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I want to get both horizontal and vertical grid lines on my plot but only the horizontal grid lines are appearing by default. I am using a pandas.DataFrame from an sql query in python to generate a line plot with dates on the x-axis. I'm not sure why they do not appear on the dates and I have tried to search for an answer to this but couldn't find one.

All I have used to plot the graph is the simple code below. 

data.plot()
grid('on')

data is the DataFrame which contains the dates and the data from the sql query.

I have also tried adding the code below but I still get the same output with no vertical grid lines.

ax = plt.axes()        
ax.yaxis.grid() # horizontal lines
ax.xaxis.grid() # vertical lines

Any suggestions?

enter image description here

Velimir Mlaker
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Osmond Bishop
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7 Answers7

121

You may need to give boolean arg in your calls, e.g. use ax.yaxis.grid(True) instead of ax.yaxis.grid(). Additionally, since you are using both of them you can combine into ax.grid, which works on both, rather than doing it once for each dimension.

ax = plt.gca()
ax.grid(True)

That should sort you out.

wim
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    I tried it but for some reason it still looks the same as before – Osmond Bishop Apr 18 '13 at 04:21
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    Are you doing this in interactive interpreter? Make sure you're setting the grid _before_ calling `plt.show()` – wim Apr 18 '13 at 04:25
  • I am using iPython. I have tried adding plt.show() it won't make a difference. – Osmond Bishop Apr 18 '13 at 04:32
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    Well this is odd. What's your ipython version, also try running it like `ipython --pylab`, and do `plt.grid(True)` immediately - do you see the grid? – wim Apr 18 '13 at 05:09
  • I tried `plt.grid(True)` and got the empty graph with both the vertical and horizontal grid lines, so yes it is odd why I can't get this for my line plot. I am running the latest available version of iPython. – Osmond Bishop Apr 18 '13 at 23:28
  • Maybe there's one grid in 00:00 and no grid in others. I meet the same problem that only one grid in Nov 1 while no grid in other days. – Lory_yang Nov 16 '16 at 03:00
  • Just plt.grid(True) will work. – Paul Kenjora Dec 30 '21 at 01:40
69

plt.gca().xaxis.grid(True) proved to be the solution for me

isedev
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matt
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    The `myaxes.grid(which='x')` wasn't working for me with matplotlib version 1.4.2... couldn't get the `which` keyword to work at all. However, `myaxes.xaxis.grid(True)` did the trick and is conceptually better IMO. Oh, and don't forget about the useful `myaxes.set_axisbelow(True)` method to put the grid behind the data. – travc Nov 16 '14 at 19:26
35

According to matplotlib documentation, The signature of the Axes class grid() method is as follows:

Axes.grid(b=None, which='major', axis='both', **kwargs)
Turn the axes grids on or off.

which can be ‘major’ (default), ‘minor’, or ‘both’ to control whether major tick grids, minor tick grids, or both are affected.

axis can be ‘both’ (default), ‘x’, or ‘y’ to control which set of gridlines are drawn.

So in order to show grid lines for both the x axis and y axis, we can use the the following code:

ax = plt.gca()
ax.grid(which='major', axis='both', linestyle='--')

This method gives us finer control over what to show for grid lines.

jdhao
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14

Short answer (read below for more info):

ax.grid(axis='both', which='both')

enter image description here

What you do is correct and it should work.

However, since the X axis in your example is a DateTime axis the Major tick-marks (most probably) are appearing only at the both ends of the X axis. The other visible tick-marks are Minor tick-marks.

The ax.grid() method, by default, draws grid lines on Major tick-marks. Therefore, nothing appears in your plot.

Use the code below to highlight the tick-marks. Majors will be Blue while Minors are Red.

ax.tick_params(which='both', width=3)
ax.tick_params(which='major', length=20, color='b')
ax.tick_params(which='minor', length=10, color='r')

Now to force the grid lines to be appear also on the Minor tick-marks, pass the which='minor' to the method:

ax.grid(b=True, which='minor', axis='x', color='#000000', linestyle='--')

or simply use which='both' to draw both Major and Minor grid lines. And this a more elegant grid line:

ax.grid(b=True, which='minor', axis='both', color='#888888', linestyle='--')
ax.grid(b=True, which='major', axis='both', color='#000000', linestyle='-')
Dark
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8

maybe this can solve the problem: matplotlib, define size of a grid on a plot

ax.grid(True, which='both')

The truth is that the grid is working, but there's only one v-grid in 00:00 and no grid in others. I meet the same problem that there's only one grid in Nov 1 among many days.

Community
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Lory_yang
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4

For only horizontal lines

ax = plt.axes()        
ax.yaxis.grid() # horizontal lines

This worked

barbsan
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Mudit
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0

Try:

plt.grid(True)

This turns on both horizontal and vertical grids for date series with major tick marks in the right place.

Using Python3 / MatPlotLib 3.4.3

Paul Kenjora
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