Python : save dictionaries through numpy.save

Question

I have a large data set (millions of rows) in memory, in the form of numpy arrays and dictionaries. Once this data is constructed I want to store them into files; so, later I can load these files into memory quickly, without reconstructing this data from the scratch once again. np.save and np.load functions does the job smoothly for numpy arrays. But I am facing problems with dict objects. See below sample. d2 is the dictionary which was loaded from the file. See #out[28] it has been loaded into d2 as a numpy array, not as a dict. So further dict operations such as get are not working. Is there a way to load the data from the file as dict (instead of numpy array) ? ``` In [25]: d1={'key1':[5,10], 'key2':[50,100]} In [26]: np.save("d1.npy", d1) In [27]: d2=np.load("d1.npy") In [28]: d2 Out[28]: array({'key2': [50, 100], 'key1': [5, 10]}, dtype=object) In [30]: d1.get('key1') #original dict before saving into file Out[30]: [5, 10] In [31]: d2.get('key2') #dictionary loaded from the file…

Accepted Answer

It's a structured array. Use `d2.item()` to retrieve the actual dict object first:

```
import numpy as np

d1={'key1':[5,10], 'key2':[50,100]}
np.save("d1.npy", d1)
d2=np.load("d1.npy")
print d1.get('key1')
print d2.item().get('key2')
```

result:

```
[5, 10]
[50, 100]
```

Python : save dictionaries through numpy.save

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