Python, class attribute error

Question

I have a set of code that looks like this:

class DataFilter:

    def __init__(self, csvData):
        # converts csv string data to float lists, if possible
        data = []
        for line in csvData:
            try:
                line = line.split(',')
            except:
                print(line)
                return

            for i in range( len(line) ):
                try:
                    line[i] = float(line[i])
                except ValueError:
                    pass
            data.append(line)
        self.data = data

    def find_depth_index(self, depth):
        for index, line in enumerate( self.data ):
            if line[1] > depth:
                return index

    def remove_above_depth(self, depth):
        index = self.find_depth_index( depth )
        return self.data[ index: ]

    def remove_beyond_depth(self, depth):
        index = self.find_depth_index(depth)
        return self.data[ :index ]

data = DataFilter(data).remove_above_depth(SURF_CASING_DEPTH)
print('-----------------------')
data = DataFilter(data).remove_beyond_depth(VERTICAL_SEC_DEPTH)

Then it give me an error:

  File "C:/Users/Eric Soobin Kim/PycharmProjects/untitled/RAPID_use_filtered_data.py", line 35, in remove_beyond_depth
    def remove_beyond_depth(self, depth):
  File "C:/Users/Eric Soobin Kim/PycharmProjects/untitled/RAPID_use_filtered_data.py", line 26, in find_depth_index
    def find_depth_index(self, depth):
AttributeError: 'DataFilter' object has no attribute 'data'

The thing that I don't understand is that, it ran without a problem for the line:

data = DataFilter(data).remove_above_depth(SURF_CASING_DEPTH)

but its not working for,

data = DataFilter(data).remove_beyond_depth(VERTICAL_SEC_DEPTH)

I think my first filtering somehow alters elements in __ini__(), but i don't know what's going on. Why is this happening, and how can i fix it?

Looks like you are hitting the return in the except block and self.data will never be set. — Klaus D.
– Klaus D., Commented Mar 5, 2018 at 5:28
@KlausD. I edited my code. I see what you are saying. But in my code, there was no exception raised, so return was not the source of error here. Sorry for the confusion — Eric Kim
– Eric Kim, Commented Mar 5, 2018 at 5:47
@Eric Kim Can you post the whole code? What values does data have initially? — Monty _s Flying Circus
– Monty _s Flying Circus, Commented Mar 5, 2018 at 5:52

Monty _s Flying Circus · Accepted Answer · 2018-03-05 05:38:19Z

1

You've reassigned data to be equal to something other than what you want.

data = DataFilter(data).remove_above_depth(SURF_CASING_DEPTH)

This means that now you've lost the pointer to data that you once had. Might I suggest making a copy like

new_data = DataFilter(data).remove_above_depth(SURF_CASING_DEPTH)
new_data2 = DataFilter(data).remove_beyond_depth(VERTICAL_SEC_DEPTH)

This way you still have the reference to the old data variable

edited Mar 5, 2018 at 5:38

answered Mar 5, 2018 at 5:20

Monty _s Flying Circus

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7 Comments

Aran-Fey Over a year ago

This is the correct answer, but it's severely lacking in explanation. How does changing the value of a variable prevent an instance attribute from being created?

Monty _s Flying Circus Over a year ago

@Aran-Fey How's that?

Eric Kim Over a year ago

Im not sure if this is what I want, because I am supposed to apply two filters to my data. So, first I filter the data points that doesn't fit my first filter, and then using the filtered data, I apply my second filter.

Aran-Fey Over a year ago

I don't see a difference. There's no explanation why the data attribute isn't being created. In fact I'm starting to wonder if you misunderstood the question.

Eric Kim Over a year ago

@frank No, there was no exception raised in my code. I deleted return in my init function, and it ran fine without raising exception.

|

Стёпа Кашкаров · Accepted Answer · 2018-03-05 05:25:20Z

0

Object has no attribute data because you didnt give it the attribute. atributes are defined by making writing: self.object = [] instead of: object = []

answered Mar 5, 2018 at 5:25

Стёпа Кашкаров

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1 Comment

Aran-Fey Over a year ago

"you didnt give it the attribute" Yes they did: self.data = data.

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