What is difference between List.from and List.add [duplicate] - list
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)
Related
Replace "a**b" to pow(a,b) [duplicate]
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.
Limit sliderInput to a subrange [duplicate]
This question already has answers here: R shiny sliderInput with restricted range (2 answers) Closed 5 years ago. I have a sliderInput() ranging from 0 to 100 and would like to limit it to only allow values from 0 to 10. Is there a way to achieve that? Note: This may seem like a silly request (just set max = 10 to shorten the scale) but it's for good reason I would like to maintain the full scale.
You can do something link this:
rm(list = ls())
library(shiny)
ui <-basicPage(
sliderInput("slider1", "Slider 1: ", min = 0, max = 100, value = 0, step=1)
)
server <- function(input, output,session) {
observeEvent(input$slider1,{
if(input$slider1 > 10){
updateSliderInput(session, "slider1", min = 0,max=100, value = 10)
}
})
}
runApp(list(ui = ui, server = server))
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.
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.
get previous objects before x object
how can I get say the previous 5 objects before x object when I know x's id?
For example I get the 5 last objects of a model like this
numPosts = Post.objects.filter(topic=topic).count()
pre = numPosts - 5
posts = Post.objects.filter(topic=topic).order_by('date')[pre:numPosts]
Now if I know the id of the post with the oldest date, how can I get the 5 next objects, or less if there are not enough?
http://docs.djangoproject.com/en/dev/topics/db/queries/#limiting-querysets
posts = Post.objects.filter(topic=topic).order_by('date')
x = posts.get(id=id)
next_five = posts.filter(date__lt=x.date)[:5]
should return the next 5 (or less) objects