Convert string to dict, then access key:values??? How to access data in a <class 'dict'> for Python?
<p>I am having issues accessing data inside a dictionary.  </p>

<blockquote>
  <p>Sys: Macbook 2012 <br>
  Python: Python 3.5.1 :: Continuum Analytics, Inc.</p>
</blockquote>

<p>I am working with a <a href="http://dask.pydata.org/en/latest/dataframe-create.html" rel="nofollow">dask.dataframe</a> created from a csv.  </p>

<h2>Edit Question</h2>

<h1>How I got to this point</h1>

<p>Assume I start out with a Pandas Series:</p>

<pre><code>df.Coordinates
130      {u'type': u'Point', u'coordinates': [-43.30175...
278      {u'type': u'Point', u'coordinates': [-51.17913...
425      {u'type': u'Point', u'coordinates': [-43.17986...
440      {u'type': u'Point', u'coordinates': [-51.16376...
877      {u'type': u'Point', u'coordinates': [-43.17986...
1313     {u'type': u'Point', u'coordinates': [-49.72688...
1734     {u'type': u'Point', u'coordinates': [-43.57405...
1817     {u'type': u'Point', u'coordinates': [-43.77649...
1835     {u'type': u'Point', u'coordinates': [-43.17132...
2739     {u'type': u'Point', u'coordinates': [-43.19583...
2915     {u'type': u'Point', u'coordinates': [-43.17986...
3035     {u'type': u'Point', u'coordinates': [-51.01583...
3097     {u'type': u'Point', u'coordinates': [-43.17891...
3974     {u'type': u'Point', u'coordinates': [-8.633880...
3983     {u'type': u'Point', u'coordinates': [-46.64960...
4424     {u'type': u'Point', u'coordinates': [-43.17986...
</code></pre>

<p>The problem is, this is not a true dataframe of dictionaries.  Instead, it's a column full of strings that LOOK like dictionaries.  Running this show it:</p>

<pre><code>df.Coordinates.apply(type)
130      &lt;class 'str'&gt;
278      &lt;class 'str'&gt;
425      &lt;class 'str'&gt;
440      &lt;class 'str'&gt;
877      &lt;class 'str'&gt;
1313     &lt;class 'str'&gt;
1734     &lt;class 'str'&gt;
1817     &lt;class 'str'&gt;
1835     &lt;class 'str'&gt;
2739     &lt;class 'str'&gt;
2915     &lt;class 'str'&gt;
3035     &lt;class 'str'&gt;
3097     &lt;class 'str'&gt;
3974     &lt;class 'str'&gt;
3983     &lt;class 'str'&gt;
4424     &lt;class 'str'&gt;
</code></pre>

<p><strong>My Goal</strong>: Access the <code>coordinates</code> key and value in the dictionary.  That's it. But it's a <code>str</code> </p>

<p>I converted the strings to dictionaries using <code>eval</code>.</p>

<pre><code>new = df.Coordinates.apply(eval)
130      {'coordinates': [-43.301755, -22.990065], 'typ...
278      {'coordinates': [-51.17913026, -30.01201896], ...
425      {'coordinates': [-43.17986794, -22.91000096], ...
440      {'coordinates': [-51.16376782, -29.95488677], ...
877      {'coordinates': [-43.17986794, -22.91000096], ...
1313     {'coordinates': [-49.72688407, -29.33757253], ...
1734     {'coordinates': [-43.574057, -22.928059], 'typ...
1817     {'coordinates': [-43.77649254, -22.86940539], ...
1835     {'coordinates': [-43.17132318, -22.90895217], ...
2739     {'coordinates': [-43.1958313, -22.98755333], '...
2915     {'coordinates': [-43.17986794, -22.91000096], ...
3035     {'coordinates': [-51.01583481, -29.63593292], ...
3097     {'coordinates': [-43.17891379, -22.96476163], ...
3974     {'coordinates': [-8.63388008, 41.14594453], 't...
3983     {'coordinates': [-46.64960938, -23.55902666], ...
4424     {'coordinates': [-43.17986794, -22.91000096], ...
</code></pre>

<p>Next I text the type of object and get:</p>

<pre><code>130      &lt;class 'dict'&gt;
278      &lt;class 'dict'&gt;
425      &lt;class 'dict'&gt;
440      &lt;class 'dict'&gt;
877      &lt;class 'dict'&gt;
1313     &lt;class 'dict'&gt;
1734     &lt;class 'dict'&gt;
1817     &lt;class 'dict'&gt;
1835     &lt;class 'dict'&gt;
2739     &lt;class 'dict'&gt;
2915     &lt;class 'dict'&gt;
3035     &lt;class 'dict'&gt;
3097     &lt;class 'dict'&gt;
3974     &lt;class 'dict'&gt;
3983     &lt;class 'dict'&gt;
4424     &lt;class 'dict'&gt;
</code></pre>

<p>If I try to access my dictionaries:
new.apply(lambda x: x['coordinates']</p>

<pre><code>---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
&lt;ipython-input-71-c0ad459ed1cc&gt; in &lt;module&gt;()
----&gt; 1 dfCombined.Coordinates.apply(coord_getter)

/Users/linwood/anaconda/envs/dataAnalysisWithPython/lib/python3.5/site-packages/pandas/core/series.py in apply(self, func, convert_dtype, args, **kwds)
   2218         else:
   2219             values = self.asobject
-&gt; 2220             mapped = lib.map_infer(values, f, convert=convert_dtype)
   2221 
   2222         if len(mapped) and isinstance(mapped[0], Series):

pandas/src/inference.pyx in pandas.lib.map_infer (pandas/lib.c:62658)()

&lt;ipython-input-68-748ce2d8529e&gt; in coord_getter(row)
      1 import ast
      2 def coord_getter(row):
----&gt; 3     return (ast.literal_eval(row))['coordinates']

TypeError: 'bool' object is not subscriptable
</code></pre>

<p>It's some type of class, because when I run <code>dir</code> I get this for one object:</p>

<pre><code>new.apply(lambda x: dir(x))[130]
130           __class__
130        __contains__
130         __delattr__
130         __delitem__
130             __dir__
130             __doc__
130              __eq__
130          __format__
130              __ge__
130    __getattribute__
130         __getitem__
130              __gt__
130            __hash__
130            __init__
130            __iter__
130              __le__
130             __len__
130              __lt__
130              __ne__
130             __new__
130          __reduce__
130       __reduce_ex__
130            __repr__
130         __setattr__
130         __setitem__
130          __sizeof__
130             __str__
130    __subclasshook__
130               clear
130                copy
130            fromkeys
130                 get
130               items
130                keys
130                 pop
130             popitem
130          setdefault
130              update
130              values
Name: Coordinates, dtype: object
</code></pre>

<p><strong>My Problem</strong>: I just want to access the dictionary.  But, the object is <code>&lt;class 'dict'&gt;</code>.  How do I covert this to a regular dict or just access the key:value pairs?</p>

<p>Any ideas??</p>

<p>My first instinct is to use the <code>json.loads</code> to cast the strings into dicts. But the example you've posted does not follow the json standard since it uses single instead of double quotes. So you have to convert the strings first. </p>

<p>A second option is to just use regex to parse the strings. If the dict strings in your actual DataFrame do not exactly match my examples, I expect the regex method to be more robust since lat/long coords are fairly standard.</p>

<pre><code>import re
import pandasd as pd

df = pd.DataFrame(data={'Coordinates':["{u'type': u'Point', u'coordinates': [-43.30175, 123.45]}",
    "{u'type': u'Point', u'coordinates': [-51.17913, 123.45]}"],
    'idx': [130, 278]})


##
# Solution 1- use json.loads
##

def string_to_dict(dict_string):
    # Convert to proper json format
    dict_string = dict_string.replace("'", '"').replace('u"', '"')
    return json.loads(dict_string)

df.CoordDicts = df.Coordinates.apply(string_to_dict)
df.CoordDicts[0]['coordinates']
#&gt;&gt;&gt; [-43.30175, 123.45]


##
# Solution 2 - use regex
##
def get_lat_lon(dict_string):
    # Get the coordinates string with regex
    rs = re.search("(\-?\d+(\.\d+)?),\s*(\-?\d+(\.\d+)?)", dict_string).group()
    # Cast to floats
    coords = [float(x) for x in rs.split(',')]
    return coords

df.Coords = df.Coordinates.apply(get_lat_lon)
df.Coords[0]
#&gt;&gt;&gt; [-43.30175, 123.45]
</code></pre>

python pandas dictionary data-manipulation dask