How to convert neo4j return types to python types

问题:

I am using py2neo and I would like to extract the information from query returns so that I can do stuff with it in python. For example, I have a DB containing three "Person" nodes:

for num in graph.cypher.execute("MATCH (p:Person) RETURN count(*)"): print num

outputs:

>> count(*)

3

Sorry for shitty formatting, it looks essentially the same as a mysql output. However, I would like to use the number 3 for computations, but it has type py2neo.cypher.core.Record. How can I convert this to a python int so that I can use it? In a more general sense, how should I go about processing cypher queries so that the data I get back can be used in Python?

回答1:

graph.cypher.execute() returns a RecordList containing multiple Records. Each Record corresponds to a single line of the result of your Cypher query.

Your RETURN count(*) query returns only one line, so the for num in ... loop will only touch one Record in your RecordList.

To get data from the columns of a record, you can use indices or column names:

for num in ... :
    your_count = num[0] # gets the first column

This should be an int, but you can now convert it to whatever you need with float() or int().

---

Your query returns only one line with one column. You can shorten it to:

your_count = graph.cypher.execute("MATCH (p:Person) RETURN count(*)")[0][0]

The first [0] gets the first Record of your resulting RecordList and the second [0] gets the first column of the Record.

Have a look at: http://py2neo.org/2.0/cypher.html#records

回答2:

can you int(), float() str() on the __str__() method that looks to be outputting the value you want in your example?