Replace values of a numpy array by values from another numpy array

Question

i have a 1000 * 1000 numpy array with 1 million values which was created as follows :

>>import numpy as np
>>data = np.loadtxt(\'space_data.txt\         


        

Answer 1

# Create a dataframe out of your 'data' array and make a dictionary out of your 'key' array. 
import numpy as np
import pandas as pd

data = np.array([[ 13.,  15.,  15.],
               [ 14.,  13.,  14. ],
               [ 16.,  13.,  13. ]])
data_df = pd.DataFrame(data)
key  = dict({10 : 'S',11 : 'S', 12 : 'S', 13 : 'M',14:'L',15:'S',16:'S'})
# Replace the values in newly created dataframe and convert that into array.
data_df.replace(key,inplace = True)

data = np.array(data_df)
print(data)

This will be the output:

[['M' 'S' 'S']
['L' 'M' 'L']
['S' 'M' 'M']]