Replace "a**b" to pow(a,b) [duplicate] - sympy
This question already has an answer here:
Replace ** with Math.pow in SymPy
(1 answer)
Closed 5 years ago.
For example, I have the following code:
import sympy as sp
t = sp.Symbol("t")
f = t**2
print(f)
Output: t**2
Can I get output pow(t,2), using sympy?
Thank you.
you could try to hack the string printer:
from sympy.printing import StrPrinter
StrPrinter._print_Pow = lambda self, expr: "pow(%s, %s)" % (self._print(expr.base), self._print(expr.exp))
That is, this overwrites the method _print_Pow in the class StrPrinter, which is responsible for printing the string form of Pow objects.
Related
What is difference between List.from and List.add [duplicate]
This question already has answers here: In Dart, what's the difference between List.from and .of, and between Map.from and .of? (3 answers) Closed 1 year ago. sir, I am working on flutter. I want to know the difference between both codes. points = List.add(DrawingArea( point: details.localPosition, areaPaint: Paint() ..strokeCap = StrokeCap.round ..blendMode = BlendMode.clear ..color = Colors.transparent ..isAntiAlias = true ..strokeWidth = strokeWidth)) points = List.from(points)..add(DrawingArea( point: details.localPosition, areaPaint: Paint() ..strokeCap = StrokeCap.round ..blendMode = BlendMode.clear ..color = Colors.transparent ..isAntiAlias = true ..strokeWidth = strokeWidth))
List.add adds a single entry, List.from creates a list from another list (multiples entries)
Python: how to keep leading zeros with dataframe.to_csv [duplicate]
This question already has answers here:
Pandas read_csv dtype leading zeros
(5 answers)
Import pandas dataframe column as string not int
(3 answers)
Closed 5 years ago.
There is a dataframe (df1) like as following after I read the data from txt file:
name l1 l2
a 00000 00000
b 00010 00002
c 00000 01218
When I use the python code as following:
dataframe.to_csv('test.csv', index= False)
Then I use the following code to read:
df = pd.read_csv('test.csv')
I found the dataframe is being df2 as following
name l1 l2
a 0 0
b 10 2
c 0 1218
But I want to keep the leading zero in the dataframe like df1.
Thanks!
The leading zeros are being removed because Pandas is implicitly converting the values to integer types. You want to read the data as string types, which you can do by specifying dtype=str:
pd.read_csv('test.csv', dtype=str)
Update as it helps others:
To have most or selective columns as str, one can do this:
# lst of column names which needs to be string
lst_str_cols = ['prefix', 'serial']
# use dictionary comprehension to make dict of dtypes
dict_dtypes = {x : 'str' for x in lst_str_cols}
# use dict on dtypes
pd.read_csv('sample.csv', dtype=dict_dtypes)
python: why I got different results when I count frequency within intervals？ [duplicate]
This question already has answers here:
How to remove items from a list while iterating?
(25 answers)
Closed 5 years ago.
The following code is a program aimed to count the frequency within the unequal length intervals in a large data set. The two list "snp" and "bin_list" are test data. And I have to program my code as the following show.
I have a problem that the results were different when used "continue" and "snp.remove(site)" in the codes.
When using "continue" in the codes, I got the following results:
Potri.001G000300up1k 26
Potri.001G000400down1k 26
Potri.001G000300part2 5
However I got the different results when using "snp.remove(site)" in the codes:
Potri.001G000300up1k 26
Potri.001G000400down1k 25
Potri.001G000300part2 5
Actually, the 1st results were right with low speed while the 2nd results were a bit of wrong with high speed.
So, my question is that how can I fix the bug when using "snp.remove(site)" in the codes?
And I use the python 2.7.12.
Note: I have to iterate over the list "snp" every loop.
#!/usr/bin/env python
def locateBin(Start, End, site):
return site >= Start and site <= End
snp = ['17', '24', '31', '36', '38', '43', '45', '50', '52', '58', '86', '224', '306', '369', '663', '665', '668', '740', '811', '844', '891', '942', '1059', '1097', '1186', '1371', '1437', '1458', '1487', '1537', '1571', '1720', '1853', '2066', '2238', '2292', '2296', '2332', '2367', '2387', '2483', '2585', '2772', '2856', '2935', '2944', '2966', '2967', '2991', '2992', '3048', '3166', '3211', '3241', '3280', '3350', '3351', '3367', '3373', '3378', '3406', '3449', '3454', '3533', '3573', '3621', '3623', '3643', '3644', '3697', '3745', '3757', '3822', '3867', '3893', '3949', '4094', '4142', '4149', '4260', '4457', '4462', '4511', '4528', '4535', '4622', '4719', '4722', '4775', '4790', '4801', '4863', '4873', '4879', '4928', '5044', '5454', '5498', '5557', '5584', '5805', '6215', '6231', '6243', '6293', '6346', '6365', '6401', '6421', '6616', '6812', '6861', '6925', '7023', '7126', '7341', '7342', '7369', '7412', '7413', '7483', '7501', '7645', '7679', '7681', '7799', '7828', '7896', '7928', '7944', '7950', '7971', '8002', '8003', '8038', '8058', '8092', '8134', '8213', '8224', '8275', '8292', '8323', '8378', '8444', '8481', '8498', '8499', '8504', '8556', '8616', '8660', '8676', '8710', '8773', '8817', '9158', '9228', '9232', '9302', '9321', '9340', '9383', '9429', '9538', '9602', '9691', '9723', '9880', '9914', '10044', '10046', '10068', '10073', '10176', '10192', '10237', '10241', '10300', '10368', '10618', '10742', '10835', '10959', '11025', '11028', '11260', '11275', '11528', '11912', '11986', '12062', '12095', '12347', '12366', '12513', '12560', '12592', '12648']
bin_list = [['Potri.001G000300up1k', 'Chr01', '7391', '8391'], ['Potri.001G000400down1k', 'Chr01', '7391', '8391'], ['Potri.001G000300part2', 'Chr01', '8625', '8860']]
index = 0
count_list = []
while index < len(bin_list):
num = 0
el = bin_list[index]
for site in snp:
if int(site) < int(el[2]):
continue
#snp.remove(site)
elif locateBin(int(el[2]), int(el[3]), int(site)):
num += 1
else:
count_list.append([el[0], num])
break
index += 1
for line in count_list:
print("%s\t%s\n" % (line[0], line[1])),
You generally shouldn't modify the list while iterating over it. An easy fix is to make a copy of it for iteration (for site in snp[:]:) snp[:] creates a copy of the list.
How to extract numerator and denominator from polynomial without evaluating?
I have the following expression
A=Symbol('A')
x=Symbol('x')
B=Symbol('B')
C=Symbol('C')
D=Symbol('D')
expression=((A**x-B-C)/(D-1))*(D-1)
n,d=fraction(expression)
I am getting following result:
n=A**x-B-C
d=1
My expected result is
n=(A**x-B-C)*(D-1)
d=(D-1)
Is there way in sympy or need to write customize function to handle that
Use UnevaluatedExpr() to prevent the expression from being evaluated.
from sympy import symbols, fraction, UnevaluatedExpr
A,x,B,C,D = symbols('A x B C D')
expression = (A**x-B-C)/(D-1)*UnevaluatedExpr(D-1)
n,d = fraction(expression)
print(n)
print(d)
This returns
(A**x - B - C)*(D - 1)
D - 1
See the Sympy Advanced Expression Manipulation doc page for more details.
Python 2.7: set variable name [duplicate]
This question already has answers here: How can you dynamically create variables? [duplicate] (8 answers) Closed 7 years ago. I would like to set the variable name in a for loop, like: for i in range(5): namei = i # this is a variable name It will give me: name0 = 0 name1 = 1 name2 = 2 name3 = 3 name4 = 4 does anyone know how to do that? Thank you!
Instead of having 5 separate variables, you should use an array. Eg. name = [] #Create an empty array for i in range(5): name.append(i) #Add each value to your array This will leave you with name[0] = 0 name[1] = 1 ... etc.