CODEWITHSUNDEEP
pythondecimalnotation
Loops
Loops

Reputation: 611

Convert Scientific Notation to Float

Encountered a problem whereby my JSON data gets printed as a scientific notation instead of a float.

import urllib2
import json
import sys

url = 'https://bittrex.com/api/v1.1/public/getmarketsummary?market=btc-quid'
json_obj = urllib2.urlopen(url)
QUID_data = json.load(json_obj)

QUID_MarketName_Trex = QUID_data["result"][0]["MarketName"][4:9]
QUID_Last_Trex = QUID_data["result"][0]["Last"]
QUID_High_Trex = QUID_data["result"][0]["High"]
QUID_Low_Trex = QUID_data["result"][0]["Low"]
QUID_Volume_Trex = QUID_data["result"][0]["Volume"]
QUID_BaseVolume_Trex = QUID_data["result"][0]["BaseVolume"]
QUID_TimeStamp_Trex = QUID_data["result"][0]["TimeStamp"]
QUID_Bid_Trex = QUID_data["result"][0]["Bid"]
QUID_Ask_Trex = QUID_data["result"][0]["Ask"]
QUID_OpenBuyOrders_Trex = QUID_data["result"][0]["OpenBuyOrders"]
QUID_OpenSellOrders_Trex = QUID_data["result"][0]["OpenSellOrders"]
QUID_PrevDay_Trex = QUID_data["result"][0]["PrevDay"]
QUID_Created_Trex = QUID_data["result"][0]["Created"]
QUID_Change_Trex = ((QUID_Last_Trex - QUID_PrevDay_Trex)/ QUID_PrevDay_Trex)*100
QUID_Change_Var = str(QUID_Change_Trex)
QUID_Change_Final = QUID_Change_Var[0:5] + '%'

print QUID_Last_Trex

It prints the following value; 1.357e-05. I need this to be a float with 8 chars behind the decimal (0.00001370)

As you can see here --> https://i.sstatic.net/qqhNc.jpg, my GUI displays the first row correct (using the exact same code).

Upvotes: 56

Views: 165187

Answers (3)

Martijn Pieters
Martijn Pieters

Reputation: 1121168

You are looking at the default str() formatting of floating point numbers, where scientific notation is used for sufficiently small or large numbers.

You don't need to convert this, the value itself is a proper float. If you need to display this in a different format, format it explicitly:

>>> print(0.00001357)
1.357e-05
>>> print(format(0.00001357, 'f'))
0.000014
>>> print(format(0.00001357, '.8f'))
0.00001357

Here the f format always uses fixed point notation for the value. The default precision is 6 digits; the .8 instructs the f formatter to show 8 digits instead.

In Python 3, the default string format is essentially the same as format(fpvalue, '.16g'); the g format uses either a scientific or fixed point presentation depending on the exponent of the number. Python 2 used '.12g'.

Upvotes: 85

Roman
Roman

Reputation: 21757

There are some approaches:

#1 float(...) + optionally round() or .format()

x = float(1.357e-05)
round(x, 6)
"{:.8f}".format(x)

#2 with decimal class

import decimal

tmp = decimal.Decimal('1.357e-05')
print('[0]', tmp)
# [0] 0.00001357

tmp = decimal.Decimal(1.357e-05)
print('[1]', tmp)
# [1] 0.0000135700000000000005188384444299032338676624931395053863525390625

decimal.getcontext().prec = 6
tmp = decimal.getcontext().create_decimal(1.357e-05)
print('[2]', tmp)
# [2] 0.0000135700

#3 with .rstrip(...)

x = ("%.17f" % n).rstrip('0').rstrip('.')

Note: there are counterparts to %f:
%f shows standard notation
%e shows scientific notation
%g shows default (scientific if 5 or more zeroes)

Upvotes: 4

Evgeny Prokurat
Evgeny Prokurat

Reputation: 734

You can use print formatting:

x = 1.357e-05    
print('%f' % x)

Edit:

print('%.08f' % x)

Upvotes: 7

Related Questions