We Keep Coding

How to plot and save with an <AxesSubplot:> output

I am using this function
It return one AxesSubplot:
I would like to save the plot that is ploted when show_plot=True as a png without changing the function.
How should I proceed ?
Best regards !

To get the whole figure, you could try:
ax.get_figure().savefig('fig_name.png')
If you have a figure with multiple subplots and you want to only extract one (ax):
# Get the bounding box of the subplot and expand it to include the axis labels and ticks.
# You will have to play with the expanded parameters.
subplot_box = ax.get_window_extent().transformed(ax.get_figure().dpi_scale_trans.inverted()).expanded(1.2, 1.4)
ax.get_figure().savefig('subplot.png', bbox_inches=extent)

Creating a graph that uses steps to connect dots using matplotlib?

I'm creating a plot using these lines of code, pretty standard.
plt.plot(x, It)
plt.plot(x, NIt, dashes=[6,2])
plt.show()
Which gives me the following result:
Which is correct given the code I am using. However, I would like to use a graph that keeps the variable value until the value changes, i.e. an horizontal line until the value changes, at which point the dots are connected by a vertical line. So instead of the above (for the blue), I'd have something like the black line shown here (I did only the start to illustrate it, forgive my terrible paint skills):
Any way of doing this? Thanks in advance.

This is what the drawstyle proptery is for. Use the 'steps-pre' style to achieve what you're looking for. See the drawstyle property section of matplotlib.lines.Line2D docs. (steps-pre and steps-post change whether the y-value is the beginning or end of the horizontal line; see Step Functions in Matplotlib for more examples and explanation.)
If you modify your code as follows, it should work as you want:
plt.plot(x, It)
plt.plot(x, NIt, dashes=[6,2], drawstyle='steps-pre')
plt.show()
Cheers!

Gnuplot: Plotting one series per line of input values

I have a CSV file that looks like this:
fft_0,fft_1,fft_2,fft_3,fft_4,fft_5,fft_6,fft_7,fft_8,fft_9,fft_10,fft_11,fft_12,fft_13,fft_14,fft_15,fft_16,fft_17,fft_18,fft_19,fft_20,fft_21,fft_22,fft_23,fft_24,fft_25,fft_26,fft_27,fft_28,fft_29,fft_30,fft_31,fft_32,fft_33,fft_34,fft_35,fft_36,fft_37,fft_38,fft_39,fft_40,fft_41,fft_42,fft_43,fft_44,fft_45,fft_46,fft_47,fft_48,fft_49,fft_50,fft_51,fft_52,fft_53,fft_54,fft_55,fft_56,fft_57,fft_58,fft_59,fft_60,fft_61,fft_62,fft_63,fft_64,fft_65,fft_66,fft_67,fft_68,fft_69,fft_70,fft_71,fft_72,fft_73,fft_74,fft_75,fft_76,fft_77,fft_78,fft_79,fft_80,fft_81,fft_82,fft_83,fft_84,fft_85,fft_86,fft_87,fft_88,fft_89,fft_90,fft_91,fft_92,fft_93,fft_94,fft_95,fft_96,fft_97,fft_98,fft_99,fft_100,fft_101,fft_102,fft_103,fft_104,fft_105,fft_106,fft_107,fft_108,fft_109,fft_110,fft_111,fft_112,fft_113,fft_114,fft_115,fft_116,fft_117,fft_118,fft_119,fft_120,fft_121,fft_122,fft_123,fft_124,fft_125,fft_126,fft_127,fft_128,fft_129,fft_130,fft_131,fft_132,fft_133,fft_134,fft_135,fft_136,fft_137,fft_138,fft_139,fft_140,fft_141,fft_142,fft_143,fft_144,fft_145,fft_146,fft_147,fft_148,fft_149,fft_150,fft_151,fft_152,fft_153,fft_154,fft_155,fft_156,fft_157,fft_158,fft_159,fft_160,fft_161,fft_162,fft_163,fft_164,fft_165,fft_166,fft_167,fft_168,fft_169,fft_170,fft_171,fft_172,fft_173,fft_174,fft_175,fft_176,fft_177,fft_178,fft_179,fft_180,fft_181,fft_182,fft_183,fft_184,fft_185,fft_186,fft_187,fft_188,fft_189,fft_190,fft_191,fft_192,fft_193,fft_194,fft_195,fft_196,fft_197,fft_198,fft_199,fft_200,fft_201,fft_202,fft_203,fft_204,fft_205,fft_206,fft_207,fft_208,fft_209,fft_210,fft_211,fft_212,fft_213,fft_214,fft_215,fft_216,fft_217,fft_218,fft_219,fft_220,fft_221,fft_222,fft_223,fft_224,fft_225,fft_226,fft_227,fft_228,fft_229,fft_230,fft_231,fft_232,fft_233,fft_234,fft_235,fft_236,fft_237,fft_238,fft_239,fft_240,fft_241,fft_242,fft_243,fft_244,fft_245,fft_246,fft_247,fft_248,fft_249,fft_250,fft_251,fft_252,fft_253,fft_254,fft_255
0.0,31.751653360516546,6.275520840013165,14.595752130320351,3.7868790683610323,23.453145120657318,17.968676508902426,13.077879510660095,5.524149879619814,9.159839191815607,3.4879570496415435,5.789890348672875,6.37158005487321,3.53593114100446,9.005729135469483,11.511943709884944,4.877113072123605,3.980766752139159,11.482684912439783,17.220737110365697,27.088212459502966,110.93476064590726,59.78887389689556,32.51075628874421,24.591418574709603,4.640853279203423,7.448545851889065,9.188366734225628,11.366826382304204,10.077018109797907,3.1841494684815577,5.190248731077729,3.4161263016208325,2.2026391207219995,14.97641334282317,5.673077411085896,12.884780698455764,6.998674823994672,7.342744118836382,3.949308507257039,4.395757811042787,16.103476980952966,28.2719870806011,10.88302198678709,2.685111390491833,10.686339936971915,6.408929713964431,12.069758412421345,15.72375095954655,4.119204604927627,14.874704697329062,11.498505785311869,11.117260027598117,9.494678844281257,5.266405910530414,10.915082550855102,8.417975130307454,18.801404884876543,29.51008177200432,10.843737620239258,20.365544144100863,49.61885082721084,24.743136974252824,95.12429979320565,216.99226248669268,49.341356893894115,18.766444144153137,51.565370474695136,43.7242611005549,54.48857810233984,43.66891218332103,26.853261639029913,6.866934892914652,11.299141562323118,5.318490604101198,31.524180684221047,21.059671101201328,11.17069564618422,17.446945303923478,15.79632859533589,25.8754797065767,25.202369290835293,40.374088558894044,26.000283711509223,55.62708932638661,66.77073066677998,71.71203146112138,48.980985792557924,14.286410652210266,4.601609981437789,15.070118260346232,23.802325341146616,8.327118721719636,11.442341360890286,22.05004217818876,11.104160787103668,12.484928716546818,9.739491305620902,5.5297569624177,7.37163250954064,35.75106868880271,7.399083813594336,26.329051989363144,16.913714138751928,22.74781071883487,20.59299921308038,41.09358072023589,81.47189388863296,61.740342954926696,12.309218911196457,10.244104070553457,4.305193519431507,4.316878112694274,15.939544124902632,12.56060454938032,6.747750800215833,10.325389983324909,14.998130859829269,28.18890104826635,11.0605430438416,8.185204031195694,26.87475337528722,12.662790798826446,41.035417238947375,65.0858268884065,65.54994660181138,21.677593542254662,149.35573051267886,212.42969462503808,74.30926892134302,24.507354570739256,40.76411049649439,35.10651624387605,36.09565222913914,23.539710351057625,25.542632631949893,4.102760694986416,11.980098370080432,13.609502549213738,21.93156128168799,10.081283648530139,15.769674404840714,5.192044221522882,11.771446279635393,12.094956753577113,9.917024863836527,1.2572695424313944,3.722053458526404,8.795658724551126,21.56071410293817,28.922799068534882,13.483122896667437,10.395965791400695,23.505506841117732,8.485560877844723,2.356254230310154,28.165902806102135,12.980298399346841,16.336712296798527,6.730154151533989,16.677864587364514,3.3409877465665216,7.077281578595023,6.446743875035899,19.33833179858605,11.2040774924139,23.43426023135171,21.06169641831372,8.485140511390588,9.068503134834177,3.670077295125947,19.14430606857007,32.42559040891663,28.48925355507031,7.279904785720349,25.259393926407167,20.742537308065206,24.09984129072362,11.414295313454046,3.6413514677095136,41.19050815699398,9.206157892358178,19.755370447153105,36.994783243438796,32.80074469851852,35.87411321258091,11.503107316858005,74.10255021280251,67.24504666591955,104.16768866937738,95.33294914217088,151.9884214593015,136.32292370844223,216.3859464252064,123.41220158493012,59.26669418804178,80.98912876710403,146.95475095348888,46.520877172048024,40.11129083574055,31.4062153719097,51.2525380944314,19.618477161063097,24.64912362290385,39.665889309349865,4.5420695812167695,12.352393331711527,12.913093028159468,5.7475173407962785,32.16753002725559,1.7358492153434433,8.723950884616885,12.467271027329899,14.083802770107315,17.92250369303905,7.86710602026345,7.794809991411701,13.58518272133987,6.524921604389587,15.979388080578659,16.559110564691427,20.67916970007909,18.224245061592946,7.096787929904062,8.373793561958955,6.55812817381509,13.905987460060079,20.595153639426073,8.807333502576107,13.82796348336836,2.18887726814401,6.318371489436107,2.993337999476443,18.749653399598177,6.345591182705673,9.761309360285061,30.96989586919761,8.11119534172852,10.866890070470923,11.517755176146323,27.4609347160214,16.135144173727756,10.6448246437425,4.154792885980834,17.62396431228251,9.509942088880527,15.555429074090473,15.031228264687387,0.9801466560635561,0.7645844300931341,14.154728612808947,12.552555345029779,32.44796170517449,19.530604457901777,11.95976683879656,46.42256522056603
0.0,19.16432992306051,19.616997783340636,24.44119947886979,4.201389789467854,21.74285992321492,21.832776487663676,5.487401249578947,11.746651370331632,1.9601369533755433,5.622561176369094,4.96631977374031,10.097588355385781,5.08483320481312,9.445414620036079,14.222808225039186,2.696213466317052,7.638899760644791,15.041153329998348,10.391749304040763,32.3476575096254,108.99204640400545,63.57497610505674,22.696101813324205,7.872359102700095,21.52130460513689,10.111810799980553,12.724059804396923,19.009158214375578,12.65449693937476,9.132000916109536,6.326763343031359,4.879855924465264,3.871345327977384,10.924451311265537,7.589696386926958,8.18649996093532,11.551503954959513,11.064148190492709,6.176531003718973,15.62762103722472,11.29474719219796,15.477100373471712,34.31169456951676,4.869630599520906,15.140471298507281,8.259616875565543,7.215380685669043,10.46794882830988,19.43560849652611,4.529173954916338,4.35512822937366,2.895187451236368,12.790221568530207,15.09029777868783,17.31295887292244,6.845725037238285,11.696984535700611,29.19412768846885,10.816150558470914,17.795519392349565,18.95627545053494,19.39179148839016,51.25978750420467,258.9220546686427,26.60895810146767,60.12526975188942,57.965437788392094,56.17033578719,61.73076599694442,42.65192391821165,11.56253870818451,25.30486166396842,14.689367444907104,17.68946470063505,12.000531269987114,22.046788191423992,10.461190794614817,15.381278597253058,20.56941785579303,11.378832916602038,17.079026604217585,27.64811379662995,15.945260538344455,17.85973583587812,91.07244530248128,38.79336310420707,9.977752149534174,4.141735910598209,12.882679361205826,7.206277012438345,10.771526867887964,5.877615826490578,12.242065277916515,13.334594521312354,4.29007685290975,7.68709934271143,18.61924420361514,8.74553477917526,8.73628302646769,20.257192090857302,28.872335112983553,4.536051852152141,30.617387864205337,17.858689013107693,41.73630055399866,58.39281594824643,87.24012438534487,31.066544056426327,41.13149447740131,32.42269508871998,26.269987698517536,11.740763622173773,11.004766324349793,18.09863936075447,9.819248943124844,12.893499378743552,10.563553823125307,39.29361373727987,12.346894479852338,8.459770692508902,57.310236078713004,33.1311985608261,28.907897941787073,70.32655132146188,84.24779353195314,61.25485848237276,84.84845471667461,288.2138613792481,109.16667530743895,77.57183940606394,87.3425139617006,68.57701371566155,45.68772118776169,50.0797905239745,33.09749205216209,18.007490834401867,16.334260550527407,31.433003074249346,9.246945751725423,7.074363738698788,4.307268210922044,19.74271610979451,12.91162042059288,21.84937055988338,32.36398718338645,7.281588590668135,10.08373606540601,24.552336456417798,14.7860174786099,21.65070646215015,7.715805417675984,10.173892601354071,10.838760273837256,29.862805175973264,20.040881398274966,26.198025016148872,7.413741554718165,17.48934776894029,6.937450524150569,12.17991859460801,11.285099309978527,16.819830852613755,8.77192614757165,12.64143434466125,25.385516815011027,7.3675506195003875,12.129509801209169,28.94513170225861,20.395460170229377,22.488513131279987,21.01810252560465,35.136025982361815,10.139560341414699,3.555043053681657,31.343112942532223,14.592550641227064,17.64468740002523,26.880409076658076,22.11422795022885,27.4977856180402,30.104920205536807,39.53169334361884,11.71294285354865,23.425805677846594,67.79219601206428,42.27107919700437,64.88620076244453,117.15891789296428,99.78292099303975,48.71538731259637,90.15956877488314,95.77784729934608,101.95350156422501,96.21863000138868,142.43852409191666,151.1858655495999,120.64765073899484,79.83194264924788,65.59195836122893,31.013619590967267,23.420785189214566,28.712244731781265,24.5375312236021,37.231275049400224,22.30698063637999,3.466152702405225,21.930586433683153,12.983286870554023,33.3275146767313,16.019629125908292,13.374161083992483,14.140770556831407,22.17215831856053,11.313270491326389,15.68024673516814,12.986483554144087,23.331903515521233,3.864860667678062,13.76293655930224,29.7546331148781,10.197145120256085,9.949295198338554,23.03483024580453,7.954340759704595,5.206921160805673,12.442782717659927,15.289085530882318,5.497348053429443,6.255156597717796,8.342835500469203,14.66372085309629,16.322270250668957,8.194736256097809,24.397351809392624,17.884522130787275,7.68573327606993,8.180457570504249,33.303256527001146,5.769925562021384,15.466629545524382,12.651255525791012,15.995160619641469,12.922309957994937,6.556673050829525,6.941908198528731,4.617550389093913,27.335731696306702,5.814856112558841,18.49864018853029,13.96291681057734,35.903064134866256,38.73619761839379,32.56594885594187,54.105909842976,30.470991913000084
[...]
I want to be able to plot a new series per line (legend not necessary). The x-values should just start at 0 and increment from there, the y-values are given by the numbers in the file. The result should be something like this:
This was made in Excel, and if it weren't so labourous, this would be fine.
Note that answers using python/matplotlib are also welcomed.
Thanks a lot!
EDIT: This is as far as I've come, based on the answer provided in gnuplot: How to plot each line of a data file as Y and incremental X and other places. So far, there's for some reason no output file written, although it's definitely doing something (because the last command takes a few seconds to finish).
set term png
set output "fft.png"
set datafile sep ','
plot for [i=1:255] 'fft.csv' using (i):(column(i)) with lines
EDIT 2: I now have this, which is closer, but still not what I want. Each line in the input file should be a series. It seems now each column is a series.
set term png
set output "fft.png"
set datafile sep ','
unset key
plot for [i=1:255] 'fft.csv' using (i):(column(i)) with lines

Right, I think I solved it (using the answer from https://stackoverflow.com/a/8716495/666259 and the answer from Christoph):
set terminal png size 1920,1080
set datafile sep ","
unset key
set xtics 0,5,255
set title "mytitle"
set autoscale cbfix
plot "fft.csv" matrix using 1:3:2 with lines palette
This gives me something like this:

In order to have every line with a different color, use either palette or linecolor variable:
set datafile separator ','
set autoscale cbfix
plot 'file.csv' matrix every :::1 using 1:3:2 with lines palette
This uses the row number to color the lines based on the current palette. This is very useful if you have many lines to draw. set autoscale cbfix prevents the color range to be extended to the next major tics.
For only a few lines, you could also use
plot 'file.csv' matrix every :::1 using 1:3:2 linecolor variable with lines
This uses the row number as index for the linetype.

Matplotlib adding overlay labels to an axis

In matplotlib I wish to know the cleanest and most robust means of overlaying labels onto an axis. This is probably best demonstrated with an example:
While normal axis labels/ticks are placed every 5.00 units additional labels without ticks have been overlayed onto the axis (this can be seen at 1113.75 which partially covers 1114.00 and 1105.00 which is covered entirely). The labels also have the same font and size as their normal, ticked, counterparts with the background (if any) going right up to the axis (as a tick mark would).
What is the simplest way of obtaining this effect in matplotlib?
Edit
Following on from #Ken's suggestion I have managed to obtain the effect for an existing tick/label by using ax.yaxis.get_ticklines and ax.yaxis.get_ticklabels to both remove the tick marker and change the background/font/zorder of a label. However, I am unsure how best to add a new tick/label to an axis.
In other words I am looking for a function add_tick(ax.yaxis, loc) that adds a tick at location loc and returns the tickline and ticklabel objects for me to operate on.

I haven't ever tried to do that, but I think that the Artist tutorial might be helpful for you. In particular, the last section has the following code:
for line in ax1.yaxis.get_ticklines():
# line is a Line2D instance
line.set_color('green')
line.set_markersize(25)
line.set_markeredgewidth(3)
I think that using something like line.set_markersize(0) might make the markers have size zero. The difficult part might be finding the ones that need that done. It is possible that the line.xdata or line.ydata arrays might contain enough information to isolate the ones you need. Of course, if you are manually adding the tick marks, it is possible that as you do that the instance gets returned, so you can just modify them as you create them.

The best solution I have been able to devise:
# main: axis; olocs: locations list; ocols: location colours
def overlay_labels(main, olocs, ocols):
# Append the overlay labels as ticks
main.yaxis.set_ticks(np.append(main.yaxis.get_ticklocs(), olocs))
# Perform generic formatting to /all/ ticks
# [...]
labels = reversed(main.yaxis.get_ticklabels())
markers = reversed(main.yaxis.get_ticklines()[1::2]) # RHS ticks only
glines = reversed(main.yaxis.get_gridlines())
rocols = reversed(ocols)
# Suitably format each overlay tick (colours and lines)
for label,marker,grid,colour in izip(labels, markers, glines, rocols):
label.set_color('white')
label.set_backgroundcolor(colour)
marker.set_visible(False)
grid.set_visible(False)
It is not particularly elegant but does appear to work.

How to plot a multicolored curve using a single plot command in matplotlib

If I understand correctly, the function:
matplotlib.pyplot.plot(x, y)
plots len(x)-1 separate line segments - one going from (x[0], y[0]) to (x[1],y[1]), one going from (x[1],y[1]) to (x[2], y[2]), etc. In my application, I want to display a curve consisting of a series of line segments connecting data points in this way, but there is an extra piece of data (z) associated with the transition between each of these data points, that I want to represent by the color of the line segment. Clearly one way of doing this is the following:
for i in range(len(x)-1)):
matplotlib.pyplot.plot(x[i:i+2],y[i:i+2], color=z[i])
but is there a way to do it that doesn't involve a separate call to matplotlib.pyplot.plot for each line segment?

You should be able to use matplotlib.collections.LineCollection which accepts a colors parameter (sequence of RGBA tuples).

If you implement a colorbar, something similar to this, then you should be able to do it in one line. The trick may be to pick a colorscale that changes on the order of your line segments.