Python – How to convert only numbers in a mixed list into float?

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You could create a simple utility function that either converts the given value to a float if possible, or returns it as is:

def maybe_float(s):
    try:
        return float(s)
    except (ValueError, TypeError):
        return s

orig_list = ['data', '18', '17', '0']
the_list = [maybe_float(v) for v in orig_list]

And please don’t use names of builtin functions and types such as list etc. as variable names.

Since your data actually has structure instead of being a truly mixed list of strings and numbers, it seems a 4-tuple of (str, float, float, float) is more apt:

data_conv = (data_l[0], *(float(v) for v in data_l[1:]))

or in older Python versions

# You could also just convert each float separately since there are so few
data_conv = tuple([data_l[0]] + [float(v) for v in data_l[1:]])

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