Python importing a text file and converting string to float

Question

I have encountered some value error when input txt file into python.

the txt file called "htwt.txt", and contain the below data:

When I typed the below code, and value errors are occurred.

import numpy as np

import pandas as pd

import matplotlib.pyplot as plt

import os


import statsmodels.api as sm

from statsmodels.formula.api import ols


os.chdir("/Users/James/Desktop/data/")

data1=np.loadtxt("htwt.txt") 

df1=pd.DataFrame(data1)

ValueError: could not convert string to float: 'Ht'

May I know what should the correct code so that it can be converted to the data frame? thanks.

Rishabh Kumar · Accepted Answer · 2021-02-27 14:11:21Z

1

Pandas read_csv is enough

import pandas as pd
import os
os.chdir("/Users/James/Desktop/data/")

df1 = pd.read_csv("htwt.txt",sep=' ')

Output:

>>> df1
      Ht    Wt
0  169.6  71.2
1  166.8  58.2
2  157.1  56.0
3  181.1  64.5
4  158.4  53.0
5  165.6  52.4
6  166.7  56.8
7  156.5  49.2
8  168.1  55.6
9  165.3  77.8

Checking the types:

>>> df.info()
<class 'pandas.core.frame.DataFrame'>
RangeIndex: 10 entries, 0 to 9
Data columns (total 2 columns):
 #   Column  Non-Null Count  Dtype  
---  ------  --------------  -----  
 0   Ht      10 non-null     float64
 1   Wt      10 non-null     float64
dtypes: float64(2)
memory usage: 288.0 bytes

answered Feb 27, 2021 at 14:11

Rishabh Kumar

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Comments

aksonai · Accepted Answer · 2021-02-27 14:30:09Z

1

Like mentioned above pandas read_csv works, but if you insist on using np.loadtxt you can skip the first row which can't be converted to a float. You can do:

data1 = np.loadtxt("htwt.txt", skiprows=1)

answered Feb 27, 2021 at 14:30

aksonai

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1 Comment

Rishabh Kumar Over a year ago

Please see OP's comment on Alexander's answer.

Alexander Kosik · Accepted Answer · 2021-02-27 14:06:06Z

0

The first row in your text file has alphanumeric characters: "Ht Wt". These characters cannot be converted to a floating point number. Remove the first row and you should be fine.

answered Feb 27, 2021 at 14:06

Alexander Kosik

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1 Comment

Kam Hung Wong Over a year ago

Hi Alexander, any ways that do not need to remove the first row but change them into column name when import them? thanks a lot!

Salma Elshahawy · Accepted Answer · 2021-02-28 00:50:47Z

0

#for skipping of the first line
file1 = open("hwwt.txt")

lines = file1.readlines()[1:]
for line in lines:
    print(line.rstrip())

OUTPUT
#otherwise you can use read_csv which is enough

edited Feb 28, 2021 at 0:50

Salma Elshahawy

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answered Feb 27, 2021 at 14:29

Shishir Regmi

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1 Comment

Mark Rotteveel Over a year ago

Please don't post only code as answer, but also provide an explanation what your code does and how it solves the problem of the question. Answers with an explanation are usually more helpful and of better quality, and are more likely to attract upvotes.

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