当我们用matplotlib作图时中文乱码，往往会发现中文的文字变成了小方块，我在绘制决策树的时候就碰到了这个问题。将各种方式试了个遍，都不管用……最终发现是没有删除matplotlib下字体的缓存目录，即~/.cache/matplotlib
下面记录找到的比较好的方法，以便下次使用。
1、环境查看
a.系统版本查看
linuxidc@linuxidc:~/www.linuxidc.com$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=18.04
DISTRIB_CODENAME=bionic
DISTRIB_DESCRIPTION="Ubuntu 18.04.2 LTS"
b.系统中文字体查看
linuxidc@linuxidc:~/www.linuxidc.com$ fc-list :lang=zh
/usr/share/fonts/truetype/arphic/uming.ttc: AR PL UMing TW MBE:style=Light
/home/linuxidc/.local/share/fonts/方正准圆简体.TTF: 方正准圆简体,FZZhunYuan\-M02S:style=Regular
/usr/share/fonts/opentype/noto/NotoSansCJK-Bold.ttc: Noto Sans CJK JP,Noto Sans CJK JP Bold:style=Bold,Regular
/usr/share/fonts/opentype/noto/NotoSerifCJK-Bold.ttc: Noto Serif CJK SC:style=Bold
/usr/share/fonts/opentype/noto/NotoSerifCJK-Bold.ttc: Noto Serif CJK TC:style=Bold
/usr/share/fonts/truetype/arphic/ukai.ttc: AR PL UKai CN:style=Book
/usr/share/fonts/truetype/arphic/ukai.ttc: AR PL UKai HK:style=Book
/usr/share/fonts/opentype/noto/NotoSerifCJK-Bold.ttc: Noto Serif CJK JP:style=Bold
/usr/share/fonts/opentype/noto/NotoSerifCJK-Bold.ttc: Noto Serif CJK KR:style=Bold
/usr/share/fonts/truetype/arphic/ukai.ttc: AR PL UKai TW:style=Book
/usr/share/fonts/opentype/noto/NotoSansCJK-Bold.ttc: Noto Sans Mono CJK KR,Noto Sans Mono CJK KR Bold:style=Bold,Regular
/usr/share/fonts/opentype/noto/NotoSansCJK-Bold.ttc: Noto Sans Mono CJK JP,Noto Sans Mono CJK JP Bold:style=Bold,Regular
/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc: Noto Sans CJK JP,Noto Sans CJK JP Regular:style=Regular
/usr/share/fonts/opentype/noto/NotoSansCJK-Bold.ttc: Noto Sans Mono CJK TC,Noto Sans Mono CJK TC Bold:style=Bold,Regular
/usr/share/fonts/opentype/noto/NotoSerifCJK-Regular.ttc: Noto Serif CJK SC:style=Regular
/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc: Noto Sans CJK KR,Noto Sans CJK KR Regular:style=Regular
/usr/share/fonts/opentype/noto/NotoSerifCJK-Regular.ttc: Noto Serif CJK TC:style=Regular
/usr/share/fonts/opentype/noto/NotoSerifCJK-Regular.ttc: Noto Serif CJK JP:style=Regular
/usr/share/fonts/opentype/noto/NotoSerifCJK-Regular.ttc: Noto Serif CJK KR:style=Regular
/usr/share/fonts/opentype/noto/NotoSansCJK-Bold.ttc: Noto Sans Mono CJK SC,Noto Sans Mono CJK SC Bold:style=Bold,Regular
/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc: Noto Sans Mono CJK JP,Noto Sans Mono CJK JP Regular:style=Regular
/usr/share/fonts/truetype/droid/DroidSansFallbackFull.ttf: Droid Sans Fallback:style=Regular
/usr/share/fonts/opentype/noto/NotoSansCJK-Bold.ttc: Noto Sans CJK TC,Noto Sans CJK TC Bold:style=Bold,Regular
/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc: Noto Sans Mono CJK KR,Noto Sans Mono CJK KR Regular:style=Regular
/usr/share/fonts/opentype/noto/NotoSansCJK-Bold.ttc: Noto Sans CJK SC,Noto Sans CJK SC Bold:style=Bold,Regular
/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc: Noto Sans CJK SC,Noto Sans CJK SC Regular:style=Regular
/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc: Noto Sans CJK TC,Noto Sans CJK TC Regular:style=Regular
/usr/share/fonts/truetype/arphic/ukai.ttc: AR PL UKai TW MBE:style=Book
/home/linuxidc/.local/share/fonts/SIMHEI.TTF: 黑体,SimHei:style=Regular,Normal,obyčejné,Standard,Κανονικά,Normaali,Normál,Normale,Standaard,Normalny,Обычный,Normálne,Navadno,Arrunta
/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc: Noto Sans Mono CJK TC,Noto Sans Mono CJK TC Regular:style=Regular
/usr/share/fonts/truetype/arphic/uming.ttc: AR PL UMing TW:style=Light
/usr/share/fonts/truetype/arphic/uming.ttc: AR PL UMing CN:style=Light
/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc: Noto Sans Mono CJK SC,Noto Sans Mono CJK SC Regular:style=Regular
/usr/share/fonts/truetype/arphic/uming.ttc: AR PL UMing HK:style=Light
/home/linuxidc/.local/share/fonts/文泉驿正黑.ttf: 文泉驿正黑,文泉驛正黑,WenQuanYi Zen Hei:style=Medium,中等
/home/linuxidc/.local/share/fonts/方正水柱_GBK.ttf: 方正水柱_GBK,FZShuiZhu\-M08:style=Regular
/usr/share/fonts/opentype/noto/NotoSansCJK-Bold.ttc: Noto Sans CJK KR,Noto Sans CJK KR Bold:style=Bold,Regular
c.Python版本及matplotlib配置文件位置查询