Writting columns of data in *.dat file in Python

Question

I want to write specific data, say, after analysis I get in the following fashion shown in the above figure so that whenever requires I can extract any particular column as I wish following the commands:

f= np.loadtxt("Data1.dat", unpack=True)
x = f[0,:]

However, I have tried pd.DataFrame() but didn't work.

import csv 
import numpy as np
import pandas as pd
 
x = [0.11, 2.15, 0.39, 5.79, 6.53]
y = [99.2, -0.32, -12.95, -2.5, -7.5]

n = len(x)
 
#with open('data1.dat', 'w', newline='') as f:  
#   wtr = csv.writer(f)
#   for k in range(n):
#       wtr.writerow([x[k], y[k]])
  
df = pd.DataFrame({"x": x, "y": y})
df.to_csv('data1.dat')

Answer 1

You can use column_stack from numpy:

import numpy as np

x = [0.11, 2.15, 0.39, 5.79, 6.53]
y = [99.2, -0.32, -12.95, -2.5, -7.5]

df = np.column_stack((x,y))

np.savetxt('data1.dat', df, header = ' x, y ')

Later, your data should look like you want. Then it's easy to read with:

data = np.loadtxt('data1.dat', unpack=True)
x = data[0]
y = data[1]

Good luck!

Answer 2

$project can be used to get required values.

Example:

bson.M {
    "$project": bson.M {
        "A": "$_id.A",
        "B": "$_id.B",
        "Total": 1
    }
}