GPS数据Python解析及地图可视化
本篇文章主要介绍如何使用pynmea2库解析传感器的GPS信号，以及如何使用folium库绘制GPS轨迹图。
GPS数据解析
根据NMEA协议，我们从传感器上接收到的GPS经纬度数据格式如下：
例：$GPRMC,024813.640,A,3158.4608,N,11848.3737,E,10.05,324.27,150706,,,A*50
字段0：$GPRMC，语句ID，表明该语句为Recommended Minimum Specific GPS/TRANSIT Data（RMC）推荐最小定位信息
字段1：UTC时间，hhmmss.sss格式
字段2：状态，A=定位，V=未定位
字段3：纬度ddmm.mmmm，度分格式（前导位数不足则补0）
字段4：纬度N（北纬）或S（南纬）
字段5：经度dddmm.mmmm，度分格式（前导位数不足则补0）
字段6：经度E（东经）或W（西经）
字段7：速度，节，Knots
字段8：方位角，度
字段9：UTC日期，DDMMYY格式
字段10：磁偏角，（000 - 180）度（前导位数不足则补0）
字段11：磁偏角方向，E=东W=西
字段12：模式，A=自动，D=差分，E=估测，N=数据无效（3.0协议内容）
字段13：校验值（$与*之间的数异或后的值）
这里以GPRMC为例，GPGGA同理。
根据协议内容，我们可以自己编写Python脚本对GPS数据进行解析。但是，实际上Python已经有现成的库可以调用——pymea2。
推荐下载方式：
pip install pynmea2
下载完成后即可导入包，并通过pynmea2.parse()方法对GPS数据进行解析，示例如下：
import pynmea2
text = "$GNRMC,074733.00,A,2241.28818,N,11358.44210,E,3.866,,070720,,,A*60"
msg = pynmea2.parse(text)
解析结果如下：
原始GPS信号的经纬度采用的是60进制的格式，通过msg.lat和msg.lon就能分别显示维度和经度信息：
而地图常用的格式应该是10进制的，通过msg.latitude和msg.longitude就能分别显示10进制的维度和经度信息：
使用folium绘制经纬度轨迹图
通过上面的解析方法，我们已经获取了传感器的维度和经度信息，接下来就能够在地图上进行可视化展示，这里我采用的是Python的folium库。
假设我们最终获取到的一批经纬度数据如下：
locations = [[22.674574, 113.993353], [22.674544, 113.993362], [22.674521, 113.993376], [22.67447, 113.99342], [22.674471, 113.993428], [22.674485, 113.993434], [22.674487, 113.993437], [22.674471, 113.993416], [22.674452, 113.993416], [22.674449, 113.993412], [22.674443, 113.993389], [22.674444, 113.993382], [22.67445, 113.993363], [22.67444, 113.993358], [22.67444, 113.993351], [22.67444, 113.993338], [22.674441, 113.993331], [22.674485, 113.993265], [22.674452, 113.993305], [22.674511, 113.99323], [22.674504, 113.993236], [22.674484, 113.99326], [22.674419, 113.993359], [22.67441, 113.993369], [22.674403, 113.993381], [22.674406, 113.993385], [22.674406, 113.993395], [22.674404, 113.993397], [22.674403, 113.9934], [22.674402, 113.993411], [22.6744, 113.993414], [22.674398, 113.993417], [22.674308, 113.993457], [22.674269, 113.99347], [22.67423, 113.99349], [22.674191, 113.993506], [22.674151, 113.993532], [22.674045, 113.993583], [22.673965, 113.993597], [22.673879, 113.993607], [22.673724, 113.993639], [22.673321, 113.993752], [22.673212, 113.993784], [22.673101, 113.993825], [22.672887, 113.993894], [22.672785, 113.993937], [22.672684, 113.993977], [22.672476, 113.994081], [22.672063, 113.994352], [22.671971, 113.994427], [22.671873, 113.994503], [22.67178, 113.994583], [22.671449, 113.994935], [22.671373, 113.995017], [22.671315, 113.995096], [22.671252, 113.995173], [22.671199, 113.995219], [22.671165, 113.99525], [22.671108, 113.995304], [22.671128, 113.995301], [22.671125, 113.995312], [22.671131, 113.995302], [22.671133, 113.995301], [22.671136, 113.99531], [22.671135, 113.995313], [22.671131, 113.995316], [22.671077, 113.995376], [22.671059, 113.995395], [22.671039, 113.995415], [22.670993, 113.995452], [22.670868, 113.995574], [22.670666, 113.995825], [22.67061, 113.995877], [22.670563, 113.995943], [22.670503, 113.996008], [22.670448, 113.996076], [22.670393, 113.996143], [22.670233, 113.996335], [22.670022, 113.996558], [22.669967, 113.996622], [22.669913, 113.996683], [22.669862, 113.996741], [22.669812, 113.996795], [22.669768, 113.996847], [22.669734, 113.996899], [22.669687, 113.996965], [22.669639, 113.997026], [22.669441, 113.997291], [22.669385, 113.997353], [22.669331, 113.997423], [22.669274, 113.997491], [22.669216, 113.997564], [22.66915, 113.997639], [22.668873, 113.997982], [22.668809, 113.998056], [22.668754, 113.998126], [22.668686, 113.998199], [22.668632, 113.998269], [22.668578, 113.998336], [22.66852, 113.998408], [22.668462, 113.998486], [22.668212, 113.998776], [22.668152, 113.998849], [22.668082, 113.998925], [22.667963, 113.999024], [22.667923000000002, 113.999077], [22.667784, 113.999228], [22.667669, 113.999349], [22.667521, 113.999529], [22.667482, 113.999574], [22.667442, 113.999625], [22.667401, 113.999676], [22.667358, 113.999724], [22.667321, 113.999774], [22.667283, 113.99982], [22.667246, 113.999863], [22.667209, 113.999906], [22.667169, 113.999947], [22.667128, 113.999992], [22.667085, 114.000046], [22.667043, 114.000096], [22.667, 114.000147], [22.666961, 114.000199], [22.66692, 114.000247], [22.66688, 114.000286], [22.666841, 114.000334], [22.666797, 114.000384], [22.66673, 114.000437], [22.666673, 114.000496], [22.666607, 114.000549], [22.666545, 114.000612], [22.666287, 114.000833], [22.66621, 114.000882], [22.666138, 114.000926], [22.66606, 114.00099], [22.665972, 114.001058], [22.665891, 114.001114], [22.665809, 114.001158], [22.665725, 114.001216], [22.665635, 114.001275], [22.665255, 114.001479], [22.665149, 114.001524], [22.66504, 114.001577], [22.664923, 114.001628], [22.664575, 114.001775], [22.664114, 114.001933], [22.664001, 114.001966], [22.663888, 114.00199], [22.663774, 114.002035], [22.663655, 114.002067], [22.66353, 114.002101], [22.663402, 114.002132], [22.663275, 114.002169], [22.663148, 114.002203], [22.66266, 114.002342], [22.662544, 114.002373], [22.662429, 114.0024], [22.662106, 114.002517], [22.662032, 114.00255], [22.661957, 114.002583], [22.661886, 114.002604], [22.661814, 114.002636], [22.661663, 114.0027], [22.661583, 114.00274], [22.661315, 114.002878], [22.661247, 114.002907], [22.661185, 114.002932], [22.66113, 114.00296], [22.660899, 114.003051], [22.660847, 114.003065], [22.660659, 114.003121], [22.660608, 114.003139], [22.66058, 114.003162], [22.660565, 114.003191], [22.660538, 114.003213], [22.660508, 114.003231], [22.660495, 114.003259], [22.660458, 114.003296], [22.660429, 114.003397], [22.660408, 114.003464], [22.660378, 114.00354], [22.660363, 114.003564], [22.660314, 114.003608], [22.6602, 114.003818], [22.660175, 114.003876], [22.660049, 114.004195], [22.660021, 114.004256], [22.66, 114.004318], [22.659912, 114.004546], [22.659893, 114.004602], [22.659884, 114.004656], [22.659863, 114.004709], [22.65984, 114.004772], [22.659823, 114.004833], [22.659774, 114.004916], [22.659742, 114.004953], [22.659702, 114.004991], [22.659526, 114.00511], [22.659313, 114.005117], [22.659275, 114.005128], [22.659236, 114.005143], [22.659204, 114.005154], [22.659177, 114.005174], [22.659, 114.005249], [22.658954, 114.005246], [22.65891, 114.005242], [22.658881, 114.005232], [22.658862, 114.005226], [22.658822, 114.005206], [22.658791, 114.005192], [22.658759, 114.005171], [22.658612, 114.005036], [22.658563, 114.005019], [22.658514, 114.005001], [22.65846, 114.004978], [22.65841, 114.004958], [22.658359, 114.004939], [22.658102, 114.0049], [22.658043, 114.004901], [22.6577, 114.00493], [22.657606, 114.004941], [22.657507, 114.004945], [22.657422, 114.004959], [22.657338, 114.00497], [22.657009, 114.005009], [22.656778, 114.005121], [22.656726, 114.005149], [22.656679, 114.005174], [22.656635, 114.005197], [22.656598, 114.005217], [22.656512, 114.00526], [22.656477, 114.005279], [22.656426, 114.005314], [22.656315, 114.005396], [22.656256, 114.00544], [22.656188, 114.00549], [22.65605, 114.005583], [22.655815, 114.005766], [22.655529, 114.005985], [22.655465, 114.006031], [22.655409, 114.006071], [22.655205, 114.00624], [22.65511, 114.006312], [22.655066, 114.006345], [22.654989, 114.006407], [22.65491, 114.006467], [22.654868, 114.006496], [22.654832, 114.006524], [22.654792, 114.006552], [22.654674, 114.006626], [22.654656, 114.006641], [22.654631, 114.006665], [22.654624, 114.006669], [22.654613, 114.006677], [22.654597, 114.006687], [22.65459, 114.006694], [22.654584, 114.006698], [22.654579, 114.006702], [22.654573, 114.006706], [22.654555, 114.006716], [22.654554, 114.006715], [22.654555, 114.006715], [22.654555, 114.006715], [22.654555, 114.006717], [22.654555, 114.006719], [22.654539, 114.00674], [22.654529, 114.006756], [22.654509, 114.00678], [22.654481, 114.006809], [22.654417, 114.006871], [22.654407, 114.006882], [22.654394, 114.006892], [22.654363, 114.006916], [22.65432, 114.006949], [22.654302, 114.006962], [22.654289, 114.006973], [22.654275, 114.006982], [22.654257, 114.006994], [22.65424, 114.007007], [22.654223, 114.007018], [22.654195, 114.007035], [22.654146, 114.007078], [22.65413, 114.007096], [22.654124, 114.007102], [22.654116, 114.00711], [22.654035, 114.00718], [22.653994, 114.007212], [22.653942, 114.007248], [22.653891, 114.007284], [22.653837, 114.007319], [22.653782, 114.00736], [22.653725, 114.007406], [22.653665, 114.007455], [22.653604, 114.007507], [22.653537, 114.007559], [22.653237, 114.007795], [22.653162000000002, 114.007853], [22.652859, 114.008086], [22.65279, 114.008141], [22.652722, 114.008193], [22.652486, 114.008392], [22.652425, 114.008436], [22.652364, 114.008478], [22.652141, 114.008652], [22.651907, 114.008831], [22.651843, 114.008877], [22.651779, 114.008923], [22.651713, 114.008971], [22.651653, 114.009008], [22.651391, 114.009213], [22.651153, 114.009397], [22.651097, 114.00944], [22.651041, 114.009481], [22.650994, 114.009514], [22.650954, 114.009544], [22.650919000000002, 114.009572], [22.650851, 114.009628], [22.650815, 114.009661], [22.65078, 114.00969], [22.650748, 114.009719], [22.650626, 114.009822], [22.65059, 114.009849], [22.65056, 114.009878], [22.65052, 114.009909], [22.6504, 114.010005], [22.650277, 114.010077], [22.650266, 114.01009], [22.65026, 114.010104], [22.65026, 114.010105], [22.650258, 114.010107], [22.650254, 114.01011], [22.650244, 114.010115], [22.65025, 114.010123], [22.65025, 114.010126], [22.650253, 114.010131], [22.650257, 114.010133], [22.650256, 114.010134], [22.650252000000002, 114.010136], [22.65025, 114.010136], [22.650243, 114.010136], [22.650249, 114.010139], [22.650238, 114.010139], [22.650215, 114.010136], [22.650215, 114.010139], [22.650212, 114.010143], [22.650206, 114.010148], [22.650205, 114.010155], [22.6502, 114.010159], [22.650197, 114.010161], [22.650194, 114.010163], [22.650187, 114.010171], [22.650187, 114.010172], [22.650187, 114.010174], [22.650187, 114.010176], [22.650187, 114.010178], [22.650186, 114.010178], [22.650176, 114.010181], [22.65017, 114.010186], [22.650168999999998, 114.010187], [22.65017, 114.010188], [22.65017, 114.010189], [22.650174, 114.01019], [22.650174, 114.01019], [22.650175, 114.010185], [22.650177, 114.010184], [22.65018, 114.010183], [22.650181, 114.010184], [22.650179, 114.010183], [22.650175, 114.010181], [22.650164, 114.010177], [22.650164, 114.010168], [22.65016, 114.010171], [22.650156, 114.010171], [22.650077, 114.010223], [22.65005, 114.010245], [22.650019, 114.010266], [22.64999, 114.01029], [22.64996, 114.010309], [22.649917, 114.010341], [22.649892, 114.010353], [22.649874, 114.010367], [22.649844, 114.01039], [22.649637, 114.010561], [22.649569, 114.010614], [22.649493, 114.010679], [22.649349, 114.010807], [22.64928, 114.010869], [22.649211, 114.010927], [22.649142, 114.010986], [22.649075, 114.011046], [22.64888, 114.01122], [22.648835, 114.011255], [22.648791, 114.01129], [22.648697, 114.011371], [22.648469, 114.011552], [22.64841, 114.011602], [22.648349, 114.011651], [22.648288, 114.011697], [22.648226, 114.011744], [22.648162, 114.01179], [22.647882, 114.012002], [22.647812000000002, 114.012056], [22.647737, 114.012115], [22.647455, 114.01231], [22.647386, 114.01235], [22.647316, 114.01239], [22.647259, 114.01242], [22.647165, 114.012422], [22.647145, 114.012414], [22.647127, 114.012402], [22.647107, 114.012387], [22.647089, 114.012372], [22.647061, 114.012348], [22.647032, 114.012301], [22.646994, 114.012256], [22.646963, 114.012211], [22.646934, 114.012167], [22.6469, 114.012126], [22.646858, 114.012074], [22.646829, 114.012025], [22.646798, 114.011976], [22.646676, 114.011792], [22.646641, 114.011738], [22.646593, 114.011682], [22.646548, 114.011619], [22.646392, 114.011391], [22.646359, 114.011348], [22.646242, 114.011275], [22.64621, 114.011284], [22.646176, 114.011308], [22.646057, 114.011403], [22.646036, 114.011422], [22.646023, 114.011419], [22.645966, 114.011418], [22.645968, 114.01141], [22.645971, 114.011398], [22.645968, 114.011385], [22.645959, 114.011384], [22.645965, 114.011382], [22.645963, 114.011381], [22.645963, 114.011377], [22.645955, 114.011391], [22.64595, 114.011385], [22.645947, 114.011383], [22.64595, 114.011378], [22.645932, 114.011349], [22.645955999999998, 114.011367], [22.645954, 114.011364], [22.64595, 114.011361], [22.645944, 114.011363], [22.645945, 114.011366], [22.645925, 114.011378], [22.645917, 114.011377], [22.645914, 114.01137], [22.645915, 114.011394], [22.645914, 114.011395], [22.645919, 114.011399], [22.645902, 114.011416], [22.645927, 114.01145], [22.645934, 114.01145], [22.645931, 114.011415], [22.645931, 114.011423], [22.64594, 114.011465], [22.645958, 114.011438], [22.64597, 114.011438], [22.645948, 114.011414], [22.645972, 114.011407], [22.645969, 114.011389], [22.645957, 114.011383], [22.645966, 114.011391], [22.646028, 114.011349], [22.646038, 114.011348], [22.646038, 114.011346], [22.646144, 114.011338], [22.646165, 114.011331], [22.646185, 114.011323], [22.646296, 114.011279], [22.646366, 114.011254], [22.646385, 114.011245], [22.646409, 114.011188], [22.64643, 114.011175], [22.645819, 114.011172], [22.645744, 114.011106], [22.645695, 114.011069], [22.64569, 114.011058], [22.64581, 114.011152], [22.645709, 114.011067], [22.645675, 114.011042], [22.645633, 114.011031], [22.645633, 114.011066], [22.645639, 114.011083], [22.645645000000002, 114.01109], [22.64563, 114.011079], [22.645635, 114.011107], [22.645651, 114.011131], [22.645679, 114.011169], [22.645688, 114.011188], [22.645694, 114.011194], [22.645697, 114.011206], [22.6457, 114.011215], [22.645707, 114.011226], [22.645692, 114.011203], [22.645708, 114.011211], [22.645718, 114.011244], [22.645722, 114.011281]]
注意：顺序为[纬度，经度]。
编写Python函数绘制GPS轨迹图：
def draw_gps(locations, output_path, file_name):
"""
绘制gps轨迹图
:param locations: list, 需要绘制轨迹的经纬度信息，格式为[[lat1, lon1], [lat2, lon2], ...]
:param output_path: str, 轨迹图保存路径
:param file_name: str, 轨迹图保存文件名
:return: None
"""
m = folium.Map(locations[0], zoom_start=15, attr='default') #中心区域的确定
folium.PolyLine( # polyline方法为将坐标用线段形式连接起来
locations, # 将坐标点连接起来
weight=3, # 线的大小为3
color='orange', # 线的颜色为橙色
opacity=0.8 # 线的透明度
).add_to(m) # 将这条线添加到刚才的区域m内
# 起始点，结束点
folium.Marker(locations[0], popup='<b>Starting Point</b>').add_to(m)
folium.Marker(locations[-1], popup='<b>End Point</b>').add_to(m)
m.save(os.path.join(output_path, file_name)) # 将结果以HTML形式保存到指定路径
GPS轨迹图结果：
解决folium国内访问太慢的问题
如果我们直接用浏览器打开生成的HTML文件，有可能会发现网络访问非常缓慢，需要加载大概1分钟才能看到地图显现。
我们打开用folium生成的HTML文件就可以看到：
由于生成的HTML文件调用的很多资源都是访问的国外资源，所以在国内打开可能会比较慢。这时候我们可以考虑把这些静态资源下载到本地，然后采用Python读取HTML，修改静态资源路径的方式，把HTML中的css和js路径修改成本地路径，这样就能够极大程度的提高速度。
示例如下：
可以看到示例中有一行我没有进行修改，这是因为我在前面绘制地图的时候增加了起始点的绘制，如果把这个css路径改了就会导致无法正常显示起始点（没有下载起始点图标），再加上这个css网络访问起来并不慢，所以我没有进行替换。
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/leaflet@1.6.0/dist/leaflet.css"/>
修改了静态资源访问路径的HTML，再次打开的速度应该是非常快的，如果地图加载依然比较慢，那就是地图瓦片的网络问题了，而非静态资源的问题。
切换为高德底图
如果觉得folium默认使用的底图太丑，也可以将其修改为国内的高德底图，这样不仅更好看，而且底图的加载速度也会更快。
把前面的绘制GPS轨迹代码修改如下：
def draw_gps(locations, output_path, file_name):
"""
绘制gps轨迹图
:param locations: list, 需要绘制轨迹的经纬度信息，格式为[[lat1, lon1], [lat2, lon2], ...]
:param output_path: str, 轨迹图保存路径
:param file_name: str, 轨迹图保存文件名
:return: None
"""
m = folium.Map(locations[0], # 中心区域的确定
zoom_start=15,
tiles="http://webrd02.is.autonavi.com/appmaptile?lang=zh_cn&size=1&scale=1&style=7&x={x}&y={y}&z={z}", # 设置高德底图
attr='default')
folium.PolyLine( # polyline方法为将坐标用线段形式连接起来
locations, # 将坐标点连接起来
weight=3, # 线的大小为3
color='orange', # 线的颜色为橙色
opacity=0.8 # 线的透明度
).add_to(m) # 将这条线添加到刚才的区域m内
# 起始点，结束点
folium.Marker(locations[0], popup='<b>Starting Point</b>').add_to(m)
folium.Marker(locations[-1], popup='<b>End Point</b>').add_to(m)
m.save(os.path.join(output_path, file_name)) # 将结果以HTML形式保存到指定路径
其实就是设置了folium.Map()方法的tiles参数而已。
采用高德底图的GPS轨迹结果如下：
更多的底图可以参考：高德WMTS规则
有人可能会发现，绘制出来的轨迹图和前面的不一样，而且明显轨迹都不在路上。这是因为采用不同的底图需要进行相应的纠偏操作，也就是需要把gps坐标转换为高德坐标，否则就会发生这样的情况。
具体的纠偏操作可以参考：其他坐标转高德坐标的JS API。
因为高德开放平台只提供了JS API，没有提供Python API，所以本篇文章不作详细介绍，如果感兴趣的朋友可以自行了解。
