how to override the solver function in sympy?
how to override the solver function in sympy? -- https://mail.python.org/mailman/listinfo/python-list
[RELEASE] Python 2.7.13 release candidate 1
It is my pleasure to announce the first release candidate of Python 2.7.13, a new bugfix release in the Python 2.7x series. Downloads may be found on python.org: https://www.python.org/downloads/release/python-2713rc1/ Please test the release and report any bugs to https://bugs.python.org A final release is scheduled for 2 weeks time. Servus, Benjamin (on behalf of all of 2.7's contributors) -- https://mail.python.org/mailman/listinfo/python-list
Re: What meaning is "if k in [0, len(n_trials) - 1] else None"?
On Sun, Dec 4, 2016 at 11:10 AM, Terry Reedy wrote: >> But the expression result isn't even used. So this is better written: > > > matplotlib.pyplot.xlabel sets x-axis scaling, with no documented return > value. > http://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.xlabel > If, as seems reasonable to assume, it returns None, the value of the > expression is 'None if x else None', which is to say, None. Hardly matters what the return value is, given that the code ignores it. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: What meaning is "if k in [0, len(n_trials) - 1] else None"?
On 12/3/2016 6:27 PM, Chris Angelico wrote:
On Sun, Dec 4, 2016 at 10:11 AM, Robert wrote:
I just notice that there is a slash character (\) before the if line.
What is it for?
Yes, that's important. The entire line of code is:
plt.xlabel("$p$, probability of heads") \
if k in [0, len(n_trials) - 1] else None
The backslash means "this continues on the next line".
> The ternary conditional looks like this:
5 if 1 < 2 else 7
Since 1 < 2, this has the value of 5. If not, it would have the value 7.
But the expression result isn't even used. So this is better written:
matplotlib.pyplot.xlabel sets x-axis scaling, with no documented return
value.
http://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.xlabel
If, as seems reasonable to assume, it returns None, the value of the
expression is 'None if x else None', which is to say, None.
if k in [0, len(n_trials) - 1]:
plt.xlabel("$p$, probability of heads")
--
Terry Jan Reedy
--
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Re: What meaning is "if k in [0, len(n_trials) - 1] else None"?
On 2016-12-03 23:11, Robert wrote:
On Saturday, December 3, 2016 at 6:09:02 PM UTC-5, Robert wrote:
Hi,
I am trying to understand the meaning of the below code snippet. Though I have
a Python IDLE at computer, I can't get a way to know below line:
if k in [0, len(n_trials) - 1] else None
I feel it is strange for what returns when the 'if' condition is true?
The second part 'None' is clear to me though.
Could you explain it to me?
thanks,
%matplotlib inline
from IPython.core.pylabtools import figsize
import numpy as np
from matplotlib import pyplot as plt
figsize(11, 9)
import scipy.stats as stats
dist = stats.beta
n_trials = [0, 1, 2, 3, 4, 5, 8, 15, 50, 500]
data = stats.bernoulli.rvs(0.5, size=n_trials[-1])
x = np.linspace(0, 1, 100)
# For the already prepared, I'm using Binomial's conj. prior.
for k, N in enumerate(n_trials):
sx = plt.subplot(len(n_trials) / 2, 2, k + 1)
plt.xlabel("$p$, probability of heads") \
if k in [0, len(n_trials) - 1] else None
plt.setp(sx.get_yticklabels(), visible=False)
heads = data[:N].sum()
y = dist.pdf(x, 1 + heads, 1 + N - heads)
plt.plot(x, y, label="observe %d tosses,\n %d heads" % (N, heads))
plt.fill_between(x, 0, y, color="#348ABD", alpha=0.4)
plt.vlines(0.5, 0, 4, color="k", linestyles="--", lw=1)
leg = plt.legend()
leg.get_frame().set_alpha(0.4)
plt.autoscale(tight=True
I just notice that there is a slash character (\) before the if line.
What is it for?
I've learn Python for a while, but I don't use it for more than 2 years now.
Thanks.
The backslash at the end of the line indicates that that the statement
continues onto the next line, so it's the same as:
plt.xlabel("$p$, probability of heads") if k in [0, len(n_trials) -
1] else None
However, that line is weird!
In Python there's a "ternary operator". The docs say:
"""The expression x if C else y first evaluates the condition, C rather
than x. If C is true, x is evaluated and its value is returned;
otherwise, y is evaluated and its value is returned."""
Suppose you have the expression:
"even" if x % 2 == 0 else "odd"
If x is a multiple of 2, that expression will evaluate to "even", else
it will evaluate to "odd".
The line in your code is misusing it as a statement. Normally you would
write this instead:
if k in [0, len(n_trials) - 1]:
plt.xlabel("$p$, probability of heads")
Why was it written that way? I have no idea, it's just weird...
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Re: What meaning is "if k in [0, len(n_trials) - 1] else None"?
On Sun, Dec 4, 2016 at 10:11 AM, Robert wrote:
> I just notice that there is a slash character (\) before the if line.
> What is it for?
Yes, that's important. The entire line of code is:
plt.xlabel("$p$, probability of heads") \
if k in [0, len(n_trials) - 1] else None
The backslash means "this continues on the next line". The ternary
conditional looks like this:
5 if 1 < 2 else 7
Since 1 < 2, this has the value of 5. If not, it would have the value 7.
But the expression result isn't even used. So this is better written:
if k in [0, len(n_trials) - 1]:
plt.xlabel("$p$, probability of heads")
ChrisA
--
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Re: What meaning is "if k in [0, len(n_trials) - 1] else None"?
On Saturday, December 3, 2016 at 6:09:02 PM UTC-5, Robert wrote:
> Hi,
>
> I am trying to understand the meaning of the below code snippet. Though I have
> a Python IDLE at computer, I can't get a way to know below line:
>
> if k in [0, len(n_trials) - 1] else None
>
> I feel it is strange for what returns when the 'if' condition is true?
> The second part 'None' is clear to me though.
>
> Could you explain it to me?
>
>
> thanks,
>
>
>
>
>
>
>
> %matplotlib inline
> from IPython.core.pylabtools import figsize
> import numpy as np
> from matplotlib import pyplot as plt
> figsize(11, 9)
>
> import scipy.stats as stats
>
> dist = stats.beta
> n_trials = [0, 1, 2, 3, 4, 5, 8, 15, 50, 500]
> data = stats.bernoulli.rvs(0.5, size=n_trials[-1])
> x = np.linspace(0, 1, 100)
>
> # For the already prepared, I'm using Binomial's conj. prior.
> for k, N in enumerate(n_trials):
> sx = plt.subplot(len(n_trials) / 2, 2, k + 1)
> plt.xlabel("$p$, probability of heads") \
> if k in [0, len(n_trials) - 1] else None
> plt.setp(sx.get_yticklabels(), visible=False)
> heads = data[:N].sum()
> y = dist.pdf(x, 1 + heads, 1 + N - heads)
> plt.plot(x, y, label="observe %d tosses,\n %d heads" % (N, heads))
> plt.fill_between(x, 0, y, color="#348ABD", alpha=0.4)
> plt.vlines(0.5, 0, 4, color="k", linestyles="--", lw=1)
>
> leg = plt.legend()
> leg.get_frame().set_alpha(0.4)
> plt.autoscale(tight=True
I just notice that there is a slash character (\) before the if line.
What is it for?
I've learn Python for a while, but I don't use it for more than 2 years now.
Thanks.
--
https://mail.python.org/mailman/listinfo/python-list
What meaning is "if k in [0, len(n_trials) - 1] else None"?
Hi,
I am trying to understand the meaning of the below code snippet. Though I have
a Python IDLE at computer, I can't get a way to know below line:
if k in [0, len(n_trials) - 1] else None
I feel it is strange for what returns when the 'if' condition is true?
The second part 'None' is clear to me though.
Could you explain it to me?
thanks,
%matplotlib inline
from IPython.core.pylabtools import figsize
import numpy as np
from matplotlib import pyplot as plt
figsize(11, 9)
import scipy.stats as stats
dist = stats.beta
n_trials = [0, 1, 2, 3, 4, 5, 8, 15, 50, 500]
data = stats.bernoulli.rvs(0.5, size=n_trials[-1])
x = np.linspace(0, 1, 100)
# For the already prepared, I'm using Binomial's conj. prior.
for k, N in enumerate(n_trials):
sx = plt.subplot(len(n_trials) / 2, 2, k + 1)
plt.xlabel("$p$, probability of heads") \
if k in [0, len(n_trials) - 1] else None
plt.setp(sx.get_yticklabels(), visible=False)
heads = data[:N].sum()
y = dist.pdf(x, 1 + heads, 1 + N - heads)
plt.plot(x, y, label="observe %d tosses,\n %d heads" % (N, heads))
plt.fill_between(x, 0, y, color="#348ABD", alpha=0.4)
plt.vlines(0.5, 0, 4, color="k", linestyles="--", lw=1)
leg = plt.legend()
leg.get_frame().set_alpha(0.4)
plt.autoscale(tight=True
--
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Re: How to properly retrieve data using requests + bs4 from multiple pages in a site?
On Thu, Dec 1, 2016 at 10:07 PM, Juan C. wrote: > It works, but it has a big issue: it gets all data from all units/courses/assignments at the same time, and this isn't very useful as I don't care about data from units from 1-2 years ago. How can I change the logic so it just gets the data I need at a given moment? For example, I may need to dump data for an entire unit, or just one course, or maybe even just one assignment. How can I achieve this behavior? Another "issue", I feel like handing my 'session' that I instantiated at user.py to program, then unit, then course and then assignment is a poor design, how can I make it better? > > Any other suggestions are welcome. Oh, forgot to tell, I'm using Python 3.5.2 x64. -- https://mail.python.org/mailman/listinfo/python-list
Re: Request Help With Byte/String Problem
On Fri, 02 Dec 2016 19:39:39 +, Grant Edwards wrote: > On 2016-12-02, Wildman via Python-list wrote: >> On Fri, 02 Dec 2016 15:11:18 +, Grant Edwards wrote: >> >>> I don't know what the "addr" array contains, but if addr is a byte >>> string, then the "int()" call is not needed, in Pythong 3, a byte is >>> already an integer: >>> >>> def format_ip(a): >>>return '.'.join(str(b) for b in a) >>> >>> addr = b'\x12\x34\x56\x78' >>> >>> print(format_ip(addr)) >> >> It is a byte string just like your 'addr =' example and >> the above code works perfectly. > > More importantly, you've now learned about generator comprehensions > (aka generator expressions) and the string type's "join" method. ;) I have seen the join method before but because of my lack of experience it didn't occur to me to use it. I bet I will remember it from now on. I stuck a few code examples into my 'snips' directory. Generator expressions are new to me. I have seen it's use but I didn't understand what it was and what it was doing, until now. Thanks again. -- GNU/Linux user #557453 The cow died so I don't need your bull! -- https://mail.python.org/mailman/listinfo/python-list
