves the error, but I still don't get the desired result only the first two values concatenate me, not all , I have already updated my code to see if it is clearer

Ehsan · Accepted Answer · 2020-07-29 21:28:44Z

0

If I understand it correctly, you want this:

import numpy as np
a = pd.concat(np.flatten(np.array(n)), axis=1).reset_index()

If this does not work, please share with us a small sample of your n array to make it work.

answered Jul 29, 2020 at 21:28

Ehsan

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2 Comments

KLM Over a year ago

thanks, your answer solves the error, but I still don't get the desired result, I have already updated my code to see if it is clearer

Ehsan Over a year ago

@KLM Please provide a sample input n and desired output a so we understand better. The code you updated (which I assume does not achieve what you desire) does not make it clearer. Thank you. And what is channels and arch in your updated code? Please make it reproducible

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