Set the `edgecolor` to `&quot;none&quot;`: `bar(..., edgecolor = &quot;none&quot;)`

Another option is to set `edgecolor` to be the intended color in your call to `bar`:

    # If your intended color is blue, this will work:
    bar(. . . , edgecolor=&#39;b&#39;)

I am having trouble with a mysql query.  I want to exclude values of 2.  So I thought I would do following:

    table products

    id | name     | backorder
    -------------------
    1  | product1 | NULL
    2  | product2 | NULL
    3  | product3 | 2

    SELECT name from `products` p
    WHERE backorder &lt;&gt; &#39;2&#39;

However, This is not giving the desired result of product1, product 2  It is giving an empty results table.

On the other hand if I use 

    SELECT name from `products` p
    WHERE backorder = &#39;2&#39;

Then it produces: `product3`.  But I want to get those records where it is not equal to `2`.

Something is not working with the `&lt;&gt; &#39;2&#39;`.  Could it be that the `NULL` values are throwing it off?  Can anyone suggest a fix.

Thanks in advance!

MYSQL syntax not evaluating not equal to in presence of NULL

I saw in some frameworks this line of code:

    return new static($view, $data);


how do you understand the `new static`?



what means new static?

I&#39;m using pyplot.bar but I&#39;m plotting so many points that the color of the bars is always black.  This is because the borders of the bars are black and there are so many of them that they are all squished together so that all you see is the borders (black).  Is there a way to remove the bar borders so that I can see the intended color?

matplotlib bar graph black - how do I remove bar borders

<p>I'm using pyplot.bar but I'm plotting so many points that the color of the bars is always black.  This is because the borders of the bars are black and there are so many of them that they are all squished together so that all you see is the borders (black).  Is there a way to remove the bar borders so that I can see the intended color?</p>


I&#39;d like to create a `colorbar` legend for a `heatmap`, such that the labels are in the center of each discrete color. [Example borrowed from here][1]:

    import matplotlib.pyplot as plt
    import numpy as np
    from matplotlib.colors import ListedColormap

    #discrete color scheme
    cMap = ListedColormap([&#39;white&#39;, &#39;green&#39;, &#39;blue&#39;,&#39;red&#39;])

    #data
    np.random.seed(42)
    data = np.random.rand(4, 4)
    fig, ax = plt.subplots()
    heatmap = ax.pcolor(data, cmap=cMap)

    #legend
    cbar = plt.colorbar(heatmap)
    cbar.ax.set_yticklabels([&#39;0&#39;,&#39;1&#39;,&#39;2&#39;,&#39;&gt;3&#39;])
    cbar.set_label(&#39;# of contacts&#39;, rotation=270)

    # put the major ticks at the middle of each cell
    ax.set_xticks(np.arange(data.shape[1]) + 0.5, minor=False)
    ax.set_yticks(np.arange(data.shape[0]) + 0.5, minor=False)
    ax.invert_yaxis()

    #labels
    column_labels = list(&#39;ABCD&#39;)
    row_labels = list(&#39;WXYZ&#39;)
    ax.set_xticklabels(column_labels, minor=False)
    ax.set_yticklabels(row_labels, minor=False)

    plt.show()

This generates the following plot:

[![pmesh plot][2]][2]

Ideally I&#39;d like to generate a legend bar which has the four colors and for each color, a label in its center: `0,1,2,&gt;3`. How can this be achieved?

  [1]: https://stackoverflow.com/questions/14406214/moving-x-axis-to-the-top-of-a-plot-in-matplotlib
  [2]: http://i.stack.imgur.com/v07GA.png

matplotlib: colorbars and its text labels

I&#39;m trying to do this:

    h = [0.2, 0.2, 0.2, 0.2, 0.2]
    
    Y = np.convolve(Y, h, &quot;same&quot;)

`Y` looks like this:

![screenshot][1]


  [1]: http://i.stack.imgur.com/bVYmZ.jpg

While doing this I get this error:
```none
ValueError: object too deep for desired array
```
Why is this?

My guess is because somehow the `convolve` function does not see `Y` as a 1D array.

What does &quot;ValueError: object too deep for desired array&quot; mean and how to fix it?

Is there a way to select random rows from a DataFrame in Pandas.

In R, using the car package, there is a useful function `some(x, n)` which is similar to head but selects, in this example, 10 rows at random from x.

I have also looked at the slicing documentation and there seems to be nothing equivalent.

### Update
Now using version 20. There is a sample method.

```
df.sample(n)
```


Random row selection in Pandas dataframe

I know how to set the transparency of a line in matplotlib. For example, the following code makes the line and the markers transparent.

    import numpy as np
    import matplotlib.pyplot as plt

    vec = np.random.uniform(0, 10, 50)
    f = plt.figure(1)
    ax = f.add_subplot(111)
    ax.plot(vec, color=&#39;#999999&#39;, marker=&#39;s&#39;, alpha=0.5)

I want line&#39;s alpha=1.0, and marker&#39;s face color to be semi-transparent (alpha=0.5). Can this be done in matplotlib? 

Thank you.

Matplotlib - How to make the marker face color transparent without making the line transparent

I have to make a Lagrange polynomial in Python for a project I&#39;m doing. I&#39;m doing a barycentric style one to avoid using an explicit for-loop as opposed to a Newton&#39;s divided difference style one. The problem I have is that I need to catch a division by zero, but Python (or maybe numpy) just makes it a warning instead of a normal exception.

So, what I need to know how to do is to catch this warning as if it were an exception. The related questions to this I found on this site were answered not in the way I needed. Here&#39;s my code:

	import numpy as np
	import matplotlib.pyplot as plt
	import warnings

	class Lagrange:
		def __init__(self, xPts, yPts):
			self.xPts = np.array(xPts)
			self.yPts = np.array(yPts)
			self.degree = len(xPts)-1 
			self.weights = np.array([np.product([x_j - x_i for x_j in xPts if x_j != x_i]) for x_i in xPts])
		
		def __call__(self, x):
			warnings.filterwarnings(&quot;error&quot;)
			try:
				bigNumerator = np.product(x - self.xPts)
				numerators = np.array([bigNumerator/(x - x_j) for x_j in self.xPts])
				return sum(numerators/self.weights*self.yPts) 
			except Exception, e: # Catch division by 0. Only possible in &#39;numerators&#39; array
				return yPts[np.where(xPts == x)[0][0]]
			
	L = Lagrange([-1,0,1],[1,0,1]) # Creates quadratic poly L(x) = x^2

	L(1) # This should catch an error, then return 1. 

When this code is executed, the output I get is:

    Warning: divide by zero encountered in int_scalars

That&#39;s the warning I want to catch. It should occur inside the list comprehension.


How do I catch a numpy warning like it&#39;s an exception (not just for testing)?

What is the main difference between dynamic programming and greedy approach in terms of usage?

As far as I understood, the _greedy_ approach sometimes gives an optimal solution; in other cases, the _dynamic programming_ approach gives an optimal solution. 

Are there any particular conditions which must be met in order to use one approach (or the other) to obtain an optimal solution?

What is the difference between dynamic programming and greedy approach?

Can anybody please provide or point out to a good comparison between Neo4j and Titan? 
One thing i can see is in terms of scale - Titan is scaleout and requires an underlying scalable datastore like cassandra. Neo4j is only for HA and has its own embedded database. Any other pros and cons? Any specific usecases. (Is Titan being used anywhere currently?)
 
I also have the following link: http://architects.dzone.com/articles/16-graph-databases-compared that gives a objective compare for graph databases but not much on pros and cons between Neo4j and Titan.


anybody tried neo4j vs titan - pros and cons

I&#39;ve considered creating a Vertices table and an Edges table but would building graphs in memory and traversing sub-graphs require a large number of lookups? I&#39;d like to avoid excessive database reads. Is there any other way of persisting a graph? 

Side note: I&#39;ve heard of Neo4j but my question is really how to conceptually represent a graph in a standard database. I am open to some NoSQL solutions like mongodb though.

How to persist a graph data structure in a relational database?

Note that a graph is represented as an adjacency list.

I&#39;ve heard of 2 approaches to find a cycle in a graph:

1. Keep an array of boolean values to keep track of whether you visited a node before. If you run out of new nodes to go to (without hitting a node you have already been), then just backtrack and try a different branch.

1. The one from Cormen&#39;s CLRS or Skiena: For depth-first search in undirected graphs, there are two types of edges, tree and back. The graph has a cycle if and only if there exists a back edge.

Can somebody explain what are the back edges of a graph and what&#39;s the diffirence between the above 2 methods.

Thanks.

**Update:**
Here&#39;s the code to detect cycles in both cases. Graph is a simple class that represents all graph-nodes as unique numbers for simplicity, each node has its adjacent neighboring nodes (g.getAdjacentNodes(int)):

    public class Graph {
    
      private int[][] nodes; // all nodes; e.g. int[][] nodes = {{1,2,3}, {3,2,1,5,6}...};
    
      public int[] getAdjacentNodes(int v) {
        return nodes[v];
      }

      // number of vertices in a graph
      public int vSize() {
        return nodes.length;
      }

    }

**Java code to detect cycles in an undirected graph:**

        public class DFSCycle {
       
        private boolean marked[];
        private int s;
        private Graph g;
        private boolean hasCycle;
    
        // s - starting node
        public DFSCycle(Graph g, int s) {
            this.g = g;
            this.s = s;
            marked = new boolean[g.vSize()];
            findCycle(g,s,s);
        }
    
        public boolean hasCycle() {
            return hasCycle;
        }
    
        public void findCycle(Graph g, int v, int u) {
    
            marked[v] = true;
    
            for (int w : g.getAdjacentNodes(v)) {
                if(!marked[w]) {
                    marked[w] = true;
                    findCycle(g,w,v);
                } else if (v != u) {
                    hasCycle = true;
                    return;
                }
            }
    
        }  
    }

**Java code to detect cycles in a directed graph:**

    public class DFSDirectedCycle {
    
        private boolean marked[];
        private boolean onStack[];
        private int s;
        private Graph g;
        private boolean hasCycle;
    
        public DFSDirectedCycle(Graph g, int s) {
            this.s = s
            this.g = g;
            marked = new boolean[g.vSize()];
            onStack = new boolean[g.vSize()];
            findCycle(g,s);
        }
    
        public boolean hasCycle() {
            return hasCycle;
        }
    
        public void findCycle(Graph g, int v) {
    
            marked[v] = true;
            onStack[v] = true;
    
            for (int w : g.adjacentNodes(v)) {
                if(!marked[w]) {
                    findCycle(g,w);
                } else if (onStack[w]) {
                    hasCycle = true;
                    return;
                }
            }
    
            onStack[v] = false;
        }
    }

Detecting cycles in a graph using DFS: 2 different approaches and what&#39;s the difference

How can one neatly represent a [graph][1] in [Python][2]? (Starting from scratch i.e. no libraries!)&lt;br/&gt;What data structure (e.g. dicts/tuples/dict(tuples)) will be fast but also memory efficient?&lt;br/&gt;One must be able to do various graph [operations][3] on it.&lt;br/&gt;&lt;br/&gt;
As pointed out, the various [graph representations][4] might help. How does one go about implementing them in Python?&lt;br/&gt;&lt;br/&gt;As for the libraries, [this question][5] has quite good answers.


  [1]: https://en.wikipedia.org/wiki/Graph_%28data_structure%29
  [2]: https://en.wikipedia.org/wiki/Python_(programming_language)
  [3]: https://en.wikipedia.org/wiki/Graph_%28data_structure%29#Operations
  [4]: https://en.wikipedia.org/wiki/Graph_(abstract_data_type)#Representations
  [5]: https://stackoverflow.com/questions/606516/python-graph-library

Representing graphs (data structure) in Python

Suppose I have a for loop and I want to plot points in different colors:

    for i in range(5):
     plt.plot(x,y,col=i)

How do I automatically change colors in the for loop?

Plotting different colors in matplotlib

Is there any way to plot a bar plot using `matplotlib` using data directly from a dict? 

My dict looks like this: 

    D = {u&#39;Label1&#39;:26, u&#39;Label2&#39;: 17, u&#39;Label3&#39;:30}

I was expecting 

    fig = plt.figure(figsize=(5.5,3),dpi=300)
    ax = fig.add_subplot(111)
    bar = ax.bar(D,range(1,len(D)+1,1),0.5)

to work, but it does not. 

Here is the error:

    &gt;&gt;&gt; ax.bar(D,range(1,len(D)+1,1),0.5)
    Traceback (most recent call last):
      File &quot;&lt;stdin&gt;&quot;, line 1, in &lt;module&gt;
      File &quot;/usr/local/lib/python2.7/site-packages/matplotlib/axes.py&quot;, line 4904, in bar
        self.add_patch(r)
      File &quot;/usr/local/lib/python2.7/site-packages/matplotlib/axes.py&quot;, line 1570, in add_patch
        self._update_patch_limits(p)
      File &quot;/usr/local/lib/python2.7/site-packages/matplotlib/axes.py&quot;, line 1588, in _update_patch_limits
        xys = patch.get_patch_transform().transform(vertices)
      File &quot;/usr/local/lib/python2.7/site-packages/matplotlib/patches.py&quot;, line 580, in get_patch_transform
        self._update_patch_transform()
      File &quot;/usr/local/lib/python2.7/site-packages/matplotlib/patches.py&quot;, line 576, in _update_patch_transform
        bbox = transforms.Bbox.from_bounds(x, y, width, height)
      File &quot;/usr/local/lib/python2.7/site-packages/matplotlib/transforms.py&quot;, line 786, in from_bounds
        return Bbox.from_extents(x0, y0, x0 + width, y0 + height)
    TypeError: coercing to Unicode: need string or buffer, float found

Plot a bar using matplotlib using a dictionary

I don&#39;t understand what does comma after variable **lines,** means: http://matplotlib.org/examples/animation/simple_anim.html

    line, = ax.plot(x, np.sin(x))

If I remove comma and variable &quot;line,&quot; becomes variable &quot;line&quot; then program is broken. Full code from url given above:

    import numpy as np
    import matplotlib.pyplot as plt
    import matplotlib.animation as animation
    
    fig = plt.figure()
    ax = fig.add_subplot(111)
    
    x = np.arange(0, 2*np.pi, 0.01)        # x-array
    line, = ax.plot(x, np.sin(x))
    
    def animate(i):
        line.set_ydata(np.sin(x+i/10.0))  # update the data
        return line,
    
    #Init only required for blitting to give a clean slate.
    def init():
        line.set_ydata(np.ma.array(x, mask=True))
        return line,
    
    ani = animation.FuncAnimation(fig, animate, np.arange(1, 200), init_func=init,
        interval=25, blit=True)
    plt.show()

According to http://docs.python.org/3/tutorial/datastructures.html#tuples-and-sequences comma after variable seems to be related to tuples containing only one item.

x, = ... - is this trailing comma the comma operator?

I used: 
`setFixedSize(size());`
to stop the window from resizing, but the resize arrows still appear when the mouse is over the border of the window.

Is there a better way to disable window resizing to avoid showing the arrows when crossing the border?

how can I fully disable resizing a window including the resize icon when the mouse hovers the border?

I want to remove the stylings from a textarea and leave it all white without any border or glow, if possible. I&#39;ve tried with different stuff found here on SO, but nothing works (tried with FF and Chrome).

So, is it possible and if so how to do it?

![enter image description here][1]


  [1]: http://i.stack.imgur.com/ekC5J.png

**What I&#39;ve tried so far:**

&lt;!-- language: lang-css --&gt;

    textarea#story {
      // other stuff
      -moz-appearance:none;
      outline:0px none transparent;
    }
    
    textarea:focus, input:focus{
        outline: 0;
    }
    
    *:focus {
        outline: 0;
    }

Remove all stylings (border, glow) from textarea

My question is on the title.

I don&#39;t know how to add a border in a specific side, top or bottom, any side...
`layer.border` draws the border for the whole view...



How to add a border just on the top side of a UIView

With Photoshop, I can put two different border to an element with two different color. And with that, I can make many dynamic shade-effect with my elements. Even with Photoshop effects, I can manage that with Drop Shadow and Inner Shadow.

On the Web Design concern, if I have design like the image below, how can I achieve that with CSS? Is it really possible?&lt;br/&gt;
![border with different color][1]

**NOTE:** I&#39;m giving two borders to the white element: the outer border is white, and the inner border is greyish. Together, they create a dynamic look so that it feels like an inset element, and the white element is pillow embossed. So thing is a bit:

    div.white{
       border: 2px solid white;
       border: 1px solid grey;
    }

But you know it&#39;s a double declaration, and is invalid. So how can I manage such thing in CSS?

And if I put `border-style: double` then you know I can&#39;t pass two different color for the singe `double` border.

    div.white{
           border: double white grey;
    }

Additionally, I&#39;m familiar with LESS CSS Preprocessor. So if such a thing is possible using CSS Preprocessor, please let me know.


  [1]: http://i.stack.imgur.com/vtvIz.jpg

Double border with different color

When using ggplot, I can set `shape` to 21-25 to get shapes that have independent setting for the internal (`fill`) and border (`col`) colors, like so:

    df &lt;- data.frame(id=runif(12), x=1:12, y=runif(12))
    ggplot(df, aes(x=x, y=y)) + 
      geom_point(aes(fill=id, size=id), colour=&quot;black&quot;, shape=21)

![enter image description here][1]

However, I can&#39;t figure out how to control the thickness of the shape borders, either setting them absolutely or as an aesthetic mapping.  I note that if I set an `lwd` value, it overrides the `size` aesthetic:

    ggplot(df, aes(x=x, y=y)) + 
      geom_point(aes(fill=id, size=id), colour=&quot;black&quot;, shape=21, lwd=2)

![enter image description here][2]


How do I control the border thickness?

  [1]: http://i.stack.imgur.com/9eVZa.png
  [2]: http://i.stack.imgur.com/ogboS.png

Content Type	Original Author	Original Content on Stackoverflow
Question	user1893354	View Question on Stackoverflow
Solution 1 - Python	Robbert	View Answer on Stackoverflow
Solution 2 - Python	dbliss	View Answer on Stackoverflow

matplotlib bar graph black - how do I remove bar borders

Python Problem Overview

Python Solutions

Solution 1 - Python

Solution 2 - Python

what means new static?

MYSQL syntax not evaluating not equal to in presence of NULL

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