I have been using python for my assignments for past few days. I noticed one strange thing that -
- When I convert string to float - it gives exactly same number of digits that were in string.
When I put this number in file using struct.pack() with 4 bytes floats and read it back using struct.unpack(), it gives a number not exactly same but some longer string which I expect if as per the floating point storage
Ex. - String - 0.931973
Float num - 0.931973
from file - 0.931972980499 (after struct pack and unpack into 4 bytes)
So I am unable to understand how python actually stored my number previously when I read it from string.
EDIT Writing the float (I think in python 2.7 on ubuntu its other way around, d- double and f-float)
buf = struct.pack("f", float(self.dataArray[i])) fout.write(buf) Query -
buf = struct.pack("f", dataPoint) dataPoint = struct.unpack("f", buf)[0] node = root while(node.isBPlusNodeLeaf()) == False: node = node.findNextNode(dataPoint) findNextNode -
def findNextNode(self, num): i = 0 for d in self.dataArray: if float(num) > float(d): i = i + 1 continue else: break ptr = self.pointerArray[i] #open the node before passing on the pointer to it out, tptr = self.isNodeAlive(ptr) if out == False: node = BPlusNode(name = ptr) node.readBPlusNode(ptr) return node else: return BPlusNode.allNodes[tptr] once I reach to leaf it reads the leaf and check if the datapoint exist there.
for data in node.dataArray: if data == dataPoint: return True return False So in this case it returns unsuccessful search for datapoint - 0.931972980499 which is there although.
While following code works fine -
for data in node.dataArray: if round(float(data), 6) == dataPoint: return True return False I am not able to understand why this is happening
