Pandas (34)

How to change column values when importing csv to a dataframe?

# 1: Using converter parameter
df = pd.read_csv('https://raw.githubusercontent.com/selva86/datasets/master/BostonHousing.csv', 
                 converters={'medv': lambda x: 'High' if float(x) > 25 else 'Low'})


# 2: Using csv reader
import csv
with open('BostonHousing.csv', 'r') as f:
    reader = csv.reader(f)
    out = []
    for i, row in enumerate(reader):
        if i > 0:
            row[13] = 'High' if float(row[13]) > 25 else 'Low'
        out.append(row)

df = pd.DataFrame(out[1:], columns=out[0])
print(df.head())

# output
                   crim    zn indus chas                  nox  \
0               0.00632  18.0  2.31    0   0.5379999999999999   
1               0.02731   0.0  7.07    0                0.469   
2               0.02729   0.0  7.07    0                0.469   
3  0.032369999999999996   0.0  2.18    0  0.45799999999999996   
4               0.06905   0.0  2.18    0  0.45799999999999996   

                  rm   age     dis rad  tax ptratio       b lstat  medv  
0              6.575  65.2    4.09   1  296    15.3   396.9  4.98   Low  
1              6.421  78.9  4.9671   2  242    17.8   396.9  9.14   Low  
2              7.185  61.1  4.9671   2  242    17.8  392.83  4.03  High  
3  6.997999999999999  45.8  6.0622   3  222    18.7  394.63  2.94  High  
4              7.147  54.2  6.0622   3  222    18.7   396.9  5.33  High