I was looking at how the wrap decorator was implemented in functools.py and it used partial(), which I then wanted to see how that was implemented.  It was imported from _functools so I looked for _functools.py but couldn't find it.  I grepped the whole python directory, and then my entire C: drive but nothing came up.  Where is this file located? (Win7 x64)
How do I learn where the source file for a given Python module is installed? Is the method different on Windows than on Linux?  I'm trying to look for the source of the datetime module in particular, but I'm interested in a more general answer as well.
Should the mean be used when data are skewed? Often introductory applied statistics texts distinguish the mean from the median (often in the the context of descriptive statistics and motivating the summarization of central tendency using the mean, median and mode) by explaining that the mean is sensitive to outliers in sample data and/or to skewed population distributions, and this is used as a justification for an assertion that the median is to be preferred when the data are not symmetrical.  For example:     The best measure of central tendency for a given set of data often depends on the way in which the values are distributed.... When data are not symmetric, the median is often the best measure of central tendency. Because the mean is sensitive to extreme observations, it is pulled in the direction of the outlying data values, and as a result might end up excessively inflated or excessively deflated."   —Pagano and Gauvreau, (2000) Principles of Biostatistics, 2nd ed. (P&amp;G were at hand, BTW, not singling them out per se.)   The authors define "central tendency" thus: "The most commonly investigated characteristic of a set of data is its center, or the point about which observations tend to cluster."  This strikes me as a less-than forthright way of saying only use the median, period, because only using the mean when the data/distributions are symmetrical is the same thing as saying only use the mean when it equals the median. Edit: whuber rightly points out that I am conflating robust measures of central tendency with the median. So it is important to keep in mind that I am discussing the specific framing of the arithmetic mean versus the median in introductory applied statistics (where, mode aside, other measures of central tendency are not motivated).  Rather than judging the utility of the mean by how much it departs from the behavior of the median, ought we not simply understand these as two different measures of centrality? In other words being sensitive to skewness is a feature of the mean. One could just as validly argue "well the median is no good because it is largely insensitive to skewness, so only use it when it equals the mean."  (The mode is quite sensibly not getting involved with this question.) How to create this curved shadow in Photoshop? How to create the shadow effect like the URL/image below? Specifically, the rounded/curved shadow at the bottom: Subsurf modifier rounding sharp edges I tried to apply a Subdivision Surface on a part of my object. I can't keep the angles sharp, they all turn into rounded angles.  The angle before applying the Subdivision surface...   ...And after Configuring Firefox to use a proxy from the command line I'm looking for a way to tell Firefox to use a proxy in Ubuntu Ludid (10.04.1 LTS).   I'm installing Ubuntu semi-automatically on several identical machines. For this, I use a script that, amongst other things, sets system-wide proxy settings:  echo "export http_proxy=http://myproxy:3128/" &gt; /etc/profile.d/proxy.sh echo "export HTTP_PROXY=http://myproxy:3128/" &gt;&gt; /etc/profile.d/proxy.sh chmod a+x /etc/profile.d/proxy.sh   I can confirm that the variables are set correctly when checking in a shell. Most programs respect this setting and use my proxy. Firefox, however, does not. When I open its network connection settings dialog, however, it is pre-set to "use system settings" for the proxy.   What does Firefox expect here? A differently-named variable? Can I set something in FF's prefs.js? Why do we need sigma-algebras to define probability spaces? We have a random experiment with different outcomes forming the sample space $\Omega,$ on which we look with interest at certain patterns, called events $\mathscr{F}.$ Sigma-algebras (or sigma-fields) are made up of events to which a probability measure $\mathbb{P}$ can be assigned. Certain properties are fulfilled, including the inclusion of the null set $\varnothing$ and the entire sample space, and an algebra that describes unions and intersections with Venn diagrams.  Probability is defined as a function between the $\sigma$-algebra and the interval $[0,1]$.  Altogether, the triple $(\Omega, \mathscr{F}, \mathbb{P})$ forms a probability space.  Could someone explain in plain English why the probability edifice would collapse if we didn't have a $\sigma$-algebra? They are just wedged in the middle with that impossibly calligraphic "F". I trust they are necessary; I see that an event is different from an outcome, but what would go awry without a $\sigma$-algebras?     The question is: In what type of probability problems the definition of a probability space including a $\sigma$-algebra becomes a necessity?       provides a plain English accessible explanation. The idea is a spinning pointer rotating counterclockwise on a circle of unit perimeter:       We begin by constructing a spinner, which consists of a circle of unit   circumference and a pointer as shown in [the] Figure. We pick a point   on the circle and label it $0$, and then label every other point on the   circle with the distance, say $x$, from $0$ to that point, measured   counterclockwise. The  experiment  consists  of spinning the pointer and    recording the label of the point at the tip of the pointer. We let the random   variable $X$ denote the value of this outcome.  The sample space is   clearly the interval $[0,1)$.  We would like to construct a   probability model in which each outcome is equally likely to occur. If   we proceed as we did [...] for experiments with a finite number of   possible outcomes,  then we must assign the probability $0$ to each   outcome,  since otherwise,  the  sum  of  the  probabilities,  over    all  of  the  possible  outcomes,  would not equal 1.  (In fact,   summing an uncountable number of real numbers is a tricky business;    in  particular,  in  order  for  such  a  sum  to  have  any  meaning,   at  most countably many of the summands can be different than $0$.)    However, if all of the assigned probabilities are $0$, then the sum is   $0$, not $1$, as it should be.   So if we assigned to each point any probability, and given that there is an (uncountably) infinity number of points, their sum would add up to $&gt; 1$. Lots of ram. How to use it? My PC has 8 Gb of ram. Is there any way to make ubuntu use most of it? I mean rarely drop caches and keep once opened programms in ram longer, preload apps on boot, etc. Masking NetCDF time series data from shapefile using Python I have a 3-D time-series precipitation data (187 x 1800 x 3600), stored in a NetCDF file. I need to obtain the precipitation data for a shapefile. import matplotlib.pyplot as plt from netCDF4 import Dataset, num2date,  from matplotlib.pyplot import figure from datetime import datetime, date, timedelta import numpy as np import xarray as xr import pandas as pd import geopandas as gpd       MSWEP_monthly = 'D:\G3P\DATA\Models\MSWEP\MSWEP_monthly.nc4'  MSWEP_monthly = Dataset(MSWEP_monthly, 'r') Pre_MSWEP = MSWEP_monthly.variables['precipitation'][:]   MSWEP_monthly2 = xr.open_dataarray('D:\G3P\DATA\Models\MSWEP\MSWEP_monthly.nc4')  Lon_MSWEP = MSWEP_monthly2.lon Lat_MSWEP = MSWEP_monthly2.lat  Africa_Shape = gpd.read_file('D:\G3P\DATA\Shapefile\Africa_SHP\Africa.shp')    from osgeo import gdal,osr,ogr  def makeMask(lon,lat,res):     source_ds = ogr.Open(shapefile)     source_layer = source_ds.GetLayer()       # Create high res raster in memory     mem_ds = gdal.GetDriverByName('MEM').Create('', lon.size, lat.size, gdal.GDT_Byte)     mem_ds.SetGeoTransform((lon.min(), res, 0, lat.max(), 0, -res))     band = mem_ds.GetRasterBand(1)       # Rasterize shapefile to grid     gdal.RasterizeLayer(mem_ds, [1], source_layer, burn_values=[1])       # Get rasterized shapefile as numpy array     array = band.ReadAsArray()        mem_ds = None     band = None     return array  shapefile = 'D:\G3P\DATA\Shapefile\Africa_SHP\Africa.shp' source_ds = ogr.Open(shapefile)  # calculate the cellsize cellsize = Lon_MSWEP[:][1] - Lon_MSWEP[:][0]   # create the mask mask = makeMask(Lon_MSWEP,Lat_MSWEP,cellsize)  Now if I implement the following code, the precipitation data for the first day (from the time-series) can be obtained with shape of 1800x3600: precip = np.ma.masked_where(mask==0,Pre_MSWEP[0,:,:])  I tried to use a for loop to mask the precipitation data for the entire time series (time, lon, lat) over the area of interest. however, the below code gives me a 2-D data, probably for the last day. Why is that? for i in range(len(Pre_MSWEP)):     precip = np.ma.masked_where(mask==0,Pre_MSWEP[i,:,:]) Scheduling a Batch job at a particular time I have a Apex batch class which I would like to schedule at a particular date time. The date time is stored in a variable and changes dynamically. ex Datatime scduleDateTime = datetime.now() ; I want to schedule the apex batch file to run at this datetime variable value.  How can I do that using system.scheduleBatch()  I started with this but could'nt see how I can specify a datetime variable in here:  datetime d = datetime.now(); sampleapexbatch b = new sampleapexbatch(d); System.scheduleBatch(b,'Sample Job',XXXXXXXX)   Any help is appreciated! How do i prove that $(p \vee q) \wedge (\neg p \vee r) \rightarrow (q \vee r)$ is a tautology without using the truth table? Counting in a rectangular grid with obstacles I was asked to find the no. of ways to get from (0,0) to (8,8) with the 4 points of the shaded box unpassable, aka I can't use the 4 points namely (3,3)(4,4)(3,4)(4,3) while on my way to (8,8). Right and up movements.  I know it is something like a pascal triangle and worked out the solution of 4050 ways.  May I know if there are any faster means using permutation formula?  Thank you in advance. I need to periodically run a command that ensures that some text files are kept in Linux mode. Unfortunately dos2unix always modifies the file, which would mess file's and folder's timestamps and cause unnecessary writes.   The script I write is in Bash, so  I'd prefer answers based on Bash. How do I recover lost/inaccessible data from my storage device? What steps can I take to try to recover lost or inaccessible data from any storage device?  Answers:   This applies to any computer storage device, e.g. internal/external hard drives, USB sticks, flash memory. The most important thing is to STOP using it, any type of I/O can ruin your chances of a recovery.     We have separate questions covering common problems with USB flash drives in greater detail: Was Hogwarts named such because of a connection to warthogs? Was Hogwarts named 'Hogwarts' because of a connection to warthogs?  Or was it named for hogs and warts separately, or something else entirely? I have seen people apply a filter to imported data before plotting with pgfplots, see . Is there a way to extend the approach presented there to apply multiple filters? In the MWE below I made the naive modifications to the solution given there, but it seems that only the last filter is applied: the unwanted y=1 data points are plotted too.  \documentclass{article} \usepackage{filecontents} \usepackage{pgfplots}  \begin{filecontents}{foo.txt}   x y z f   0 0 0 0   0 0 1 1   0 1 0 2   0 1 1 3   1 0 0 4   1 0 1 5   1 1 0 6   1 1 1 7   \end{filecontents}  \pgfplotsset{   discard if not/.style 2 args={   x filter/.code={   \edef\tempa{\thisrow{#1}}   \edef\tempb{#2}   \ifx\tempa\tempb   \else     \def\pgfmathresult{nan}   \fi   }}   }  \begin{document} \begin{figure}   \centering   \begin{tikzpicture}   \begin{axis}   \addplot table[x=x, y=f,                  discard if not={y}{0},                  discard if not={z}{0},                 ] {foo.txt};   \end{axis}   \end{tikzpicture}   \caption{$f(x)$ given $y=0$ and $z=0$.}   \end{figure} \end{document} Is it possible to have a rate of change of acceleration? I know this may seem a weird question, but it always bothers me. My physics book (Resnick,Halliday,Walker), and also various sites never say anything beyond acceleration.   But when a moving body is being acted by a variable force , its acceleration will definitely change: it will either increase or decrease. Then there will be rate of change of acceleration with respect to time. So, why don't books mention this? What is the cause for not measuring $\frac{d\vec{a}}{dt}$ ? If it exists, what is the use of it? Numbering side-by-side equations or inline equations Help with completing the proof: Any unbounded sequence is either infinitely large or has a convergent subsequential limit Given $\{x_n\}$ is an unbounded sequence, prove:   $$ \lim_{n\to\infty}x_n = \infty\ \  \text{or}\ \ \lim_{n_k \to \infty} = A $$   In other words any unbounded sequence either infinitely large or has a convergent subsequence.     Everything before udpate section is wrong.  Part 1. Proving $|x_n| &gt; M \implies \lim_{n\to\infty} x_n = \infty$  $\Box$ Start with the definition of an unbounded sequence: $$ \forall M &gt; 0 \in \Bbb R \ \exists N \in \Bbb N: \forall n &gt; N\implies |x_n| &gt; M $$  Suppose that: $$ \lim_{n\to\infty}x_n \ne \infty $$ That means: $$ \forall n\in\Bbb N\ \exists C &gt;0 \in\Bbb R : |x_n| &lt; C $$  Now taking $M^\prime = \max\{M, C\}$ we have that: $$ \begin{cases} \begin{align} \exists N \in \Bbb N : &amp;\forall n&gt;N \implies &amp;|x_n| &gt; M^\prime \\ &amp;\forall n \in \Bbb N: &amp;|x_n| &lt; M^\prime \end{align} \end{cases} $$  So we have arrived to a contradiction which means the assumption is wrong and: $$ \lim_{n\to\infty}x_n = \infty $$ $\Box$     Part 2. It's not clear to me how to prove that if unboundedness does not imply infinity limit then it must imply the existence of a convergent subsequence.   Two questions is my mind:   Is part 1 correct?  How do I proceed with the second part?     I'm using the following definition. $$ \lim_{n\to\infty}x_n = +\infty \stackrel{\text{def}}{\iff} \forall \epsilon &gt; 0 \exists N \in \Bbb N :\forall n &gt; N \implies x_n &gt; \epsilon \\ \lim_{n\to\infty}x_n = -\infty \stackrel{\text{def}}{\iff} \forall \epsilon &gt; 0 \exists N \in \Bbb N :\forall n &gt; N \implies x_n &lt; -\epsilon \\ $$ A sequence is considered infinitely large when: $$ \lim_{n\to\infty}x_n = \infty\ \ \text{when}\ \ \lim_{n\to\infty}x_n = + \infty \ \ \text{or} \ \ \lim_{n\to\infty}x_n = - \infty $$    Update.   Looks like i've messed up a lot of things. I will try once again. As shown in comments and answers the statement holds only in case: $$ \lim_{n\to\infty} |x_n| = \infty \iff \forall \epsilon &gt; 0 \exists N \in \Bbb N: \forall n &gt; N \implies |x_n| &gt; \epsilon $$  Consider the following: $$ \lnot P = \lnot\left(\lim_{n\to\infty}|x_n| = \infty \right) \iff \exists \epsilon &gt; 0\ \forall N_1 \in \Bbb N : \exists n &gt; N_1 \land |x_n| &lt; \epsilon $$  But on the other hand it is given that $x_n$ is unbounded: $$ Q = \forall M &gt; 0\ \exists N_2 \in \Bbb N : |x_{N_2}| &gt; M $$  Construct a negative expression for boundedness: $$ \lnot P = \exists M &gt; 0\ \forall N_2 \in \Bbb N : |x_{N_2}| &lt; M $$  If $S = \lnot P \implies \lnot Q$ then $S = P \lor \lnot Q$  Let $\epsilon = M$, choose $N = \max\{N_1, N_2\}$ then both statements are true and: $$ \exists \epsilon &gt; 0\ \forall N = \max\{N_1, N_2\}: \exists n &gt; N \land |x_n| &lt; \epsilon $$  Now either $P$ is true, which would mean $\lim |x_n| = \infty$, or $\lnot Q$ is true which would mean the sequence is bounded and hence contains a convergent subsequence. How to get the insert ID in JDBC? Are commands complete sentences? seems to indirectly ask the question, but the upvoted answer says &quot;the actual sentence is...&quot;. So my question is this: Are commands considered to be grammatically sound, complete sentences in the English language? Some examples:  Go. Add a note. Do work. How can I learn the basics of SharePoint 2013 in a few days? I have very little knowledge of SharePoint, and want to learn about SharePoint 2013.  Most of the resources that I've found are either about what's new in 2013, or they have a bunch of links to SharePoint 2010.  I also don't have the time to read a thousand page book.  A hundred or so would be fine.  Can anyone recommend a resource (site / book / video / tutorial) for a beginner to learn the basics of SharePoint 2013 in a few days?  I've downloaded a Kindle book, "Getting Started With SharePoint 2013."  It's perfect for absolute beginners, who just want to know how to upload &amp; download documents, but I'm looking for more than that.