Converting a string to an integer or float

Question

I have the following list:

[[1.01782362e-05 1.93798303e-04 7.96163586e-05 5.08812627e-06
  1.39600188e-05 3.94912873e-04 2.33748418e-04 1.22856018e-05]]

When I return its type, I get:

<class 'str'>

Is the reason for that the scientific notation used for instance (i.e. e-04)?

In this case, how can I convert the above list to an integer or float?

Thanks.

EDIT

The above list snippet comes from this CSV file under the "Feature" column.

What you posted is neither a string nor syntaxtically valid. Please provide a minimal reproducible example. My guess is that the above is surrounded by quote marks that you did not include, but in that case there is no mystery as to why it is a string. — John Coleman
– John Coleman, Commented Nov 30, 2021 at 15:40
I would change your title to say "Converting scientific notation to a float". — Gabriel G.
– Gabriel G., Commented Nov 30, 2021 at 15:40
Does this answer your question? Convert Scientific Notation to Float — nikeros
– nikeros, Commented Nov 30, 2021 at 15:43
I added the CSV file where the data is coming from to my question. — Simplicity
– Simplicity, Commented Nov 30, 2021 at 16:35
Does this answer your question? Parsing the string-representation of a numpy array — Sam Mason
– Sam Mason, Commented Nov 30, 2021 at 18:10

Sam Mason · Accepted Answer · 2021-11-30 18:15:57Z

1

It looks a lot like you have NumPy's string representation of an array. As I linked above, there doesn't seem to be a nice way of parsing this back, but in your case it might not matter, Pandas and Numpy can sort of get there reasonably easily:

import pandas as pd
import numpy as np

# read in the data
df = pd.read_csv("features_thresholds.csv")

# use numpy to parse that column
df.Feature = df.Feature.apply(lambda x: np.fromstring(x[2:-2], sep=' '))

note that the x[2:-2] is trimming off the leading [[ and trailing ]], otherwise it's mostly standard Pandas usage that most data science tutorials will go through.

answered Nov 30, 2021 at 18:15

Sam Mason

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Sam Mason Over a year ago

if you can I'd suggest asking whoever gave you that file to give it to you in some other format that's easier to parse, e.g. a JSON dump of the array would likely be more portable than what you've got

John Coleman · Accepted Answer · 2021-11-30 15:45:51Z

0

What you posted must be part of a string literal:

s = '[[1.01782362e-05 1.93798303e-04 7.96163586e-05 5.08812627e-06 1.39600188e-05 3.94912873e-04 2.33748418e-04 1.22856018e-05]]'

In which case

list(map(float, s.lstrip('[').rstrip(']').split()))

evaluates to

[1.01782362e-05, 0.000193798303, 7.96163586e-05, 5.08812627e-06, 1.39600188e-05, 0.000394912873, 0.000233748418, 1.22856018e-05]

answered Nov 30, 2021 at 15:45

John Coleman

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saravanan saminathan · Accepted Answer · 2021-11-30 15:54:08Z

0

We can use python ast (Abstract Syntax Tree) to process it efficiently

import ast
x = '[[1.01782362e-05 1.93798303e-04 7.96163586e-05 5.08812627e-06 1.39600188e-05 3.94912873e-04 2.33748418e-04 1.22856018e-05]]'
x = ast.literal_eval(x.replace(" ",","))
print(x)

answered Nov 30, 2021 at 15:54

saravanan saminathan

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1 Comment

John Coleman Over a year ago

Using literal_eval is a good idea.

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