in python how to convert string to float

To convert a string to a float in Python, you can use the float() function. Here’s an example:

my_str = "3.14"
my_float = float(my_str)
print(my_float)

In this example, the float() function is used to convert the string my_str to a floating-point number, which is then assigned to the variable my_float. The resulting my_float is 3.14, which is a float.

Note that if the string cannot be converted to a float, a ValueError will be raised. It’s important to make sure that the string you’re trying to convert to a float actually contains a valid floating-point number.

To convert a string column to a float column in a pandas DataFrame

To convert a string column to a float column in a pandas DataFrame, you can use the astype() method or the to_numeric() function.

Here’s an example of how to use the astype() method:

import pandas as pd

# create a sample dataframe
df = pd.DataFrame({'A': ['1.2', '3.4', '5.6'],
                   'B': ['7.8', '9.0', '1.2']})

# convert the 'A' and 'B' columns to floats
df['A'] = df['A'].astype(float)
df['B'] = df['B'].astype(float)

print(df.dtypes)

In this example, the astype() method is used to convert the ‘A’ and ‘B’ columns of the DataFrame df to floats by specifying float as the argument. The resulting df.dtypes output will show that the ‘A’ and ‘B’ columns are now of type float64.

Here’s an example of how to use the to_numeric() function:

import pandas as pd

# create a sample dataframe
df = pd.DataFrame({'A': ['1.2', '3.4', '5.6'],
                   'B': ['7.8', '9.0', '1.2']})

# convert the 'A' and 'B' columns to floats
df['A'] = pd.to_numeric(df['A'])
df['B'] = pd.to_numeric(df['B'])

print(df.dtypes)

In this example, the to_numeric() function is used to convert the ‘A’ and ‘B’ columns to floats by passing in the series objects containing the strings. The resulting df.dtypes output will show that the ‘A’ and ‘B’ columns are now of type float64.

To convert a string array to a float array using NumPy

To convert a string array to a float array using NumPy, you can use the numpy.asarray() function along with dtype=float. Here’s an example:

import numpy as np

# create a sample string array
string_array = np.array(['1.2', '3.4', '5.6'])

# convert the string array to a float array
float_array = np.asarray(string_array, dtype=float)

print(float_array)

In this example, the numpy.asarray() function is used to convert the string_array into a float array float_array using dtype=float. The resulting float_array output will show that the string values have been successfully converted to their floating-point equivalents.

Note that if any of the values in the string array cannot be converted to a float, a ValueError will be raised. It’s important to make sure that all the string values in the array are valid floating-point numbers.