# How to convert an array of strings to an array of floats in numpy?

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## How to convert an array of strings to an array of floats in numpy?

### Accepted Answer

Well, if you're reading the data in as a list, just do `np.array(map(float, list_of_strings))`

(or equivalently, use a list comprehension). (In Python 3, you'll need to call `list`

on the `map`

return value if you use `map`

, since `map`

returns an iterator now.)

However, if it's already a numpy array of strings, there's a better way. Use `astype()`

.

```
import numpy as np
x = np.array(['1.1', '2.2', '3.3'])
y = x.astype(np.float)
```

2017/06/30

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You can use this as well

```
import numpy as np
x=np.array(['1.1', '2.2', '3.3'])
x=np.asfarray(x,float)
```

2017/09/17

Another option might be numpy.asarray:

```
import numpy as np
a = ["1.1", "2.2", "3.2"]
b = np.asarray(a, dtype=np.float64, order='C')
```

For Python 2*:

```
print a, type(a), type(a[0])
print b, type(b), type(b[0])
```

resulting in:

```
['1.1', '2.2', '3.2'] <type 'list'> <type 'str'>
[1.1 2.2 3.2] <type 'numpy.ndarray'> <type 'numpy.float64'>
```

2018/06/12

If you have (or create) a single string, you can use **np.fromstring**:

```
import numpy as np
x = ["1.1", "2.2", "3.2"]
x = ','.join(x)
x = np.fromstring( x, dtype=np.float, sep=',' )
```

Note, `x = ','.join(x)`

transforms the x array to string `'1.1, 2.2, 3.2'`

. If you read a line from a txt file, each line will be already a string.

2017/10/05

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