Identify the strings in python array

Question

I have a data similar to,

import numpy as np
A = np.array( [['1','2','3'], ['a','3','5']] )

Now I want to identify the cell address of 'a'. I have tried the following code for that purpose,

for i in range(0,2):
    for j in range(0,3):
        if (type(float(A[i,j])) == float):
            print(str(i)+str(j))

since, 'a' can't be converted into floating point it shows the following error.

00

01

02

Traceback (most recent call last):

File "", line 3, in

if (type(float(A[i,j])) == float):

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

Please help. Thank you in advance.

Don't you need to use `A[i][j]` or is that some fancy `numpy` magic? — Sumner Evans, Nov 20 '17 at 18:41
Your data is going to be just one character? Then you could use `isdigit` and so https://docs.python.org/3/library/stdtypes.html — fernand0, Nov 20 '17 at 18:41
@SumnerEvans the `__getitem__` of `numpy` arrays accepts tuples! — timgeb, Nov 20 '17 at 18:45
*everything* is a string in your array. Why are you even using `numpy` here? — juanpa.arrivillaga, Nov 20 '17 at 18:45
@timgeb, that's cool! I've never used numpy before, so that's really neat. — Sumner Evans, Nov 20 '17 at 18:46
@juanpa.arrivillaga I think OP is trying to differentiate between things that can and cannot be coerced to numbers. I also don't really see why it matters what they are using numpy for — Robbie Milejczak, Nov 20 '17 at 18:47
You can check the type of variable with `isinstance(A[i,j], float)` — Alexey, Nov 20 '17 at 18:48
@RobbieMilejczak right, well, my point is that the OP should be *precise*, since taken at face value, that is not what they are asking. I made the comment about `numpy` because this doesn't seem like a good use case for `numpy`, i.e. the use of strings. — juanpa.arrivillaga, Nov 20 '17 at 18:48

score 1 · Accepted Answer · answered Nov 20 '17 at 18:50

You can try this

import numpy as np

def is_number(s):
   try:
    int(s)
    return True
   except ValueError:
    return False

A = np.array( [['1','2','3'], ['a','3','5']] )

for i in range(0,2):
    for j in range(0,3):
        if not is_number(A[i][j]):
            print i , j

Identify the strings in python array

1 Answers1