putting int/float from file into a dictionary

Question

I like to put some values from a csv file into a dict. An example is:

TYPE, Weldline

Diam, 5.0

Num of Elems, 4

and I end up after reading into a dictionary (for later use in an API) in:

 {'TYPE':'Weldline' , 'Diam':'5.0','Num of Elems':'4'}

Since the API expects a dictionary i provided all the necessary keywords like 'TYPE', 'Diam', ... according to the API doc.

The problem I have is, that the API expects a float for Diam and an integer for Num of Elems

Since I have a large number of entries: is there an simple automatic way for string conversion into float or int? Or do I have to write something on my own?

Duplicate? http://stackoverflow.com/questions/5316720/python-how-to-convert-a-list-of-dictionaries-values-into-int-float-from-string — Chris_Rands, Sep 02 '16 at 09:15
Provide keywords in form of dictionary where you link keyword to function that will convert value. — Tomasz Plaskota, Sep 02 '16 at 09:20
@Chris_Rands I think the question is: How best to determine whether to use `int` or `float`? — tobias_k, Sep 02 '16 at 09:24

turkus · Accepted Answer · 2016-09-02T09:35:53.977

1

You can use literal_eval

This can be used for safely evaluating strings containing Python values from untrusted sources without the need to parse the values oneself. It is not capable of evaluating arbitrarily complex expressions, for example involving operators or indexing.

import ast

_dict = {}

with open('file.txt', 'r') as f:
    for line in f.readlines():
        if line.strip():
            key, value = line.split(',')
            value = value.strip()
            try:
                _dict[key] = ast.literal_eval(value)
            except ValueError:
                _dict[key] = value

print _dict

edited Sep 02 '16 at 09:35

answered Sep 02 '16 at 09:22

turkus

4,637
2
24
28

It's better to suggest `ast.literal_eval` than `eval`. I did not down-vote you, though. – juanpa.arrivillaga Sep 02 '16 at 09:25

score 0 · Answer 2 · answered Sep 02 '16 at 09:33

0

Also try this it seems more simple.

import csv,ast
    with open('file.csv', mode='r') as file:
    reader = csv.reader(file)
    mydict = {rows[0]:ast.literal_eval(rows[1]) for rows in reader}
print mydict

answered Sep 02 '16 at 09:33

florex

943
7
9

Does not work, the "strings" in the file are not quoted. – tobias_k Sep 02 '16 at 09:48
Thats what i found also... so any other idea? – Sep 02 '16 at 11:34
@Bruno See turkus answer: `try` to evaluate the string, and if that does not work, just take it as is. – tobias_k Sep 02 '16 at 12:40

score 0 · Answer 3 · answered Sep 02 '16 at 12:46

Now I tried this:

                key   = Line[0].strip()
                value = Line[1].strip()
                try:
                    value = int(Line[1].strip())
                except ValueError:
                    try: 
                        value = float(Line[1].strip())
                    except ValueError:
                        value = Line[1].strip()

            Entry[key]=value

It seems it works fine...

putting int/float from file into a dictionary

3 Answers3